With the development of functional integration and compactness design for next generation aeroengine,the ineffective dissipation and utilization of excess heat is one of the key research topics.This paper develops a n...With the development of functional integration and compactness design for next generation aeroengine,the ineffective dissipation and utilization of excess heat is one of the key research topics.This paper develops a novel air-fuel wing-shaped fin radiator(WFR)to further improve aerodynamic performance,load-bearing capacity and lightweight.The performance of WFR is validated by fluid-thermal-solid coupling method.From this study,it is revealed that the WFR structure respectively reduces the aerodynamic loss by 44.58%and 28.45%and the mass by 16.48%and 13.64%while ensuring the thermal efficiency,compared with structures of the frequently-used rectangular fin radiator and wing-rectangle fin radiator.The WFR is demonstrated to have excellent aerodynamic performance,high heat dissipation and light weight.The efforts of this study develop a promising WFR structure and provide an insight to support the high-performance and lightweight design of advanced aeroengines.展开更多
This article presents a general formulation for the mathematical modeling of a specific class of aerial robots known as hexacopters.The mentioned robotic system,which consists of six arms with motors attached to each ...This article presents a general formulation for the mathematical modeling of a specific class of aerial robots known as hexacopters.The mentioned robotic system,which consists of six arms with motors attached to each end,possesses a unique feature:it uses the minimum actuator required to reach a specific position in space with a defined orientation.To achieve this,it is vital to install the motors with an appropriate arrangement positioned at the end of each arm to ensure the robot’s controllability.On the other hand,two virtual arms with zero lengths were used to describe the robot’s orientation with regard to the inertial coordinate system in a tangible manner.One of the innovations carried out in this article is the standardization of the derivation of the motion equations of this robotic system procedure.For this purpose,first,the platform of the hexacopter is separated into several substructures.Following the previous step,the dynamic equations of each of these infrastructures are extracted in explicit form accordingly.Finally,the symbolic equations are merged,and as a result,the dynamic behavior of this aerial robot is formulated.The focus of this research is mainly on hexacopters.However,the presented method is generic enough to cover all aerial robots of this kind(with any number of arms and any relative arrangement between the members).Lastly,to show the robot’s ability to reach a specific position in space with the desired orientation,the results of tracking a relatively complex trajectory by utilizing this robotic system are presented.展开更多
The adaptive cycle engine(ACE)is considered a crucial candidate for the propulsion systems of next-generation aircraft.Its high thrust and low fuel consumption operating modes make it suitable for various flight missi...The adaptive cycle engine(ACE)is considered a crucial candidate for the propulsion systems of next-generation aircraft.Its high thrust and low fuel consumption operating modes make it suitable for various flight missions.However,the complex couplings and novel components in the ACE pose significant challenges to its performance design.This paper presents a systematic literature review on development status and performance deign of ACEs.Firstly,the development of ACE at various periods over the past few decades is presented.Then,four typical ACE configurations are introduced and analyzed based the differences of the core and the low-pressure compression system.After that,an emphasis is placed on the performance optimization method for ACE under various operating conditions,including steadystate,mode transition,acceleration/deceleration,and considering uncertainties.In addition,the numerical zooming technology for non-rotating components,rotating components,as well as intake and exhaust system are summarized in this paper.Through the above summary and analysis,the development trends in ACE performance design are explored.展开更多
Non-Newtonian flows have applications in food combination,plasma flow,inherent and organic fluids,antibiotics,and lubrication through oils and greases.This study explores the bidirectional flow of Williamson nanofluid...Non-Newtonian flows have applications in food combination,plasma flow,inherent and organic fluids,antibiotics,and lubrication through oils and greases.This study explores the bidirectional flow of Williamson nanofluid in a porous medium,incorporating thermophoresis,Brownian motion,bioconvection effects,and Arrhenius activation energy over a nonlinear stretching surface.The governing equations are transformed into a dimension-less form using similarity transformations and numerically solved via MATLAB’s bvp4c shooting scheme.Results indicate that increasing the Williamson parameterλand porosity parameterεreduces velocity,with a 10%rise inλleading to an 8%velocity reduction.Tem-perature increases with the thermophoresis parameter(Nt)where a 15%increase in Nt results in a 7%temperature rise.The Nusselt number improves with a higher Prandtl number Pr increasing by 10%when Pr rises from 5 to 7,while the Sherwood number declines with stron-ger Brownian motion.These findings provide key insights into heat and mass transfer Recent advances in modified Arrhenius activation energy and bioconvection mechanisms,contributing to advancements in industrial cooling,biomedical applications,and nanofluid-based thermal systems.展开更多
Radiators are used as a kind of heat exchanger to advance the performance of internal combustion engines by cooling different engine parts.Traditionally,water,ethylene glycol,engine oil,and their blends have been exte...Radiators are used as a kind of heat exchanger to advance the performance of internal combustion engines by cooling different engine parts.Traditionally,water,ethylene glycol,engine oil,and their blends have been extensively used in radiators for improvement in thermal and lubrication characteristics.However,with recent advancements in technology,nanofluids have emerged as promising coolant alternatives due to their enhanced thermophysical properties.This study provides a comprehensive review of current developments in mono,hybrid,and ternary nanofluids and their applications in automotive radiators.Further,the variation of the thermophysical properties of nanofluids,the preparation methods of nanofluids,the stability of nanofluids,strategies for improving the stability of the prepared fluids,and several empirical correlations for estimating thermophysical properties are discussed.Finally,the review study discusses the future direction of research in this field and shares insights into how to develop an efficient cooling system for engineering applications(especially automobile radiators).The key findings of the review study are as follows:(1)Hybrid nanofluids have generally shown superior performance in enhancing thermal conductivity and heat transfer coefficient due to their synergetic effects than mono nanofluids.For example,hybrid nanofluids,such as CuO-MgO-TiO_(2)in water blends,show an improvement in thermal conductivity up to 50.78%at a concentration of 0.5%and a temperature of 50℃.(2)Nanofluids can show stable behavior with minimal sedimentation for up to 30 days after preparation,even without the use of surfactants at lower concentrations.However,noticeable particle settling can be notice between 30 and 45 days.The addition of the surfactant sodium dodecylbenzene sulphonate ensures stability for over 3 months without visible sedimentation in the MWCNTs-based nanofluids.(3)Einstein's model does not generally provide reasonable predictions for the viscosity ratio of nanofluids,as it neglects the effect of particle shape and size.展开更多
Propulsion motors are essential for driving underwater platforms,which are de-signed to explore and exploit marine resources,primarily materials located within oceans and other bodies of water.Historically,humans have...Propulsion motors are essential for driving underwater platforms,which are de-signed to explore and exploit marine resources,primarily materials located within oceans and other bodies of water.Historically,humans have used artificial underwater structures such as ships,oil rigs,boats,submarines,robots,and autonomous vehicles to harness marine resources,encompassing commercial and military applications.Whether static or dynamic,these underwater platforms rely on different propulsion systems for manoeuvrability,including nuclear power,diesel engines,fuel cell/air independent propulsion(AIP)and elec-trically driven motors.These propulsion systems create thrust,using propeller or water jet mechanisms to move inside waterbodies.This study traces the evolution of underwater pro-pulsion motors in deep-sea applications from their inception to the current state-of-the-art advancements.It provides a detailed overview of existing underwater motor and controller technologies used for underwater platforms,emphasising their capabilities and limitations while highlighting potential areas for innovation in the design of multiphase motors.This paper critically evaluates the current electric propulsion motors used in underwater plat-forms.Furthermore,the paper identifies gaps in existing technologies for multiphase electric motors designed for deep-sea application,which are more than a hundred meters deep with power requirements exceeding 200 kW with the motor mounted externally,directly exposed to the high pressures of the deep-sea environment,setting the stage for future research and development opportunities that can lead to improved exploration of oceans and their re-sources.展开更多
The major concern of proffered study based on the inquisitive analysis of entropy approach based on 3-D Prandtl fluid influenced by modified advanced heat conduction along with mass diffusion models.Moreover,influence...The major concern of proffered study based on the inquisitive analysis of entropy approach based on 3-D Prandtl fluid influenced by modified advanced heat conduction along with mass diffusion models.Moreover,influence of Hall and also slip forces and heat transmission characteristics are featured under the combined outcomes appertaining to radiations and viscous dissipation are taken into account in this investigation.This article also examined the combined impacts of thermal conductivity change together with variable mass diffusion co-efficient within the heat and mass transport in the occurrence of Prandtl fluid.Flow demeanor is examined across the bidirectional extendable sheet.Numerical simulations based on 3-D flow configured by extending surface are carried out by using OHAM.Simulated PDEs expressed as ODEs with the utilization of dimensionless variables.Simulated outcomes are validated graphically obtained by varying values of emerging constraints through previous published results and seen in desirable agreement.The influence of distinct parameters associated with this current study like Brownian and diffusion constraint,temperature and also concentration difference,Eckert number,Hall as well as ion slip parameters,Brinkman number,magnetic constraint,radiation and Prandtl fluid constraint are sketched for temperature,velocity field along xy-axes,concentration and entropy generation rate.It is noticed that velocity distribution along x-axes is an increasing function of magnetic constraint,Prandtl fluid and also elastic constraint whilst contrast impact is seen along y-axes.Moreover,temperature as well as concentration profile decays for Prandtl number,thermal and also concentration relaxation time constraint respectively whereas both profiles enhanced for distinct considered parameters.Entropy declines for ion-slip parameter whilst enhanced for Bejan number.Entropy behavior as well as Bejan number effect under various parameters is sketched graphically and enhanced behavior is depicted for entropy for considered constraint whilst Bejan number enhanced for diffusion parameter and also concentration difference constraint whereas declined behavior demonstrated for other considered parameters.The innovative component in the current study lies in the integration of multiple factors towards the Prandtl fluid model framework,forcing its boundaries beyond widespread conventional applications.Extending the Prandtl fluid model in 3D allows more comprehensive demonstration of the under consideration physical system.展开更多
The prime focus of this article is to formulate and inspect the mathematical model concerning the bioconvective swirling stagnation point flow of magnetized Maxwell nanofluid in the presence of gyrotactic motile micro...The prime focus of this article is to formulate and inspect the mathematical model concerning the bioconvective swirling stagnation point flow of magnetized Maxwell nanofluid in the presence of gyrotactic motile microorganisms through a stretchable rotating disk.For the articulation of the heat transfer process,Fourier’s law of heat conduction is implemented by incorporating heat sources and thermal radiation.The flow is further accompanied by the activation energy and solutal boundary conditions.The flow behavior for velocity,thermal,concentration,and microorganisms’volumetric density profiles are discussed in detail.Furthermore,heat and mass fluxes are explored by considering thermophoresis impact and Brownian movement through the Buongiorno model.The governing complicated nonlinear partial differential equations of flow are reduced into dimension-free ordinary differential equations by introducing some appropriate transformation variables.This problem is computed numerically by deploying the bvp4c built-in function in MATLAB.The impacts of concerned flow describing parameters are assessed by utilizing both graphical and tabulated approaches.The results elucidate the flow toward radial and azimuthal directions accelerated by increasing the stretching ratio parameter but decelerated by enlarging the magnetic field parameter.The thermal field strengthens against the increasing thermal radiation parameter,thermophoresis parameter,heat source parameters,and the thermal Biot number.The nanoparticles concentration profile is boosted for increasing magnitudes of thermophoresis number and solutal Biot number while it diminishes for enlarging Brownian movement parameter.The gyrotactic motile microorganisms’profile is downscaled by the Peclet and bioconvection Lewis numbers whereas an adverse tendency is noticed against the microorganism Biot number.展开更多
An implicit finite difference(FD)and artificial neural network(ANN)tech-niques are applied to study the triple diffusion and non-linear mixed convection flow around a vertical cone.The forced flow is due to an impulsi...An implicit finite difference(FD)and artificial neural network(ANN)tech-niques are applied to study the triple diffusion and non-linear mixed convection flow around a vertical cone.The forced flow is due to an impulsive motion of a micropolar nanofluid while the buoyancy-driven flow is obtained using the quadratic form of Boussinesq approx-imation.Two governing equations are introduced for the species concentrations;those include non-linear chemical reactions.It is focused on the cases of the weak concentration of microelements,opposing and assisting flow,and the roles of the magnetic field,viscous dissipation,and convective boundary conditions are examined.The solution methodology is based on Mangler’s transformations.At the same time,the effective ANN is used to predict some important physical quantities such as heat transfer rate against some key factors such as Biot number,Eckert number,and magnetic coefficient.Remarkably,the flow rate in the assisting flow is up to 0.95%higher than in the opposing flow.Across all cases,an increase in the vortex parameter(K Z 0:1-1:2)enhances fluid friction near the cone surface by 63.1%.These findings are particularly relevant for industrial applications involving heat and mass transfer in nanofluid systems,such as microreactors,biomedical engineering,and thermal energy storage.展开更多
This study proposes a quantitative evaluation framework to assess the performance of boundary layer injection(BLI)technology,establishing standardized metrics for integration into performance analysis of scramjets.We ...This study proposes a quantitative evaluation framework to assess the performance of boundary layer injection(BLI)technology,establishing standardized metrics for integration into performance analysis of scramjets.We comparatively evaluate inert gas and fuel BLI strategies under typical combustor inflow conditions through systematic numerical investigations employing this evaluation framework.Key findings reveal that fuel injection demonstrates superior skin friction reduction efficacy compared to inert gases,especially hydrogen,achieving skin friction reduction performance up to 600 s at Mach 8+conditions with an injection equivalence ratio(ER)of 0.1.Hydrogen’s advantage arises from its inherently low density,coupled with combustion-induced density reduction in the log-law region.This dual mechanism suppresses turbulent momentum transport and attenuates skin friction through large-scale flow restructuring.However,when benchmarked against reacting mainstream flows without BLI,fuel injection efficacy diminishes significantly(100 s level)—local density reduction effects induced by boundary layer combustion are attenuated by mainstream heat release,limiting further momentum transport suppression and reducing drag reduction performance to inert gas levels.These results underscore the critical influence of ambient combustion conditions on BLI effectiveness,emphasizing that BLI implementation must prioritize non-reacting or weakly reacting flow environments.The proposed standardized metrics address this operational dependency,enabling BLI optimization within full-engine design paradigms to prevent counterproductive“pseudo-optimization.”展开更多
Compressor instability,particularly stall and surge,poses significant challenges to the performance,efficiency,and reliability of axial compressors in aerospace and power-generation systems.This review comprehensively...Compressor instability,particularly stall and surge,poses significant challenges to the performance,efficiency,and reliability of axial compressors in aerospace and power-generation systems.This review comprehensively summarizes the evolution of research on stall precursors,including modal wave,spike,rotating instability,and partial surge.Each pre-cursor exhibits distinct spatial and temporal characteristics linked to specific unsteady flow structures such as tip leakage vortex breakdown,hub corner separation,and shock-boundary layer interactions.The transformation of stall precursors under varying design parameters and operating conditions is analyzed,with a focus on how radial loading distribution,tip clear-ance,and inlet distortion influence instability behavior.Future directions are proposed,empha-sizing the development of unified theoretical models,accelerated numerical methods,and full-annulus experiments to enhance stall prediction and active control strategies.展开更多
In the presented paper,the size-dependent flutter analysis of a nanobeam made of metal-ceramic functionally graded(FG)materials subjected to supersonic fluid flow is examined.The volume fractions of metal and ceramic ...In the presented paper,the size-dependent flutter analysis of a nanobeam made of metal-ceramic functionally graded(FG)materials subjected to supersonic fluid flow is examined.The volume fractions of metal and ceramic vary along both longitudinal and thickness directions.The size effects are modeled based on the nonlocal strain gradient theory(NSGT)and the surface effects are included according to the Gurtin-Murdoch surface elasticity theory.The mathematical modeling of nanobeam is performed in the framework of Reddy’s third-order shear deformation beam theory(TSDBT),and the aerodynamic pressure is modeled according to the linear approximation of the piston theory.The governing equations and boundary conditions are obtained utilizing Hamilton’s principle and are solved approximately via the differential quadrature method(DQM).Convergence and precision of the presented work are proved and the effects of several parameters on the flutter boundaries are inspected such as material gradation indexes,nonlocal and strain gradient parameters,thickness-to-length ratio,and incorporation of surface effects.It is discovered that the incorporation of the surface effects has a remarkable impact on the flutter boundaries of nanobeams and increases both critical aerodynamic pressure and flutter frequency of the nanobeam.The aim of this work is to examine how the aeroelastic stability characteristics of an FG nanobeam can be affected by the nonlocal and strain gradient parameters and the variations in the volume fractions of the metal and ceramic in the longitudinal and thickness directions.展开更多
Fluid flow and transmission of heat have grown in importance in technology nowadays,and development is necessary to raise the technology standard to be on track with current advancements.This work,therefore,attempts t...Fluid flow and transmission of heat have grown in importance in technology nowadays,and development is necessary to raise the technology standard to be on track with current advancements.This work,therefore,attempts to ascertain the effects on fluid flow and transmission of heat across a permeable horizontal shrinking/stretching sheet of the viscous dissipation,and the temperature and velocity slip parameters.Dusty hybrid nanofluids were developed by scaterring copper and alumina nanoparticles along with dust particles into water.The programmed solver in MATLAB,referred to as bvp4c,has been utilized to generate numerical results of the similarity equations produced by simplifying the governing equations using the boundary layer approximation and the similarity transformation approach.The findings show that the rise in Eckert number lowers the heat transfer efficiency by 62.82%for the first solution.Interestingly,the Nusselt number becomes negative in the presence of viscous dissipation for the first and second solutions,with the influence of slip parameters,suggesting that heat is transferred from the fluid to the surface.Additionally,for certain values of shrinking surfaces,dual solutions are achievable.Thus,to sum up,modifying the parameters such as viscous dissipation and slip parameters significantly impacts the rate of heat transmission.展开更多
Fossil fuels have been the conventional source of energy that has driven economic growth and industrial development for a long time.However,their extensive use has led to immense environmental problems,especially conc...Fossil fuels have been the conventional source of energy that has driven economic growth and industrial development for a long time.However,their extensive use has led to immense environmental problems,especially concerning the emission of greenhouse gases.These problems have stimulated researchers to turn their attention to renewable alternative fuels.Hydrogen has risen in recent years as a prospective energy carrier because it is possible to produce it in an environmentally friendly manner and because it is the most common element.Hydrogen may be used in diesel engines in a dual-fuel mode.Hydrogen has a higher heating value,flame speed,and diffusivity in air.These superior fuel properties can enhance performance and combustion efficiency.Hydrogen can decrease carbon monoxide,unburned hydrocarbons,and soot emissions due to the absence of carbon in hydrogen.However,hydrogen-fuelled diesel engines have problems such as engine knocking and high nitrogen oxide emission.This paper presents a comprehensive review of the recent literature on the performance,combustion,and emission characteristics of hydrogen-fuelled diesel engines.Moreover,this paper discusses the long-term sustainability of hydrogen production methods,nitrogen oxide emission reduction techniques,challenges to the large-scale use of hydrogen,economic implications of hydrogen use,safety issues in hydrogen applications,regulations on hydrogen safety,conflicting NOx emission results in the literature,and material incompatibility issues in hydrogen applications.This study highlights state-of-the-art developments along with critical knowledge gaps that will be useful in guiding future research.These findings can support researchers and industry professionals in the integration of hydrogen into both existing and future diesel engine technologies.According to the literature,the use of hydrogen up to 46%decreased smoke emissions by over 75%,while CO_(2)and CO emissions significantly decreased.Moreover,hydrogen addition improved thermal efficiency up to 7.01%and decreased specific fuel consumption up to 7.19%.展开更多
The stability of nanofluid flow in a porous inclined channel with double diffusion and a magnetic field is investigated.The Darcy-Brinkman model is used to characterize fluid flow dynamics in porous medium.The analyti...The stability of nanofluid flow in a porous inclined channel with double diffusion and a magnetic field is investigated.The Darcy-Brinkman model is used to characterize fluid flow dynamics in porous medium.The analytical solutions are obtained for the unidirectional and completely developed flow.The perturbed state’s generalized eigenvalue problem is obtained using normal mode analysis.This eigenvalue problem is then solved using the spectral method.Key findings indicate that critical wavenumber and critical Rayleigh number,which determine the onset of instability,vary with different parameters.Specifically,an increase in the permeability,Soret parameter,thermo-solutal Lewis number,and Dufour parameter enhances system stability.Conversely,the inclination of the channel contribute to destabilizing the flow.Notably,the flow is most unstable when the channel is oriented vertically.展开更多
This article emphasises finding solutions for fluid flow and heat transfer-related problems through the Levenberg-Marquardt back-propagation technique.The solutions are developed for a three-layered channel with the p...This article emphasises finding solutions for fluid flow and heat transfer-related problems through the Levenberg-Marquardt back-propagation technique.The solutions are developed for a three-layered channel with the porous medium in the middle layer.The main motive of the numerical experiment is to investigate the parametric effects on the Cu-Al_(2)O_(3) hybrid nanofluid in the central layer,Cu nanofluid in the left layer and Al_(2)O_(3) nanofluid in the right layer.The training and testing data for generating the solution are sought through shooting technique.Levenberg-Marquardt back-propagation solutions show that the error for the training data is very close to zero.The computational domain is extended using a machine learning approach for various parametric values with zero Jacobian error.Results show that the slippery nature of the left wall has a noticeable effect in the hybrid nanofluid channel compared to the other layers.Also observed that the porosity decreases the velocity as the solid space dominates the fluid space and thus has a strong opposing force,reducing its velocity.展开更多
As the turbine inlet total temperature of the turbofan engine continues to increase,it is key to ensuring the long-term reliability of aeroengines that the components matching effectively to achieve the expected avera...As the turbine inlet total temperature of the turbofan engine continues to increase,it is key to ensuring the long-term reliability of aeroengines that the components matching effectively to achieve the expected average gas temperature.However,over temperature in turbine inlet is a common challenge in advanced engine development.To solve this problem,this paper proposes a new idea of a component matching optimization method to control average gas temperature.This method couples the optimization method with the adaptive performance model,which is built using accurate component characteristics and internal/external bypass mass flow rate within the engine test.Experiment methods of component characteristics measurement in different operating status under the condition of the whole engine are also developed,which capture the entire characteristics maps rather than the mini maps along the operating line.It also establishes calculation method of the core mass flow rate based on the critical characteristics of the high-pressure turbine.Tests have shown that by applying the component matching optimization method,the turbine inlet average gas temperature of a high-performance twin-spool mixed turbofan engine was reduced by 50 Ke60 K under the same thrust,ensuring fulfillment of the performance indexes.展开更多
Low pressure ratio fans of modern civil turbofans suffer from reduced stall margin in the take-off operating line and at part-speed,requiring variable geometry devices.Variable area nozzles(VAN)are one of the investig...Low pressure ratio fans of modern civil turbofans suffer from reduced stall margin in the take-off operating line and at part-speed,requiring variable geometry devices.Variable area nozzles(VAN)are one of the investigated solutions to control engine operating conditions throughout the mission.In this paper,we present a multi-fidelity modelling approach for an ultra-high bypass ratio turbofan engine with a VAN,combining a zero-dimensional thermody-namic cycle simulator using a realistic fan map with two-and three-dimensional detailed computational fluid dynamics(CFD)simulations for internal/external flow coupling.By adopting a novel algorithm to match the cycle conditions to the CFD solutions,the propulsive performance of the turbofan is analysed in a reference aircraft mission.The numerical method captures the effect on thrust generation and nacelle drag,providing a more reliable estimation of the impact of VAN on engine operation and efficiency.Low-speed mission points are confirmed to be those that benefit the most from an enlarged fan nozzle area,with a possible improvement of 3%in terms of thrust and specific fuel consumption at take-off and approach using a 10%larger area,similarly predicted by both 2D and 3D models.A preliminary acous-tic evaluation based on semi-empirical noise models indicates a modest effect on noise emis-sions,with up to 1 dB reduction in microphone signature at the sideline for a nozzle area increased by 10%.展开更多
As the demand for wide-speed-range and long-endurance aircraft continues to grow,variable cycle engines have become a research hotspot due to their excellent multitask adaptability.However,traditional overall performa...As the demand for wide-speed-range and long-endurance aircraft continues to grow,variable cycle engines have become a research hotspot due to their excellent multitask adaptability.However,traditional overall performance simulation techniques face challenges when dealing with complex engine configurations,as they require solving largerscale and higher-dimensional computational problems.This results in decreased simulation efficiency and poorer convergence,making it difficult to meet the demands for rapid performance evaluation and optimization.Although existing overall performance surrogate models for engines offer notable computational advantages,they still suffer from high training costs,low prediction accuracy,and limited application scenarios.To address these issues,this paper proposes an engine overall performance surrogate model driven by both knowledge and data.This model innovatively incorporates fundamental physical laws and domain knowledge of the engine during training and application,transforming the traditional black-box surrogate model into a gray-box model with certain interpretability.This significantly enhances prediction accuracy and application flexibility.Numerical verification results using the adaptive cycle engine(one of the most complex variable cycle configurations)as the application object show that the proposed surrogate model not only effectively predicts engine performance with prediction errors controlled within 0.5%,but also significantly improves the convergence and computational efficiency of engine performance simulation models.When applied to engine performance optimization,it achieves a nearly 60-fold increase in computational speed compared to traditional optimization methods,with an optimization error of only 0.15%.This approach can be widely applied to various types of engines and supports more complex and diverse engineering needs,offering broad application prospects.展开更多
Boron-based solid fuel is considered advantageous for ducted rocket applications due to its high energy density and dual-stage combustion process.Nonetheless,its performance is constrained by the formation of a protec...Boron-based solid fuel is considered advantageous for ducted rocket applications due to its high energy density and dual-stage combustion process.Nonetheless,its performance is constrained by the formation of a protective boron oxide layer.In the current study,iron nanoparticles are incorporated into boron-based solid fuel to enhance boron's burning.Paraffin wax serves as the primary fuel and binder,while gaseous oxygen is used as an oxidizer.Four different solid fuel combinations were investigated in the experiment:pure paraffin wax,paraffin wax mixed with boron particles,and paraffin wax mixed with boron alongside 10%and 20%iron particles.The main effort of the research is to assess their combustion characteristics,focusing on regression rate and combustion efficiency.While the inclusion of 10%iron particles resulted in a decrease in the regression rate,it led to an improvement in combustion efficiency by reducing the residual active boron content in the condensed combustion product by~60%.Furthermore,it was observed that increasing the proportion of iron particles to 20%further enhanced combustion efficiency to approximately 4%.The entire assessment has been carried out using a lab-scale hybrid propellant ducted rocket motor configuration having an inlet duct on regenerative concept with the secondary combustor.In the present investigation oxygen is injected both in the primary and the secondary combustor,whereas in the existing actual/lab-scale ducted rockets,an energized air is introduced in the secondary combustor.It serves as an economical system for the preliminary investigation of solid fuel impregnated with boron particles.It is expected that the present study could prove valuable strategies for future applications of boron-based hybrid propellants in ducted rocket systems.展开更多
基金co-supported by National Natural Science Foundation of China(Grant No.52375237)China and National Science and Technology Major Project(Grant No.J2022-IV-0012),China.
文摘With the development of functional integration and compactness design for next generation aeroengine,the ineffective dissipation and utilization of excess heat is one of the key research topics.This paper develops a novel air-fuel wing-shaped fin radiator(WFR)to further improve aerodynamic performance,load-bearing capacity and lightweight.The performance of WFR is validated by fluid-thermal-solid coupling method.From this study,it is revealed that the WFR structure respectively reduces the aerodynamic loss by 44.58%and 28.45%and the mass by 16.48%and 13.64%while ensuring the thermal efficiency,compared with structures of the frequently-used rectangular fin radiator and wing-rectangle fin radiator.The WFR is demonstrated to have excellent aerodynamic performance,high heat dissipation and light weight.The efforts of this study develop a promising WFR structure and provide an insight to support the high-performance and lightweight design of advanced aeroengines.
文摘This article presents a general formulation for the mathematical modeling of a specific class of aerial robots known as hexacopters.The mentioned robotic system,which consists of six arms with motors attached to each end,possesses a unique feature:it uses the minimum actuator required to reach a specific position in space with a defined orientation.To achieve this,it is vital to install the motors with an appropriate arrangement positioned at the end of each arm to ensure the robot’s controllability.On the other hand,two virtual arms with zero lengths were used to describe the robot’s orientation with regard to the inertial coordinate system in a tangible manner.One of the innovations carried out in this article is the standardization of the derivation of the motion equations of this robotic system procedure.For this purpose,first,the platform of the hexacopter is separated into several substructures.Following the previous step,the dynamic equations of each of these infrastructures are extracted in explicit form accordingly.Finally,the symbolic equations are merged,and as a result,the dynamic behavior of this aerial robot is formulated.The focus of this research is mainly on hexacopters.However,the presented method is generic enough to cover all aerial robots of this kind(with any number of arms and any relative arrangement between the members).Lastly,to show the robot’s ability to reach a specific position in space with the desired orientation,the results of tracking a relatively complex trajectory by utilizing this robotic system are presented.
基金funded by National Natural Science Foundation of China(NSFC)under Grants(No.51776010)the Fundamental Research Funds for the Central Universities and the Stable support project of the State Key Laboratory(No.12700002024146001).
文摘The adaptive cycle engine(ACE)is considered a crucial candidate for the propulsion systems of next-generation aircraft.Its high thrust and low fuel consumption operating modes make it suitable for various flight missions.However,the complex couplings and novel components in the ACE pose significant challenges to its performance design.This paper presents a systematic literature review on development status and performance deign of ACEs.Firstly,the development of ACE at various periods over the past few decades is presented.Then,four typical ACE configurations are introduced and analyzed based the differences of the core and the low-pressure compression system.After that,an emphasis is placed on the performance optimization method for ACE under various operating conditions,including steadystate,mode transition,acceleration/deceleration,and considering uncertainties.In addition,the numerical zooming technology for non-rotating components,rotating components,as well as intake and exhaust system are summarized in this paper.Through the above summary and analysis,the development trends in ACE performance design are explored.
基金supported by the Deanship of Scientific Research,Vice Presidency for Graduate Studies and Scientific Research,King Faisal University,Saudi Arabia(Grant No.252032).
文摘Non-Newtonian flows have applications in food combination,plasma flow,inherent and organic fluids,antibiotics,and lubrication through oils and greases.This study explores the bidirectional flow of Williamson nanofluid in a porous medium,incorporating thermophoresis,Brownian motion,bioconvection effects,and Arrhenius activation energy over a nonlinear stretching surface.The governing equations are transformed into a dimension-less form using similarity transformations and numerically solved via MATLAB’s bvp4c shooting scheme.Results indicate that increasing the Williamson parameterλand porosity parameterεreduces velocity,with a 10%rise inλleading to an 8%velocity reduction.Tem-perature increases with the thermophoresis parameter(Nt)where a 15%increase in Nt results in a 7%temperature rise.The Nusselt number improves with a higher Prandtl number Pr increasing by 10%when Pr rises from 5 to 7,while the Sherwood number declines with stron-ger Brownian motion.These findings provide key insights into heat and mass transfer Recent advances in modified Arrhenius activation energy and bioconvection mechanisms,contributing to advancements in industrial cooling,biomedical applications,and nanofluid-based thermal systems.
文摘Radiators are used as a kind of heat exchanger to advance the performance of internal combustion engines by cooling different engine parts.Traditionally,water,ethylene glycol,engine oil,and their blends have been extensively used in radiators for improvement in thermal and lubrication characteristics.However,with recent advancements in technology,nanofluids have emerged as promising coolant alternatives due to their enhanced thermophysical properties.This study provides a comprehensive review of current developments in mono,hybrid,and ternary nanofluids and their applications in automotive radiators.Further,the variation of the thermophysical properties of nanofluids,the preparation methods of nanofluids,the stability of nanofluids,strategies for improving the stability of the prepared fluids,and several empirical correlations for estimating thermophysical properties are discussed.Finally,the review study discusses the future direction of research in this field and shares insights into how to develop an efficient cooling system for engineering applications(especially automobile radiators).The key findings of the review study are as follows:(1)Hybrid nanofluids have generally shown superior performance in enhancing thermal conductivity and heat transfer coefficient due to their synergetic effects than mono nanofluids.For example,hybrid nanofluids,such as CuO-MgO-TiO_(2)in water blends,show an improvement in thermal conductivity up to 50.78%at a concentration of 0.5%and a temperature of 50℃.(2)Nanofluids can show stable behavior with minimal sedimentation for up to 30 days after preparation,even without the use of surfactants at lower concentrations.However,noticeable particle settling can be notice between 30 and 45 days.The addition of the surfactant sodium dodecylbenzene sulphonate ensures stability for over 3 months without visible sedimentation in the MWCNTs-based nanofluids.(3)Einstein's model does not generally provide reasonable predictions for the viscosity ratio of nanofluids,as it neglects the effect of particle shape and size.
文摘Propulsion motors are essential for driving underwater platforms,which are de-signed to explore and exploit marine resources,primarily materials located within oceans and other bodies of water.Historically,humans have used artificial underwater structures such as ships,oil rigs,boats,submarines,robots,and autonomous vehicles to harness marine resources,encompassing commercial and military applications.Whether static or dynamic,these underwater platforms rely on different propulsion systems for manoeuvrability,including nuclear power,diesel engines,fuel cell/air independent propulsion(AIP)and elec-trically driven motors.These propulsion systems create thrust,using propeller or water jet mechanisms to move inside waterbodies.This study traces the evolution of underwater pro-pulsion motors in deep-sea applications from their inception to the current state-of-the-art advancements.It provides a detailed overview of existing underwater motor and controller technologies used for underwater platforms,emphasising their capabilities and limitations while highlighting potential areas for innovation in the design of multiphase motors.This paper critically evaluates the current electric propulsion motors used in underwater plat-forms.Furthermore,the paper identifies gaps in existing technologies for multiphase electric motors designed for deep-sea application,which are more than a hundred meters deep with power requirements exceeding 200 kW with the motor mounted externally,directly exposed to the high pressures of the deep-sea environment,setting the stage for future research and development opportunities that can lead to improved exploration of oceans and their re-sources.
文摘The major concern of proffered study based on the inquisitive analysis of entropy approach based on 3-D Prandtl fluid influenced by modified advanced heat conduction along with mass diffusion models.Moreover,influence of Hall and also slip forces and heat transmission characteristics are featured under the combined outcomes appertaining to radiations and viscous dissipation are taken into account in this investigation.This article also examined the combined impacts of thermal conductivity change together with variable mass diffusion co-efficient within the heat and mass transport in the occurrence of Prandtl fluid.Flow demeanor is examined across the bidirectional extendable sheet.Numerical simulations based on 3-D flow configured by extending surface are carried out by using OHAM.Simulated PDEs expressed as ODEs with the utilization of dimensionless variables.Simulated outcomes are validated graphically obtained by varying values of emerging constraints through previous published results and seen in desirable agreement.The influence of distinct parameters associated with this current study like Brownian and diffusion constraint,temperature and also concentration difference,Eckert number,Hall as well as ion slip parameters,Brinkman number,magnetic constraint,radiation and Prandtl fluid constraint are sketched for temperature,velocity field along xy-axes,concentration and entropy generation rate.It is noticed that velocity distribution along x-axes is an increasing function of magnetic constraint,Prandtl fluid and also elastic constraint whilst contrast impact is seen along y-axes.Moreover,temperature as well as concentration profile decays for Prandtl number,thermal and also concentration relaxation time constraint respectively whereas both profiles enhanced for distinct considered parameters.Entropy declines for ion-slip parameter whilst enhanced for Bejan number.Entropy behavior as well as Bejan number effect under various parameters is sketched graphically and enhanced behavior is depicted for entropy for considered constraint whilst Bejan number enhanced for diffusion parameter and also concentration difference constraint whereas declined behavior demonstrated for other considered parameters.The innovative component in the current study lies in the integration of multiple factors towards the Prandtl fluid model framework,forcing its boundaries beyond widespread conventional applications.Extending the Prandtl fluid model in 3D allows more comprehensive demonstration of the under consideration physical system.
文摘The prime focus of this article is to formulate and inspect the mathematical model concerning the bioconvective swirling stagnation point flow of magnetized Maxwell nanofluid in the presence of gyrotactic motile microorganisms through a stretchable rotating disk.For the articulation of the heat transfer process,Fourier’s law of heat conduction is implemented by incorporating heat sources and thermal radiation.The flow is further accompanied by the activation energy and solutal boundary conditions.The flow behavior for velocity,thermal,concentration,and microorganisms’volumetric density profiles are discussed in detail.Furthermore,heat and mass fluxes are explored by considering thermophoresis impact and Brownian movement through the Buongiorno model.The governing complicated nonlinear partial differential equations of flow are reduced into dimension-free ordinary differential equations by introducing some appropriate transformation variables.This problem is computed numerically by deploying the bvp4c built-in function in MATLAB.The impacts of concerned flow describing parameters are assessed by utilizing both graphical and tabulated approaches.The results elucidate the flow toward radial and azimuthal directions accelerated by increasing the stretching ratio parameter but decelerated by enlarging the magnetic field parameter.The thermal field strengthens against the increasing thermal radiation parameter,thermophoresis parameter,heat source parameters,and the thermal Biot number.The nanoparticles concentration profile is boosted for increasing magnitudes of thermophoresis number and solutal Biot number while it diminishes for enlarging Brownian movement parameter.The gyrotactic motile microorganisms’profile is downscaled by the Peclet and bioconvection Lewis numbers whereas an adverse tendency is noticed against the microorganism Biot number.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/111/46.
文摘An implicit finite difference(FD)and artificial neural network(ANN)tech-niques are applied to study the triple diffusion and non-linear mixed convection flow around a vertical cone.The forced flow is due to an impulsive motion of a micropolar nanofluid while the buoyancy-driven flow is obtained using the quadratic form of Boussinesq approx-imation.Two governing equations are introduced for the species concentrations;those include non-linear chemical reactions.It is focused on the cases of the weak concentration of microelements,opposing and assisting flow,and the roles of the magnetic field,viscous dissipation,and convective boundary conditions are examined.The solution methodology is based on Mangler’s transformations.At the same time,the effective ANN is used to predict some important physical quantities such as heat transfer rate against some key factors such as Biot number,Eckert number,and magnetic coefficient.Remarkably,the flow rate in the assisting flow is up to 0.95%higher than in the opposing flow.Across all cases,an increase in the vortex parameter(K Z 0:1-1:2)enhances fluid friction near the cone surface by 63.1%.These findings are particularly relevant for industrial applications involving heat and mass transfer in nanofluid systems,such as microreactors,biomedical engineering,and thermal energy storage.
基金supported by the National Key Laboratory of Ramjet,Beijing Power Machinery Research Institute,Beijing,China.(No.WDZC6142703202202).
文摘This study proposes a quantitative evaluation framework to assess the performance of boundary layer injection(BLI)technology,establishing standardized metrics for integration into performance analysis of scramjets.We comparatively evaluate inert gas and fuel BLI strategies under typical combustor inflow conditions through systematic numerical investigations employing this evaluation framework.Key findings reveal that fuel injection demonstrates superior skin friction reduction efficacy compared to inert gases,especially hydrogen,achieving skin friction reduction performance up to 600 s at Mach 8+conditions with an injection equivalence ratio(ER)of 0.1.Hydrogen’s advantage arises from its inherently low density,coupled with combustion-induced density reduction in the log-law region.This dual mechanism suppresses turbulent momentum transport and attenuates skin friction through large-scale flow restructuring.However,when benchmarked against reacting mainstream flows without BLI,fuel injection efficacy diminishes significantly(100 s level)—local density reduction effects induced by boundary layer combustion are attenuated by mainstream heat release,limiting further momentum transport suppression and reducing drag reduction performance to inert gas levels.These results underscore the critical influence of ambient combustion conditions on BLI effectiveness,emphasizing that BLI implementation must prioritize non-reacting or weakly reacting flow environments.The proposed standardized metrics address this operational dependency,enabling BLI optimization within full-engine design paradigms to prevent counterproductive“pseudo-optimization.”
文摘Compressor instability,particularly stall and surge,poses significant challenges to the performance,efficiency,and reliability of axial compressors in aerospace and power-generation systems.This review comprehensively summarizes the evolution of research on stall precursors,including modal wave,spike,rotating instability,and partial surge.Each pre-cursor exhibits distinct spatial and temporal characteristics linked to specific unsteady flow structures such as tip leakage vortex breakdown,hub corner separation,and shock-boundary layer interactions.The transformation of stall precursors under varying design parameters and operating conditions is analyzed,with a focus on how radial loading distribution,tip clear-ance,and inlet distortion influence instability behavior.Future directions are proposed,empha-sizing the development of unified theoretical models,accelerated numerical methods,and full-annulus experiments to enhance stall prediction and active control strategies.
文摘In the presented paper,the size-dependent flutter analysis of a nanobeam made of metal-ceramic functionally graded(FG)materials subjected to supersonic fluid flow is examined.The volume fractions of metal and ceramic vary along both longitudinal and thickness directions.The size effects are modeled based on the nonlocal strain gradient theory(NSGT)and the surface effects are included according to the Gurtin-Murdoch surface elasticity theory.The mathematical modeling of nanobeam is performed in the framework of Reddy’s third-order shear deformation beam theory(TSDBT),and the aerodynamic pressure is modeled according to the linear approximation of the piston theory.The governing equations and boundary conditions are obtained utilizing Hamilton’s principle and are solved approximately via the differential quadrature method(DQM).Convergence and precision of the presented work are proved and the effects of several parameters on the flutter boundaries are inspected such as material gradation indexes,nonlocal and strain gradient parameters,thickness-to-length ratio,and incorporation of surface effects.It is discovered that the incorporation of the surface effects has a remarkable impact on the flutter boundaries of nanobeams and increases both critical aerodynamic pressure and flutter frequency of the nanobeam.The aim of this work is to examine how the aeroelastic stability characteristics of an FG nanobeam can be affected by the nonlocal and strain gradient parameters and the variations in the volume fractions of the metal and ceramic in the longitudinal and thickness directions.
基金funded by a Fundamental Research Grant Scheme(FRGS/1/2022/STG06/UITM/02/15)from the Ministry of Higher Education.
文摘Fluid flow and transmission of heat have grown in importance in technology nowadays,and development is necessary to raise the technology standard to be on track with current advancements.This work,therefore,attempts to ascertain the effects on fluid flow and transmission of heat across a permeable horizontal shrinking/stretching sheet of the viscous dissipation,and the temperature and velocity slip parameters.Dusty hybrid nanofluids were developed by scaterring copper and alumina nanoparticles along with dust particles into water.The programmed solver in MATLAB,referred to as bvp4c,has been utilized to generate numerical results of the similarity equations produced by simplifying the governing equations using the boundary layer approximation and the similarity transformation approach.The findings show that the rise in Eckert number lowers the heat transfer efficiency by 62.82%for the first solution.Interestingly,the Nusselt number becomes negative in the presence of viscous dissipation for the first and second solutions,with the influence of slip parameters,suggesting that heat is transferred from the fluid to the surface.Additionally,for certain values of shrinking surfaces,dual solutions are achievable.Thus,to sum up,modifying the parameters such as viscous dissipation and slip parameters significantly impacts the rate of heat transmission.
文摘Fossil fuels have been the conventional source of energy that has driven economic growth and industrial development for a long time.However,their extensive use has led to immense environmental problems,especially concerning the emission of greenhouse gases.These problems have stimulated researchers to turn their attention to renewable alternative fuels.Hydrogen has risen in recent years as a prospective energy carrier because it is possible to produce it in an environmentally friendly manner and because it is the most common element.Hydrogen may be used in diesel engines in a dual-fuel mode.Hydrogen has a higher heating value,flame speed,and diffusivity in air.These superior fuel properties can enhance performance and combustion efficiency.Hydrogen can decrease carbon monoxide,unburned hydrocarbons,and soot emissions due to the absence of carbon in hydrogen.However,hydrogen-fuelled diesel engines have problems such as engine knocking and high nitrogen oxide emission.This paper presents a comprehensive review of the recent literature on the performance,combustion,and emission characteristics of hydrogen-fuelled diesel engines.Moreover,this paper discusses the long-term sustainability of hydrogen production methods,nitrogen oxide emission reduction techniques,challenges to the large-scale use of hydrogen,economic implications of hydrogen use,safety issues in hydrogen applications,regulations on hydrogen safety,conflicting NOx emission results in the literature,and material incompatibility issues in hydrogen applications.This study highlights state-of-the-art developments along with critical knowledge gaps that will be useful in guiding future research.These findings can support researchers and industry professionals in the integration of hydrogen into both existing and future diesel engine technologies.According to the literature,the use of hydrogen up to 46%decreased smoke emissions by over 75%,while CO_(2)and CO emissions significantly decreased.Moreover,hydrogen addition improved thermal efficiency up to 7.01%and decreased specific fuel consumption up to 7.19%.
文摘The stability of nanofluid flow in a porous inclined channel with double diffusion and a magnetic field is investigated.The Darcy-Brinkman model is used to characterize fluid flow dynamics in porous medium.The analytical solutions are obtained for the unidirectional and completely developed flow.The perturbed state’s generalized eigenvalue problem is obtained using normal mode analysis.This eigenvalue problem is then solved using the spectral method.Key findings indicate that critical wavenumber and critical Rayleigh number,which determine the onset of instability,vary with different parameters.Specifically,an increase in the permeability,Soret parameter,thermo-solutal Lewis number,and Dufour parameter enhances system stability.Conversely,the inclination of the channel contribute to destabilizing the flow.Notably,the flow is most unstable when the channel is oriented vertically.
文摘This article emphasises finding solutions for fluid flow and heat transfer-related problems through the Levenberg-Marquardt back-propagation technique.The solutions are developed for a three-layered channel with the porous medium in the middle layer.The main motive of the numerical experiment is to investigate the parametric effects on the Cu-Al_(2)O_(3) hybrid nanofluid in the central layer,Cu nanofluid in the left layer and Al_(2)O_(3) nanofluid in the right layer.The training and testing data for generating the solution are sought through shooting technique.Levenberg-Marquardt back-propagation solutions show that the error for the training data is very close to zero.The computational domain is extended using a machine learning approach for various parametric values with zero Jacobian error.Results show that the slippery nature of the left wall has a noticeable effect in the hybrid nanofluid channel compared to the other layers.Also observed that the porosity decreases the velocity as the solid space dominates the fluid space and thus has a strong opposing force,reducing its velocity.
文摘As the turbine inlet total temperature of the turbofan engine continues to increase,it is key to ensuring the long-term reliability of aeroengines that the components matching effectively to achieve the expected average gas temperature.However,over temperature in turbine inlet is a common challenge in advanced engine development.To solve this problem,this paper proposes a new idea of a component matching optimization method to control average gas temperature.This method couples the optimization method with the adaptive performance model,which is built using accurate component characteristics and internal/external bypass mass flow rate within the engine test.Experiment methods of component characteristics measurement in different operating status under the condition of the whole engine are also developed,which capture the entire characteristics maps rather than the mini maps along the operating line.It also establishes calculation method of the core mass flow rate based on the critical characteristics of the high-pressure turbine.Tests have shown that by applying the component matching optimization method,the turbine inlet average gas temperature of a high-performance twin-spool mixed turbofan engine was reduced by 50 Ke60 K under the same thrust,ensuring fulfillment of the performance indexes.
文摘Low pressure ratio fans of modern civil turbofans suffer from reduced stall margin in the take-off operating line and at part-speed,requiring variable geometry devices.Variable area nozzles(VAN)are one of the investigated solutions to control engine operating conditions throughout the mission.In this paper,we present a multi-fidelity modelling approach for an ultra-high bypass ratio turbofan engine with a VAN,combining a zero-dimensional thermody-namic cycle simulator using a realistic fan map with two-and three-dimensional detailed computational fluid dynamics(CFD)simulations for internal/external flow coupling.By adopting a novel algorithm to match the cycle conditions to the CFD solutions,the propulsive performance of the turbofan is analysed in a reference aircraft mission.The numerical method captures the effect on thrust generation and nacelle drag,providing a more reliable estimation of the impact of VAN on engine operation and efficiency.Low-speed mission points are confirmed to be those that benefit the most from an enlarged fan nozzle area,with a possible improvement of 3%in terms of thrust and specific fuel consumption at take-off and approach using a 10%larger area,similarly predicted by both 2D and 3D models.A preliminary acous-tic evaluation based on semi-empirical noise models indicates a modest effect on noise emis-sions,with up to 1 dB reduction in microphone signature at the sideline for a nozzle area increased by 10%.
基金funded by National Natural Science Foundation of China under Grants 52406006,Fund Project 127000020241460012024-CXPT-GF-JJ-88-0001Supported by National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics and the Outstanding Research Project of Shen Yuan Honors College,BUAA(230123208).
文摘As the demand for wide-speed-range and long-endurance aircraft continues to grow,variable cycle engines have become a research hotspot due to their excellent multitask adaptability.However,traditional overall performance simulation techniques face challenges when dealing with complex engine configurations,as they require solving largerscale and higher-dimensional computational problems.This results in decreased simulation efficiency and poorer convergence,making it difficult to meet the demands for rapid performance evaluation and optimization.Although existing overall performance surrogate models for engines offer notable computational advantages,they still suffer from high training costs,low prediction accuracy,and limited application scenarios.To address these issues,this paper proposes an engine overall performance surrogate model driven by both knowledge and data.This model innovatively incorporates fundamental physical laws and domain knowledge of the engine during training and application,transforming the traditional black-box surrogate model into a gray-box model with certain interpretability.This significantly enhances prediction accuracy and application flexibility.Numerical verification results using the adaptive cycle engine(one of the most complex variable cycle configurations)as the application object show that the proposed surrogate model not only effectively predicts engine performance with prediction errors controlled within 0.5%,but also significantly improves the convergence and computational efficiency of engine performance simulation models.When applied to engine performance optimization,it achieves a nearly 60-fold increase in computational speed compared to traditional optimization methods,with an optimization error of only 0.15%.This approach can be widely applied to various types of engines and supports more complex and diverse engineering needs,offering broad application prospects.
基金the Centre of Excellence in Propulsion Systems,Alliance University,Bangalore,for providing funds(Grant No.-AU/DeanR/RC/2022)。
文摘Boron-based solid fuel is considered advantageous for ducted rocket applications due to its high energy density and dual-stage combustion process.Nonetheless,its performance is constrained by the formation of a protective boron oxide layer.In the current study,iron nanoparticles are incorporated into boron-based solid fuel to enhance boron's burning.Paraffin wax serves as the primary fuel and binder,while gaseous oxygen is used as an oxidizer.Four different solid fuel combinations were investigated in the experiment:pure paraffin wax,paraffin wax mixed with boron particles,and paraffin wax mixed with boron alongside 10%and 20%iron particles.The main effort of the research is to assess their combustion characteristics,focusing on regression rate and combustion efficiency.While the inclusion of 10%iron particles resulted in a decrease in the regression rate,it led to an improvement in combustion efficiency by reducing the residual active boron content in the condensed combustion product by~60%.Furthermore,it was observed that increasing the proportion of iron particles to 20%further enhanced combustion efficiency to approximately 4%.The entire assessment has been carried out using a lab-scale hybrid propellant ducted rocket motor configuration having an inlet duct on regenerative concept with the secondary combustor.In the present investigation oxygen is injected both in the primary and the secondary combustor,whereas in the existing actual/lab-scale ducted rockets,an energized air is introduced in the secondary combustor.It serves as an economical system for the preliminary investigation of solid fuel impregnated with boron particles.It is expected that the present study could prove valuable strategies for future applications of boron-based hybrid propellants in ducted rocket systems.
