Based on the piston theory of supersonic flow and the energy method, the flutter motion equations of a two-dimensional wing with cubic stiffness in the pitching direction are established. The aeroelastic system contai...Based on the piston theory of supersonic flow and the energy method, the flutter motion equations of a two-dimensional wing with cubic stiffness in the pitching direction are established. The aeroelastic system contains both structural and aerodynamic nonlinearities. Hopf bifurcation theory is used to analyze the flutter speed of the system. The effects of system parameters on the flutter speed are studied. The 4th order Runge-Kutta method is used to calculate the stable limit cycle responses and chaotic motions of the aeroelastic system. Results show that the number and the stability of equilibrium points of the system vary with the increase of flow speed. Besides the simple limit cycle response of period 1, there are also period-doubling responses and chaotic motions in the flutter system. The route leading to chaos in the aeroelastic model used here is the period-doubling bifurcation. The chaotic motions in the system occur only when the flow speed is higher than the linear divergent speed and the initial condition is very small. Moreover, the flow speed regions in which the system behaves chaos axe very narrow.展开更多
The present paper proposes a Lagrangian criterion of unsteady flow separation for two-dimensional periodic flows based on the principle of weighted averaging zero skin-friction given by Haller （HALLER, G. Exact theor...The present paper proposes a Lagrangian criterion of unsteady flow separation for two-dimensional periodic flows based on the principle of weighted averaging zero skin-friction given by Haller （HALLER, G. Exact theory of unsteady separation for two-dimensional flows. Journal of Fluid Mechanics, 512, 257-311 （2004））. By analyzing the distribution of the finite-time Lyapunov exponent （FTLE） along the no-slip wall, it can be found that the periodic separation takes place at the point of the zero FTLE. This new criterion is verified with an analytical solution of the separation bubble and a numerical simulation of lid-driven cavity flows.展开更多
The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personn...The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.展开更多
The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous...The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous challenges.In this work,a doping-free strategy is investigated by top gated(TG)MoS_(2) field-effect transistors(FETs)using various metal gates(Au,Cu,Ag,and Al).These metals with different work functions provide a convenient tuning knob for controlling threshold voltage(V_(th))for MoS_(2) FETs.For instance,the Al electrode can create an extra electron doping(n-doping)behavior in the MoS_(2) TG-FETs due to a dipole effect at the gate-dielectric interface.In this work,by achieving matched electrical properties for the load transistor and the driver transistor in an inverter circuit,we successfully demonstrate wafer-scale MoS_(2) inverter arrays with an optimized inverter switching threshold voltage(V_(M))of 1.5 V and a DC voltage gain of 27 at a supply voltage(V_(DD))of 3 V.This work offers a novel scheme for the fabrication of fully integrated multistage logic circuits based on wafer-scale MoS_(2) film.展开更多
An experimental investigation was performed to investigate two-dimensional axial velocity field at downstream of the 90°double bend pipe with and without inlet swirling condition. The main objectives are to fi...An experimental investigation was performed to investigate two-dimensional axial velocity field at downstream of the 90°double bend pipe with and without inlet swirling condition. The main objectives are to find separation region and observe the influence of inlet swirling flow on the velocity fluctuation using ultrasound technique. The experiments were carried out in the pipe at Reynolds number Re = 1 × 104. In case of inlet swirling flow condition, a rotary swirler was used as swirling generator, and the swirl number was setup S = 1. The ultrasonic measurements were taken at four downstream locations of the second bend pipe. Phased Array Ultrasonic Velocity Profiler (Phased Array UVP) technique was applied to obtain the two-dimensional velocity of the fluid and the axial and tangential velocity fluctuation. It was found that the secondary reverse flow became smaller at the downstream from the bend when the inlet condition on the first bend was swirling flow. In addition, inlet swirling condition influenced mainly on the tangential velocity fluctuation, and its maximum turbulence intensity was 40%.展开更多
To reduce computational costs, an improved form of the frequency domain boundary element method（BEM） is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitr...To reduce computational costs, an improved form of the frequency domain boundary element method（BEM） is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitrary orientation. The boundary integral equation（BIE） representation solves the two-dimensional convected Helmholtz equation（CHE） and its fundamental solution, which must satisfy a new Sommerfeld radiation condition（SRC） in the physical space. In order to facilitate conventional formulations, the variables of the advanced form are expressed only in terms of the acoustic pressure as well as its normal and tangential derivatives, and their multiplication operators are based on the convected Green＇s kernel and its modified derivative. The proposed approach significantly reduces the CPU times of classical computational codes for modeling acoustic domains with arbitrary mean flow. It is validated by a comparison with the analytical solutions for the sound radiation problems of monopole,dipole and quadrupole sources in the presence of a subsonic uniform flow with arbitrary orientation.展开更多
We study the effects of the perpendicular magnetic and Aharonov-Bohm （AB） flux fields on the energy levels of a two-dimensional （2D） Klein Gordon （KG） particle subjected to an equal scalar and vector pseudo-harm...We study the effects of the perpendicular magnetic and Aharonov-Bohm （AB） flux fields on the energy levels of a two-dimensional （2D） Klein Gordon （KG） particle subjected to an equal scalar and vector pseudo-harmonic oscillator （PHO）. We calculate the exact energy eigenvalues and normalized wave functions in terms of chemical potential param- eter, magnetic field strength, AB flux field, and magnetic quantum number by means of the Nikiforov Uvarov （NU） method. The non-relativistic limit, PHO, and harmonic oscillator solutions in the existence and absence of external fields are also obtained.展开更多
Materials that are difficult to cut,such as titanium alloys,are widely used in large load-bearing integral components of aircraft,leading to great challenges for manufacturing.Electrochemical milling is a way for mach...Materials that are difficult to cut,such as titanium alloys,are widely used in large load-bearing integral components of aircraft,leading to great challenges for manufacturing.Electrochemical milling is a way for machining difficult-to-cut materials through Computer Numerical Control(CNC)trajectory motion.Using a tilted large cathode machining surface and the cut-in feed mode,an efficient and low-cost method is obtained for machining the large integral components.A novel crossed and inclined structure of the flow mode is designed to realize electrochemical milling with a large tilted cathode surface.Compared to the vertical flow mode with one inlet,the proposed flow mode has two inlets that independently supply electrolytes,and the inclined channels make the flow field more stable.Flow field simulations are performed for both the vertical and proposed flow modes.The results show that the proposed flow mode avoids the random diversion of electrolytes and the ultralow flow velocity at both ends of the nozzle area,improving the velocity,uniformity,and stability of the electrolytes.The inclination angle of the crossed and inclined flow field is optimized.Finally,limit feed rate experiments are conducted in two modes,and the limit feed rate is 70 mm/min in the proposed mode.A sector workpiece of a large circular surface with approximately 8.77 mm thickness is machined 9 times by the cut-in electrochemical milling,the material removal rate is 4872 mm^(3)/min,and the surface roughness is superior to 1.15μm.展开更多
In electrochemical machining(ECM),the electrolyte flow field has a significant effect on machining stability,efficiency,and surface quality.In multitool ECM of blisk channels,the traditional open outflow mode(OOM)is p...In electrochemical machining(ECM),the electrolyte flow field has a significant effect on machining stability,efficiency,and surface quality.In multitool ECM of blisk channels,the traditional open outflow mode(OOM)is prone to flow randomness,the flow direction is not easy to control,and electrolytes interfere with each other,which causes problems with the normal conduct of machining.To improve the flow field distribution of multitool ECM,this paper proposes a constrained composite outflow mode(COM).The machining area is divided into separate isolated partitions by specific fixtures,which also provide back-pressure to the machining area.The electrolyte is injected into the machining gap and then flows out through the top and side outlets of the fixture.The flow field distribution during the process is simulated and analyzed using computational fluid dynamics.The simulation results show that the optimized flow mode improves the accessibility of the electrolyte and the uniformity of the flow distribution.ECM experiments are carried out using a specific fixture.With COM,the maximum feed rate of the cathode reaches 1.0 mm/min,and a channel with surface roughness Ra=1.54μm is machined.The suitability and effectiveness of the flow field simulation optimization are thus verified.On this basis,synchronous ECM of 15 channels is successfully realized,and the machining efficiency is found to be improved exponentially.展开更多
Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated ...Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated pellets,so that the energy consumption per ton of magnesium produced is reduced by 30∼40%,and the carbon emission is reduced by 43∼52%,breaking through the vacuum conditions to achieve continuous production.However,in the process of industrialization,it was found that the magnesium yield in the condenser was low.Therefore,this paper constructs a condenser model of relative vacuum continuous magnesium refining process,and comprehensively analyzes the condensation mechanism of magnesium vapor through simulation and experiment.It is found that the dynamic characteristics of magnesium vapor condensation is an important index to measure its continuity.Under the condition offlowing argon as the protective gas,when the condensation plate spacing is 10 cm,the surface roughness amplitude variance is 2,and the carrier gasflow rate is 20×10^(-3) m/s,the magnesium vapor has a better condensation effect,and the condensation efficiency formula is derived.展开更多
Controlling molten steel flow in the mold and stabilizing the meniscus are critical challenges during the continuous casting,directly impacting the surface quality and internal quality of the final steel slab product....Controlling molten steel flow in the mold and stabilizing the meniscus are critical challenges during the continuous casting,directly impacting the surface quality and internal quality of the final steel slab product.The effects of electromagnetic swirling flow in nozzle(EMSFN)technology on molten steel flow in the mold during slab continuous casting under various casting speeds were investigated.A real-time adjustable EMSFN was developed,and a three-dimensional unsteady Reynolds-averaged Navier–Stokes turbulence mathematical model was established to simulate the flow field within the mold.The results demonstrate that the EMSFN effectively stabilizes the outflow from nozzle,reduces the impact depth and surface velocity of the molten steel,mitigates meniscus fluctuations,and promotes stable flow within the mold.However,a certain matching relationship exists between the casting speed and the current intensity.For the experimental medium-thick slab specifications,the optimal current intensities were found to be 100,130,and 200 A at casting speeds of 1.0,1.5,and 2.0 m/min,respectively.EMSFN can optimize the mold flow field under different casting speeds,providing theoretical support for improving the quality of continuously cast slab products.展开更多
To advance the performance of solid oxide fuel cells(SOFCs),this work proposes a novel biomimetic flow field architecture inspired by the geometric arrangement of sunflower florets.Drawing on natural principles of opt...To advance the performance of solid oxide fuel cells(SOFCs),this work proposes a novel biomimetic flow field architecture inspired by the geometric arrangement of sunflower florets.Drawing on natural principles of optimal spatial distribution,a multi-physics simulation model of the resulting Sunflower Bionic Flow Field(SBFF)was developed.Building upon this foundation,an enhanced configuration was introduced by integrating an annular channel,yielding a modified variant referred to as Modified Sunflower Bionic Flow Field(MSBFF).For comparative purposes,a conventional Traditional Parallel Flow Field(TPFF)was also analyzed under identical conditions.Simulation results underscore the superior gas distribution performance of the bionic configurations.Both SBFF and MSBFF significantly improved the homogeneity of reactant gas molar concentration throughout the flow domain.Relative to the TPFF,the SBFF achieved a 13.32%increase in current density,while the MSBFF reached an enhancement of 15.09%.Correspondingly,peak power densities rose by 14.07%and 16.55%,respectively.Furthermore,these bio-inspired structures contributed to improved thermal regulation,as evidenced by a reduction in average electrolyte temperature by 3.22%for the SBFF and 2.92%for the MSBFF.To further optimize performance,the influence of Fibonacci spiral channel count within the MSBFF design was systematically investigated.Results reveal a strong positive correlation between the number of spiral channels and electrochemical output.In particular,the MSBFF with 16 spiral channels(MSBFF-16)demonstrated the most favorable electrical and thermal characteristics.At an operating voltage of 0.7 V,MSBFF-16 exhibited a current density increase of 1.27%and 0.94%over MSBFF and MSBFF-12,respectively.Likewise,peak power density improved by 2.69%and 1.67%.Finally,the study examined the impact of varying inlet mass fractions of oxygen and hydrogen on SOFC performance.Distinct trends were observed:increasing the oxygen mass fraction markedly enhanced heat transfer and current density,while greater hydrogen mass fractions significantly boosted fuel utilization.These findings highlight the crucial role of reactant composition and flow field topology in governing the electrochemical and thermal efficiency of SOFC systems.展开更多
Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearw...Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.展开更多
Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic...Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic flow field designs in recent literature with a focus on bionic flow fields.In particular,the bionic flow fields are summarized into two types:plant-inspired and animal-inspired.The conventional methodology for flow field design takes more time to find the optimum since it is based on experience and trial-and-error methods.In recent years,machine learning has been used to optimize flow field structures of bipolar plates owing to the advantages of excellent prediction and optimization capability.Artificial Intelligence(AI)-assisted flow field design has been summarized into two categories in this review:single-objective optimization and multi-objective optimization.Furthermore,a Threats-Opportunities-Weaknesses-Strengths(TOWS)analysis has been conducted for AI-assisted flow field design.It has been envisioned that AI can afford a powerful tool to solve the complex problem of bionic flow field design and significantly enhance the performance of PEMFC with bionic flow fields.展开更多
The numerical calculation method has greatly promoted the process of optimal design of scramjet,but it still needs extremely heavy calculation for the model with complex thermochemical reaction.Data-driven deep learni...The numerical calculation method has greatly promoted the process of optimal design of scramjet,but it still needs extremely heavy calculation for the model with complex thermochemical reaction.Data-driven deep learning relies heavily on a large amount of data in the face of complex nonlinear features.Therefore,combining“data-driven model”and“Navier-Stokes equation”,an intelligent prediction model of supersonic combustion flow process is constructed.This algorithm integrates the theory priors of combustion flow into the neural network model,and uses convolutional grouping and rearrangement to reduce the feature redundancy calculation,so as to achieve high-precision and high-efficiency prediction of velocity,density,pressure and temperature fields.This study makes a comprehensive comparison from two aspects of performance and efficiency.Unsteady scramjet multi-physical field dataset is constructed under different incoming Mach number conditions.The experimental results show that compared with other methods,the proposed algorithm can achieve the maximum Peak Signal-to-Noise Ratio(PSNR)improvement of 38.75%and Learned Perceptual Image Patch Similarity(LPIPS)improvement of 68.13%in predicting the average quality of images,and the computational cost of the model is reduced by 30.36%compared with other models.In addition,the high model can also effectively predict the unknown incoming flow condition.展开更多
The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary ...The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary cap.Due to the limited depth of borehole exploration,heat flow measurements and analyses of the Archean crystalline base-ment in the study area are rare.Further investigation of the heat flow and temperature field characteristics within the Archean crystalline basement beneath the karst geothermal reservoir is necessary to understand the vertical distribution of heat flow and improve the geothermal genetic mechanism in the area.The D01 deep geothermal scientific drilling param-eter well was implemented in the Niutuozhen geothermal field of Xiong'an New Area.The well exposed the entire Gaoyuzhaung Formation karst geotheremal reservoir of the Jixian system and drilled 1,723.67 m into the Archean crys-talline basement,providing the necessary conditions for determining its heat flow.This study involved borehole tempera-ture measurements and thermophysical property testing of core samples from the D01 well to analyze the vertical distri-bution of heat flow.The findings revealed distinct segmentation in the geothermal gradient and rock thermophysical prop-erties.The geothermal reservoir of Gaoyuzhuang Formation is dominated by convection,with significant temperature inversions corresponding to karst fracture developments.In contrast,the Archean crystalline basement exhibits conduc-tive heat transfer.After 233 days of static equilibrium,the average geothermal gradients of the Gaoyuzhuang Formation and the Archean crystalline basement were determined to be 1.5°C/km and 18.3°C/km,respectively.These values adjusted to-0.8°C/km and 18.2°C/km after 551 days,with the longer static time curve approaching steady-state condi-tions.The average thermal conductivity of dolomite in Gaoyuzhuang Formation was measured as 4.37±0.82 W/(K·m),3 and that of Archean gneiss as 2.41±0.40 W/(K·m).The average radioactive heat generation rate were 0.30±0.32μW/m 3 for dolomite and 1.32±0.69μW/m for gneiss.Using the temperature curve after 551 days and thermal conductivity data,the Archean heat flow at the D01 well was calculated as(43.9±7.0)mW/m2,While the heat flow for the Neogene sedi-mentary cap was estimated at 88.6mW/m2.The heat flow of Neogene sedimentary caprock is significantly higher than 2 that of Archean crystalline basement at the D01 well,with an excess of 44.7 mW/m accounting for approximately 50%of the total heat flow in the Neogene sedimentary caprock.This is primarily attributed to lateral thermal convection within the high-porosity and high-permeability karst dolomite layer,and vertical thermal convection facilitated by the Niudong fault,which collectively contribute to the heat supply of the Neogene sedimentary caprock.Thermal convection in karst fissure and fault zone contribute approximately 50%of the heat flow in the Neogene sedimentary caprock.This study quantitatively revealed the vertical distribution of heat flow,providing empirical evidence for the genetic mechanism of the convection-conduction geothermal system in sedimentary basins.展开更多
The development of all-electric,low-orbit satellite constellations requires low-power Hall thrusters with a wide thrust output.However,the efficiency at low flow rates decreases rapidly due to the deterioration of ion...The development of all-electric,low-orbit satellite constellations requires low-power Hall thrusters with a wide thrust output.However,the efficiency at low flow rates decreases rapidly due to the deterioration of ionization.Although magnetic fields are widely used to optimize Hall thrusters,they are rarely used in wide-range variable flow conditions.In this study,we investigate the influence of the magnetic field gradient on the flow-rate range experimentally.It is found that a small-gradient magnetic field is helpful to improve performance at low flow rates.Then,the experimental results are explained by theoretical deduction,and the quantitative relationship between the flow rate and gradient is given.These conclusions provide guidance and a theoretical basis for designing high-performance,wide-range Hall thrusters.展开更多
The complex flow characteristics of transverse jet in high-speed crossflow involve several separation regions and multiple shock waves,which make it difficult to capture and precisely predict the flow field state in r...The complex flow characteristics of transverse jet in high-speed crossflow involve several separation regions and multiple shock waves,which make it difficult to capture and precisely predict the flow field state in real time merely by relying on traditional approaches.With the rapid advancement of deep learning technology,its powerful data processing capability offers a fast method for the prediction of the transverse jet flow field.Consequently,a prediction model based on deep learning is established,with the aim of obtaining the flow characteristics of a transverse jet under different freestream and jet conditions.This study segments the complex grid into several individual grids and trains them independently.The trained model can successfully establish the nonlinear mapping relationship between the transverse jet flow field and the input parameters.The prediction accuracy of the established model for the wall pressure under different conditions exceeds 99%,and the established model is also capable of reproducing structures such as shock waves and recirculation zones in the overall flow field,thereby achieving highly precise and efficient prediction of the jet structure and flow information.The results suggest that in contrast to the traditional numerical simulation,this deep learning model demonstrates greater efficiency in predicting the transverse jet flow field.展开更多
Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD ...Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD technology.The flow field characteristics and rock breaking ability of cone-straight abrasive jet,rotary abrasive jet,and straight-rotating mixed abrasive jet are analyzed by numerical simulations and experiments.Results show that the axial velocity of the cone-straight abrasive jet is high,the tangential velocity is basically zero,the radial velocity is also small,and the jet impact area is concentrated in the center.A deep hole with a diameter of only 25 mm is formed when the cone-straight abrasive jet breaks the granite.Due to the presence of the guiding impeller,the rotary abrasive jet basically has no axial velocity and has the highest tangential and radial velocity,so it can break the granite to form a hole with a diameter of about 55 mm and a central bulge.The straight-rotating mixed abrasive jet has a large axial/tangential/radial velocity at the same time,so it can break the granite to form a hole with a diameter of about 52 mm with a low bulge.The results show that the straight-rotating mixed abrasive jet combines the advantages of the cone-straight jet and the rotary jet,and is more suitable for the RJD technology.The research results can provide reference for the development of efficient rock-breaking and hole-forming technology,and promote the development of RJD technology in the field of geothermal development.展开更多
High-Resolution(HR)data on flow fields are critical for accurately evaluating the aerodynamic performance of aircraft.However,acquiring such data through large-scale numerical simulations or wind tunnel experiments is...High-Resolution(HR)data on flow fields are critical for accurately evaluating the aerodynamic performance of aircraft.However,acquiring such data through large-scale numerical simulations or wind tunnel experiments is highly resource intensive.This paper proposes a FlowViT-Diff framework that integrates a Vision Transformer(ViT)with an enhanced denoising diffusion probabilistic model for the Super-Resolution(SR)reconstruction of HR flow fields based on low-resolution inputs.It provides a quick initial prediction of the HR flow field by optimizing the ViT architecture,and incorporates this preliminary output as guidance within an enhanced diffusion model.The latter captures the Gaussian noise distribution during forward diffusion and progressively removes it during backward diffusion to generate the flow field.Experiments on various supercritical airfoils under different flow conditions show that FlowViT-Diff can robustly reconstruct the flow field across multiple levels of downsampling.It obtains more consistent global and local features than traditional SR methods,and yields a 3.6-fold increase in its training speed via transfer learning.Its accuracy of reconstruction of the flow field is 99.7%under ultra-low downsampling.The results demonstrate that Flow Vi T-Diff not only exhibits effective flow field reconstruction capabilities,but also provides two reconstruction strategies,both of which show effective transferability.展开更多
基金supported by the National Natural Science Foundation of China and China Academy of Engineering Physics(No. 10576024).
文摘Based on the piston theory of supersonic flow and the energy method, the flutter motion equations of a two-dimensional wing with cubic stiffness in the pitching direction are established. The aeroelastic system contains both structural and aerodynamic nonlinearities. Hopf bifurcation theory is used to analyze the flutter speed of the system. The effects of system parameters on the flutter speed are studied. The 4th order Runge-Kutta method is used to calculate the stable limit cycle responses and chaotic motions of the aeroelastic system. Results show that the number and the stability of equilibrium points of the system vary with the increase of flow speed. Besides the simple limit cycle response of period 1, there are also period-doubling responses and chaotic motions in the flutter system. The route leading to chaos in the aeroelastic model used here is the period-doubling bifurcation. The chaotic motions in the system occur only when the flow speed is higher than the linear divergent speed and the initial condition is very small. Moreover, the flow speed regions in which the system behaves chaos axe very narrow.
基金supported by the National Natural Science Foundation of China(Nos.11372340 and 11732016)
文摘The present paper proposes a Lagrangian criterion of unsteady flow separation for two-dimensional periodic flows based on the principle of weighted averaging zero skin-friction given by Haller （HALLER, G. Exact theory of unsteady separation for two-dimensional flows. Journal of Fluid Mechanics, 512, 257-311 （2004））. By analyzing the distribution of the finite-time Lyapunov exponent （FTLE） along the no-slip wall, it can be found that the periodic separation takes place at the point of the zero FTLE. This new criterion is verified with an analytical solution of the separation bubble and a numerical simulation of lid-driven cavity flows.
基金supported by the National Natural Science Foundation of China(Grant No.U2341269)。
文摘The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.
基金supported by the National Key Research and Development Program (No.2016YFA0203900)Innovation Program of Shanghai Municipal Education Commission (No.2021–01–07–00–07-E00077)+1 种基金Shanghai Municipal Science and Technology Commission (No.21DZ1100900)National Natural Science Foundation of China (Nos.51802041,61904032,and 61874154)。
文摘The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous challenges.In this work,a doping-free strategy is investigated by top gated(TG)MoS_(2) field-effect transistors(FETs)using various metal gates(Au,Cu,Ag,and Al).These metals with different work functions provide a convenient tuning knob for controlling threshold voltage(V_(th))for MoS_(2) FETs.For instance,the Al electrode can create an extra electron doping(n-doping)behavior in the MoS_(2) TG-FETs due to a dipole effect at the gate-dielectric interface.In this work,by achieving matched electrical properties for the load transistor and the driver transistor in an inverter circuit,we successfully demonstrate wafer-scale MoS_(2) inverter arrays with an optimized inverter switching threshold voltage(V_(M))of 1.5 V and a DC voltage gain of 27 at a supply voltage(V_(DD))of 3 V.This work offers a novel scheme for the fabrication of fully integrated multistage logic circuits based on wafer-scale MoS_(2) film.
文摘An experimental investigation was performed to investigate two-dimensional axial velocity field at downstream of the 90°double bend pipe with and without inlet swirling condition. The main objectives are to find separation region and observe the influence of inlet swirling flow on the velocity fluctuation using ultrasound technique. The experiments were carried out in the pipe at Reynolds number Re = 1 × 104. In case of inlet swirling flow condition, a rotary swirler was used as swirling generator, and the swirl number was setup S = 1. The ultrasonic measurements were taken at four downstream locations of the second bend pipe. Phased Array Ultrasonic Velocity Profiler (Phased Array UVP) technique was applied to obtain the two-dimensional velocity of the fluid and the axial and tangential velocity fluctuation. It was found that the secondary reverse flow became smaller at the downstream from the bend when the inlet condition on the first bend was swirling flow. In addition, inlet swirling condition influenced mainly on the tangential velocity fluctuation, and its maximum turbulence intensity was 40%.
基金supported by National Engineering School of Tunis (No.13039.1)
文摘To reduce computational costs, an improved form of the frequency domain boundary element method（BEM） is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitrary orientation. The boundary integral equation（BIE） representation solves the two-dimensional convected Helmholtz equation（CHE） and its fundamental solution, which must satisfy a new Sommerfeld radiation condition（SRC） in the physical space. In order to facilitate conventional formulations, the variables of the advanced form are expressed only in terms of the acoustic pressure as well as its normal and tangential derivatives, and their multiplication operators are based on the convected Green＇s kernel and its modified derivative. The proposed approach significantly reduces the CPU times of classical computational codes for modeling acoustic domains with arbitrary mean flow. It is validated by a comparison with the analytical solutions for the sound radiation problems of monopole,dipole and quadrupole sources in the presence of a subsonic uniform flow with arbitrary orientation.
文摘We study the effects of the perpendicular magnetic and Aharonov-Bohm （AB） flux fields on the energy levels of a two-dimensional （2D） Klein Gordon （KG） particle subjected to an equal scalar and vector pseudo-harmonic oscillator （PHO）. We calculate the exact energy eigenvalues and normalized wave functions in terms of chemical potential param- eter, magnetic field strength, AB flux field, and magnetic quantum number by means of the Nikiforov Uvarov （NU） method. The non-relativistic limit, PHO, and harmonic oscillator solutions in the existence and absence of external fields are also obtained.
基金co-supported by National Natural Science Foundation of China(No.52075253)National Natural Science Foundation of China for Creative Research Groups(No.51921003).
文摘Materials that are difficult to cut,such as titanium alloys,are widely used in large load-bearing integral components of aircraft,leading to great challenges for manufacturing.Electrochemical milling is a way for machining difficult-to-cut materials through Computer Numerical Control(CNC)trajectory motion.Using a tilted large cathode machining surface and the cut-in feed mode,an efficient and low-cost method is obtained for machining the large integral components.A novel crossed and inclined structure of the flow mode is designed to realize electrochemical milling with a large tilted cathode surface.Compared to the vertical flow mode with one inlet,the proposed flow mode has two inlets that independently supply electrolytes,and the inclined channels make the flow field more stable.Flow field simulations are performed for both the vertical and proposed flow modes.The results show that the proposed flow mode avoids the random diversion of electrolytes and the ultralow flow velocity at both ends of the nozzle area,improving the velocity,uniformity,and stability of the electrolytes.The inclination angle of the crossed and inclined flow field is optimized.Finally,limit feed rate experiments are conducted in two modes,and the limit feed rate is 70 mm/min in the proposed mode.A sector workpiece of a large circular surface with approximately 8.77 mm thickness is machined 9 times by the cut-in electrochemical milling,the material removal rate is 4872 mm^(3)/min,and the surface roughness is superior to 1.15μm.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075253,51921003)the Industrial Technology Development Program(Grant No.JCKY2021605B026)。
文摘In electrochemical machining(ECM),the electrolyte flow field has a significant effect on machining stability,efficiency,and surface quality.In multitool ECM of blisk channels,the traditional open outflow mode(OOM)is prone to flow randomness,the flow direction is not easy to control,and electrolytes interfere with each other,which causes problems with the normal conduct of machining.To improve the flow field distribution of multitool ECM,this paper proposes a constrained composite outflow mode(COM).The machining area is divided into separate isolated partitions by specific fixtures,which also provide back-pressure to the machining area.The electrolyte is injected into the machining gap and then flows out through the top and side outlets of the fixture.The flow field distribution during the process is simulated and analyzed using computational fluid dynamics.The simulation results show that the optimized flow mode improves the accessibility of the electrolyte and the uniformity of the flow distribution.ECM experiments are carried out using a specific fixture.With COM,the maximum feed rate of the cathode reaches 1.0 mm/min,and a channel with surface roughness Ra=1.54μm is machined.The suitability and effectiveness of the flow field simulation optimization are thus verified.On this basis,synchronous ECM of 15 channels is successfully realized,and the machining efficiency is found to be improved exponentially.
基金the National Natural Science Foundation of China(U1908225,U1702253)the Special Funds for Ba-sic Research Operations of Central Universities(N182515007,N170908001,N2025004).
文摘Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated pellets,so that the energy consumption per ton of magnesium produced is reduced by 30∼40%,and the carbon emission is reduced by 43∼52%,breaking through the vacuum conditions to achieve continuous production.However,in the process of industrialization,it was found that the magnesium yield in the condenser was low.Therefore,this paper constructs a condenser model of relative vacuum continuous magnesium refining process,and comprehensively analyzes the condensation mechanism of magnesium vapor through simulation and experiment.It is found that the dynamic characteristics of magnesium vapor condensation is an important index to measure its continuity.Under the condition offlowing argon as the protective gas,when the condensation plate spacing is 10 cm,the surface roughness amplitude variance is 2,and the carrier gasflow rate is 20×10^(-3) m/s,the magnesium vapor has a better condensation effect,and the condensation efficiency formula is derived.
基金National Natural Science Foundation of China(Nos.U21A20117,52104347 and 52272078)the Fundamental Research Funds for the Central Universities(No.N2409006)Natural Science Foundation of Liaoning Province(2023-MSBA-135)for the financial support.
文摘Controlling molten steel flow in the mold and stabilizing the meniscus are critical challenges during the continuous casting,directly impacting the surface quality and internal quality of the final steel slab product.The effects of electromagnetic swirling flow in nozzle(EMSFN)technology on molten steel flow in the mold during slab continuous casting under various casting speeds were investigated.A real-time adjustable EMSFN was developed,and a three-dimensional unsteady Reynolds-averaged Navier–Stokes turbulence mathematical model was established to simulate the flow field within the mold.The results demonstrate that the EMSFN effectively stabilizes the outflow from nozzle,reduces the impact depth and surface velocity of the molten steel,mitigates meniscus fluctuations,and promotes stable flow within the mold.However,a certain matching relationship exists between the casting speed and the current intensity.For the experimental medium-thick slab specifications,the optimal current intensities were found to be 100,130,and 200 A at casting speeds of 1.0,1.5,and 2.0 m/min,respectively.EMSFN can optimize the mold flow field under different casting speeds,providing theoretical support for improving the quality of continuously cast slab products.
基金supported by a grant from National Key R&D Plan of China(Grant No.2023YFB2504503).
文摘To advance the performance of solid oxide fuel cells(SOFCs),this work proposes a novel biomimetic flow field architecture inspired by the geometric arrangement of sunflower florets.Drawing on natural principles of optimal spatial distribution,a multi-physics simulation model of the resulting Sunflower Bionic Flow Field(SBFF)was developed.Building upon this foundation,an enhanced configuration was introduced by integrating an annular channel,yielding a modified variant referred to as Modified Sunflower Bionic Flow Field(MSBFF).For comparative purposes,a conventional Traditional Parallel Flow Field(TPFF)was also analyzed under identical conditions.Simulation results underscore the superior gas distribution performance of the bionic configurations.Both SBFF and MSBFF significantly improved the homogeneity of reactant gas molar concentration throughout the flow domain.Relative to the TPFF,the SBFF achieved a 13.32%increase in current density,while the MSBFF reached an enhancement of 15.09%.Correspondingly,peak power densities rose by 14.07%and 16.55%,respectively.Furthermore,these bio-inspired structures contributed to improved thermal regulation,as evidenced by a reduction in average electrolyte temperature by 3.22%for the SBFF and 2.92%for the MSBFF.To further optimize performance,the influence of Fibonacci spiral channel count within the MSBFF design was systematically investigated.Results reveal a strong positive correlation between the number of spiral channels and electrochemical output.In particular,the MSBFF with 16 spiral channels(MSBFF-16)demonstrated the most favorable electrical and thermal characteristics.At an operating voltage of 0.7 V,MSBFF-16 exhibited a current density increase of 1.27%and 0.94%over MSBFF and MSBFF-12,respectively.Likewise,peak power density improved by 2.69%and 1.67%.Finally,the study examined the impact of varying inlet mass fractions of oxygen and hydrogen on SOFC performance.Distinct trends were observed:increasing the oxygen mass fraction markedly enhanced heat transfer and current density,while greater hydrogen mass fractions significantly boosted fuel utilization.These findings highlight the crucial role of reactant composition and flow field topology in governing the electrochemical and thermal efficiency of SOFC systems.
基金supported by National Natural Science Foundation of Joint Fund for Changjiang River Water Science Research(U2340201)National Natural Science Foundation of China(52239006)Natural Science Foundation of Sichuan Province(2024NSFSC0005).
文摘Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.
基金supported by the National Natural Science Foundation of China(52075214and 51975245)the National Key R&D Program of China(No.2022YFE0138500)+3 种基金Jilin Provincial Science&Technology Department(20220201115GX)Key Science and Technology R&D Projects of Jilin Province(2020C023-3)Program of Jilin University Science and Technology Innovative Research Team(2020TD-03)the Fundamental Research Funds for the Central Universities.
文摘Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic flow field designs in recent literature with a focus on bionic flow fields.In particular,the bionic flow fields are summarized into two types:plant-inspired and animal-inspired.The conventional methodology for flow field design takes more time to find the optimum since it is based on experience and trial-and-error methods.In recent years,machine learning has been used to optimize flow field structures of bipolar plates owing to the advantages of excellent prediction and optimization capability.Artificial Intelligence(AI)-assisted flow field design has been summarized into two categories in this review:single-objective optimization and multi-objective optimization.Furthermore,a Threats-Opportunities-Weaknesses-Strengths(TOWS)analysis has been conducted for AI-assisted flow field design.It has been envisioned that AI can afford a powerful tool to solve the complex problem of bionic flow field design and significantly enhance the performance of PEMFC with bionic flow fields.
基金supported by the Program of Key Projects of Foundation Strengthening Plan,China(No.2022-JCJQ-ZD114-12-03)the Graduate Student Innovation Fund Lighthouse Program of Southwest University of Science and Technology,China(No.24ycx3009)。
文摘The numerical calculation method has greatly promoted the process of optimal design of scramjet,but it still needs extremely heavy calculation for the model with complex thermochemical reaction.Data-driven deep learning relies heavily on a large amount of data in the face of complex nonlinear features.Therefore,combining“data-driven model”and“Navier-Stokes equation”,an intelligent prediction model of supersonic combustion flow process is constructed.This algorithm integrates the theory priors of combustion flow into the neural network model,and uses convolutional grouping and rearrangement to reduce the feature redundancy calculation,so as to achieve high-precision and high-efficiency prediction of velocity,density,pressure and temperature fields.This study makes a comprehensive comparison from two aspects of performance and efficiency.Unsteady scramjet multi-physical field dataset is constructed under different incoming Mach number conditions.The experimental results show that compared with other methods,the proposed algorithm can achieve the maximum Peak Signal-to-Noise Ratio(PSNR)improvement of 38.75%and Learned Perceptual Image Patch Similarity(LPIPS)improvement of 68.13%in predicting the average quality of images,and the computational cost of the model is reduced by 30.36%compared with other models.In addition,the high model can also effectively predict the unknown incoming flow condition.
基金funded by the National Key Research and Development Program(Grant Nos.2021YFB1507404 and 2018YFC0604305)the Project of China Geological Survey(Grant Nos.DD20221680,DD20189113,and DD20190127).
文摘The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary cap.Due to the limited depth of borehole exploration,heat flow measurements and analyses of the Archean crystalline base-ment in the study area are rare.Further investigation of the heat flow and temperature field characteristics within the Archean crystalline basement beneath the karst geothermal reservoir is necessary to understand the vertical distribution of heat flow and improve the geothermal genetic mechanism in the area.The D01 deep geothermal scientific drilling param-eter well was implemented in the Niutuozhen geothermal field of Xiong'an New Area.The well exposed the entire Gaoyuzhaung Formation karst geotheremal reservoir of the Jixian system and drilled 1,723.67 m into the Archean crys-talline basement,providing the necessary conditions for determining its heat flow.This study involved borehole tempera-ture measurements and thermophysical property testing of core samples from the D01 well to analyze the vertical distri-bution of heat flow.The findings revealed distinct segmentation in the geothermal gradient and rock thermophysical prop-erties.The geothermal reservoir of Gaoyuzhuang Formation is dominated by convection,with significant temperature inversions corresponding to karst fracture developments.In contrast,the Archean crystalline basement exhibits conduc-tive heat transfer.After 233 days of static equilibrium,the average geothermal gradients of the Gaoyuzhuang Formation and the Archean crystalline basement were determined to be 1.5°C/km and 18.3°C/km,respectively.These values adjusted to-0.8°C/km and 18.2°C/km after 551 days,with the longer static time curve approaching steady-state condi-tions.The average thermal conductivity of dolomite in Gaoyuzhuang Formation was measured as 4.37±0.82 W/(K·m),3 and that of Archean gneiss as 2.41±0.40 W/(K·m).The average radioactive heat generation rate were 0.30±0.32μW/m 3 for dolomite and 1.32±0.69μW/m for gneiss.Using the temperature curve after 551 days and thermal conductivity data,the Archean heat flow at the D01 well was calculated as(43.9±7.0)mW/m2,While the heat flow for the Neogene sedi-mentary cap was estimated at 88.6mW/m2.The heat flow of Neogene sedimentary caprock is significantly higher than 2 that of Archean crystalline basement at the D01 well,with an excess of 44.7 mW/m accounting for approximately 50%of the total heat flow in the Neogene sedimentary caprock.This is primarily attributed to lateral thermal convection within the high-porosity and high-permeability karst dolomite layer,and vertical thermal convection facilitated by the Niudong fault,which collectively contribute to the heat supply of the Neogene sedimentary caprock.Thermal convection in karst fissure and fault zone contribute approximately 50%of the heat flow in the Neogene sedimentary caprock.This study quantitatively revealed the vertical distribution of heat flow,providing empirical evidence for the genetic mechanism of the convection-conduction geothermal system in sedimentary basins.
基金funded by National Natural Science Foundation of China(Nos.52076054 and 51736003).
文摘The development of all-electric,low-orbit satellite constellations requires low-power Hall thrusters with a wide thrust output.However,the efficiency at low flow rates decreases rapidly due to the deterioration of ionization.Although magnetic fields are widely used to optimize Hall thrusters,they are rarely used in wide-range variable flow conditions.In this study,we investigate the influence of the magnetic field gradient on the flow-rate range experimentally.It is found that a small-gradient magnetic field is helpful to improve performance at low flow rates.Then,the experimental results are explained by theoretical deduction,and the quantitative relationship between the flow rate and gradient is given.These conclusions provide guidance and a theoretical basis for designing high-performance,wide-range Hall thrusters.
基金co-supported by the National Natural Science Foundation of China(No.12202488)the National Postdoctoral Researcher Program(Grants No.GZB20230985)+1 种基金the Natural Science Program of National University of Defense Technology(No.ZK22-30)the Independent Innovation Science Fund of National University of Defense Technology(No.24-ZZCX-BC-05)。
文摘The complex flow characteristics of transverse jet in high-speed crossflow involve several separation regions and multiple shock waves,which make it difficult to capture and precisely predict the flow field state in real time merely by relying on traditional approaches.With the rapid advancement of deep learning technology,its powerful data processing capability offers a fast method for the prediction of the transverse jet flow field.Consequently,a prediction model based on deep learning is established,with the aim of obtaining the flow characteristics of a transverse jet under different freestream and jet conditions.This study segments the complex grid into several individual grids and trains them independently.The trained model can successfully establish the nonlinear mapping relationship between the transverse jet flow field and the input parameters.The prediction accuracy of the established model for the wall pressure under different conditions exceeds 99%,and the established model is also capable of reproducing structures such as shock waves and recirculation zones in the overall flow field,thereby achieving highly precise and efficient prediction of the jet structure and flow information.The results suggest that in contrast to the traditional numerical simulation,this deep learning model demonstrates greater efficiency in predicting the transverse jet flow field.
基金funded by the National Natural Science Foundation of China(No.52374018)Science Foundation of China University of Petroleum,Beijing(No.2462021YJRC009)。
文摘Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD technology.The flow field characteristics and rock breaking ability of cone-straight abrasive jet,rotary abrasive jet,and straight-rotating mixed abrasive jet are analyzed by numerical simulations and experiments.Results show that the axial velocity of the cone-straight abrasive jet is high,the tangential velocity is basically zero,the radial velocity is also small,and the jet impact area is concentrated in the center.A deep hole with a diameter of only 25 mm is formed when the cone-straight abrasive jet breaks the granite.Due to the presence of the guiding impeller,the rotary abrasive jet basically has no axial velocity and has the highest tangential and radial velocity,so it can break the granite to form a hole with a diameter of about 55 mm and a central bulge.The straight-rotating mixed abrasive jet has a large axial/tangential/radial velocity at the same time,so it can break the granite to form a hole with a diameter of about 52 mm with a low bulge.The results show that the straight-rotating mixed abrasive jet combines the advantages of the cone-straight jet and the rotary jet,and is more suitable for the RJD technology.The research results can provide reference for the development of efficient rock-breaking and hole-forming technology,and promote the development of RJD technology in the field of geothermal development.
基金supported by the National Natural Science Foundation of China(No.12472265)。
文摘High-Resolution(HR)data on flow fields are critical for accurately evaluating the aerodynamic performance of aircraft.However,acquiring such data through large-scale numerical simulations or wind tunnel experiments is highly resource intensive.This paper proposes a FlowViT-Diff framework that integrates a Vision Transformer(ViT)with an enhanced denoising diffusion probabilistic model for the Super-Resolution(SR)reconstruction of HR flow fields based on low-resolution inputs.It provides a quick initial prediction of the HR flow field by optimizing the ViT architecture,and incorporates this preliminary output as guidance within an enhanced diffusion model.The latter captures the Gaussian noise distribution during forward diffusion and progressively removes it during backward diffusion to generate the flow field.Experiments on various supercritical airfoils under different flow conditions show that FlowViT-Diff can robustly reconstruct the flow field across multiple levels of downsampling.It obtains more consistent global and local features than traditional SR methods,and yields a 3.6-fold increase in its training speed via transfer learning.Its accuracy of reconstruction of the flow field is 99.7%under ultra-low downsampling.The results demonstrate that Flow Vi T-Diff not only exhibits effective flow field reconstruction capabilities,but also provides two reconstruction strategies,both of which show effective transferability.
