Although the thin and cold Martian atmosphere provides the feasibility of rotorcraft flight on Mars,rotors designed for denser Earth atmosphere with small angles of attack hardly generate enough thrust for rotorcraft ...Although the thin and cold Martian atmosphere provides the feasibility of rotorcraft flight on Mars,rotors designed for denser Earth atmosphere with small angles of attack hardly generate enough thrust for rotorcraft flight at conventional rotational speeds in the Martian atmosphere.In this paper,we employ the Particle Swarm Optimization(PSO)algorithm to search for the control points of the Bezier curve,completing the parameterization of the airfoil upper and lower curves based on these control points.In order to directly enhance the lift-to-drag ratio of the airfoil at high angles of attack,the NSGA-II algorithm is utilized to optimize the lift-to-drag ratio of NACA 6904 at a=17.5°,Ma=0.43,Re=7600,and CLF 5605 at a=15°,Ma=0.7,Re=7481,respectively.The two-dimensional RANS(Reynolds Average NavierStokes)and k-ωSST turbulence models are employed in the optimization process by CFD to predict the lift and drag characteristics of the airfoil in a Martian environment.Under simulated Mars atmospheric conditions(pressure of 1380 Pa,test temperature of 24°C,equivalent Mars atmospheric density at the surface of 0.0162 g/cm~3),the airfoil after optimized is subjected to rotor lift-drag characteristic tests where a single-rotor lift-drag characteristic test bench is employed for verification.The experimental results demonstrate that the RB-TB-II blade,which is obtained by optimizing the airfoil based on the RB-SWQ-I blade,exhibits a 19.6%increase in Power Loading(PL)and a 20.4%increase in Figure of Merit(FM)compared with the RB-SWQ-I blade.Based on the results of airfoil optimization,increasing the camber at the leading edge of the airfoil under high angles of attack contributes to an improved lift-to-drag ratio.展开更多
This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow con...This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.展开更多
Airfoil structures play a crucial role across numerous scientific and technological disciplines,with the transition to turbulence and stall onset remaining key challenges in aerodynamic research.While experimental tec...Airfoil structures play a crucial role across numerous scientific and technological disciplines,with the transition to turbulence and stall onset remaining key challenges in aerodynamic research.While experimental techniques often surpass numerical simulations in accuracy,they still present notable limitations.This paper begins by elucidating the fundamental principles of transition,dynamic stall,and airfoil behavior.It then provides a systematic reviewof six major experimentalmethodologies and examines the emerging role of artificial intelligence in this domain.By identifying key challenges and limitations,the study proposes strategic advancements to address these issues,offering a foundational framework to guide future research in airfoil structures and related fields.展开更多
This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared wit...This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared with a conventional pin fin heat sink with a circular profile.This study searched for the best thermo-hydraulic performance by translational and rotational positioning of the fins.It is worth mentioning that this work was carried out in two stages.In the first stage,the thermo-hydraulic behavior of the heat sink was studied moving the location of the upper array above the X-axis from to 2.25 mm and above the Y-axis from to 1.275 mm.The second stage examined-2.25-1.55the effects of fin rotation considering the results found in stage 1.However,in this second stage,both arrays were free to rotate.For the upper array,the rotation range was-25°to 25° and for the lower array the rotation range was-15° to 15°.It is worth mentioning that both stages were analyzed for a single Reynolds(Re)number value of 13,000.The optimization results using the multi-objective evolutionary algorithm showed that compared to a NACA 0040 heat sink with fixed,unrotated original configuration(C0),the NACA 0040 heat sink with any Position Configuration(PC)did not significantly improve the heat transfer.Then,the results found in the second stage showed that the effect of the rotation of both sets did not influence the increase in pressure drop.However,it was found that with the Optimal Position and Rotation Configuration(PRCoptimal),which is the optimized array from Stage 1(position)then optimized by rotation,there is a slightly higher Performance Evaluation Criterion(PEC)compared to the original C0 configuration by 7%.Finally,the proposed NACA 0040 heat sink with the optimal rotation and position setting(PRCoptimal)was found to have a PEC of 9%compared to a conventional pin fin heat sink.展开更多
Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its ef...Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its effectiveness and mechanism in delaying airfoil stall are investigated by numerical simulations.The herringbone groove array is placed on the airfoil's upper surface near the trailing edge,and the effects of groove depth and yaw angle on the control effect are investigated.The results demonstrate that different designs of herringbone groove array can effectively broaden the stable operating range of the airfoil,and the application of herringbone groove array with a depth of only 0.00135 times the chord length and a yaw angle of 45°can result in a28.57%increase in the stable operating range.The flow details indicate that a pair of induced vortices with the same strength and opposite direction are formed near the converging line under the combined action of the accumulation effect of small-scale vortices in the grooves and the spanwise migration flow above the grooves.The induced vortices increase the mixing between the main flow and the boundary layer,allowing the boundary layer to gain sufficient energy to withstand the adverse pressure gradient at high angles of attack,effectively delaying airfoil stall.展开更多
Recent advances in contrastive language-image pretraining(CLIP)models and generative AI have demonstrated significant capabilities in cross-modal understanding and content generation.Based on these developments,this s...Recent advances in contrastive language-image pretraining(CLIP)models and generative AI have demonstrated significant capabilities in cross-modal understanding and content generation.Based on these developments,this study introduces a novel framework for airfoil design via natural language interfaces.To the authors’knowledge,this study establishes the first end-to-end,bidirectional mapping between textual descriptions(e.g.,“low-drag supercritical wing for transonic conditions”)and parametric airfoil geometries represented by class-shape transformation parameters.The proposed approach integrates a CLIP-inspired architecture that aligns text embeddings with airfoil parameter spaces through contrastive learning,along with a semantically conditioned decoder that produces physically plausible airfoil geometries from latent representations.The experimental results validate the framework’s ability to generate aerodynamically plausible airfoils from natural language specifications and to classify airfoils accurately based on given textual labels.This research reduces the expertise threshold for preliminary airfoil design and highlights the potential for human-AI collaboration in aerospace engineering.展开更多
Generative adversarial network(GAN)models are widely used in mechanical designs.The aim in the airfoil shape design is to obtain shapes that exhibits the required aerodynamic performance,and conditional GAN is used fo...Generative adversarial network(GAN)models are widely used in mechanical designs.The aim in the airfoil shape design is to obtain shapes that exhibits the required aerodynamic performance,and conditional GAN is used for that aim.However,the output of GAN contains uncertainties.Additionally,the uncertainties of labels have not been quantified.This paper proposes an uncertainty quantification method to estimate the uncertainty of labels using Monte Carlo dropout.In addition,an uncertainty reduction method is proposed based on imbalanced training.The proposed method was evaluated for the airfoil generation task.The results indicated that the uncertainty was appropriately quantified and successfully reduced.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
To reduce the complexity of mixing systems and improve mixing efficiency,this paper proposes a valveless piezoelectric pump integrated with airfoil baffles,which embodies both active and passive mixing attributes.The ...To reduce the complexity of mixing systems and improve mixing efficiency,this paper proposes a valveless piezoelectric pump integrated with airfoil baffles,which embodies both active and passive mixing attributes.The airfoil baffles are designed using the asymmetric NACA63-412 profile.The impact of the airfoil angle of attack on the flow field within the tube and the output and mixing performance of the piezoelectric pump is investigated.Computational simulations of the tube with airfoil baffle indicated that as the angle of attack increases,the position of vortex generation at the leading and trailing edge regions of the airfoil baffle progressively moves forward in the direction of fluid flow.Then the vortex volume enlarges,and the vortex intensity within the flow field rises.Subsequently,the prototypes of valveless piezoelectric pumps at four different angles of attack are fabricated and their output performances are experimentally evaluated.The results demonstrate that the maximum output flow rate of the pump decreases with an increasing angle of attack.At an angle of attack of 0°,the maximum output flow rate of the pump reaches 225.3 ml/min.Mixing performance experiments are conducted using the piezoelectric pump for the synthesis of Fe_(3)O_(4)particles.The findings indicate that as the angle of attack increases,the number of Fe_(3)O_(4)particles formed in the mixture significantly rises,with a narrower particle size distribution and more regular morphology.At an angle of attack of 15°,the synthesized Fe_(3)O_(4)particles have an approximate diameter of 10μm.The outcomes of this paper offer valuable insights for the design of microfluidic systems,catering to the demands of material synthesis,chemistry,and biomedical applications.展开更多
Under complex flight conditions,such as obstacle avoidance and extreme sea state,wing-in-ground(WIG)effect aircraft need to ascend to higher altitudes,resulting in the disappearance of the ground effect.A design of hi...Under complex flight conditions,such as obstacle avoidance and extreme sea state,wing-in-ground(WIG)effect aircraft need to ascend to higher altitudes,resulting in the disappearance of the ground effect.A design of high-speed WIG airfoil considering non-ground effect is carried out by a novel two-step inverse airfoil design method that combines conditional generative adversarial network(CGAN)and artificial neural network(ANN).The CGAN model is employed to generate a variety of airfoil designs that satisfy the desired lift-drag ratios in both ground effect and non-ground effect conditions.Subsequently,the ANN model is utilized to forecast aerodynamic parameters of the generated airfoils.The results indicate that the CGAN model contributes to a high accuracy rate for airfoil design and enables the creation of novel airfoil designs.Furthermore,it demonstrates high accuracy in predicting aerodynamic parameters of these airfoils due to the ANN model.This method eliminates the necessity for numerical simulations and experimental testing through the design procedure,showcasing notable efficiency.The analysis of airfoils generated by the CGAN model shows that airfoils exhibiting high lift-drag ratios under both flight conditions typically have cambers of among[0.08c,0.105c],with the positions of maximum camber occurring among[0.35c,0.5c]of the chord length,and the leading-edge radiuses of these airfoils primarily cluster among[0.008c,0.025c]展开更多
The aerodynamic performance of wind turbine needs to be improved day by day.In this paper,the bionic airfoil of wind turbine and the traditional airfoil are combined to optimize the aerodynamic performance.The new air...The aerodynamic performance of wind turbine needs to be improved day by day.In this paper,the bionic airfoil of wind turbine and the traditional airfoil are combined to optimize the aerodynamic performance.The new airfoil is synthesized by the method of the mean camber line superposition thickness synthesis.The flow field characteristics of 4 synthetic airfoils were calculated by using the numerical simulation of CFD commercial software Fluent,and compared with 3 original airfoils,new airfoils of different shapes were obtained,and an incomplete synthetic parameterization method for airfoils optimization was proved,which has certain engineering practical value.展开更多
This article deals with an experimental study on the aerodynamic characteristics of a low-drag high-speed nature laminar flow (NLF) airfoil for business airplanes in the TST27 wind tunnel at Delft University of Techno...This article deals with an experimental study on the aerodynamic characteristics of a low-drag high-speed nature laminar flow (NLF) airfoil for business airplanes in the TST27 wind tunnel at Delft University of Technology, the Netherlands. In this experiment, in an attempt to reduce the errors of measurement and improve its accuracy in high-speed flight, some nonintrusive meas- urement techniques, such as the quantitative infrared thermography (IRT), the digital particle imaging velocimetry (PIV), and the s...展开更多
A transonic airfoil designed by means of classical point-optimization may result in its dramatically inferior performance under off-design conditions. To overcome this shortcoming, robust design is proposed to find ou...A transonic airfoil designed by means of classical point-optimization may result in its dramatically inferior performance under off-design conditions. To overcome this shortcoming, robust design is proposed to find out the optimal profile of an airfoil to maintain its performance in an uncertain environment. The robust airfoil optimization is aimed to minimize mean values and variances of drag coefficients while satisfying the lift and thickness constraints over a range of Mach numbers. A multi-objective estimation of distribution algorithm is applied to the robust airfoil optimization on the base of the RAE2822 benchmark airfoil. The shape of the airfoil is obtained through superposing ten Hick-Henne shape functions upon the benchmark airfoil. A set of design points is selected according to a uniform design table for aerodynamic evaluation. A Kriging model of drag coefficient is constructed with those points to reduce computing costs. Over the Mach range from 0.7 to 0.8, the airfoil generated by the robust optimization has a configuration characterized by supercritical airfoil with low drag coefficients. The small fluctuation in its drag coefficients means that the performance of the robust airfoil is insensitive to variation of Mach number.展开更多
For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grid...For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective.展开更多
To avoid the aerodynamic performance loss of airfoil at non-design state which often appears in single point design optimization, and to improve the adaptability to the uncertain factors in actual flight environment, ...To avoid the aerodynamic performance loss of airfoil at non-design state which often appears in single point design optimization, and to improve the adaptability to the uncertain factors in actual flight environment, a two-dimensional stochastic airfoil optimization design method based on neural networks is presented. To provide highly efficient and credible analysis, four BP neural networks are built as surrogate models to predict the airfoil aerodynamic coefficients and geometry parameter. These networks are combined with the probability density function obeying normal distribution and the genetic algorithm, thus forming an optimization design method. Using the method, for GA（W）-2 airfoil, a stochastic optimization is implemented in a two-dimensional flight area about Mach number and angle of attack. Compared with original airfoil and single point optimization design airfoil, results show that the two-dimensional stochastic method can improve the performance in a specific flight area, and increase the airfoil adaptability to the stochastic changes of multiple flight parameters.展开更多
In this paper, the effects of icing on an NACA 23012 airfoil have been studied. Exper- iments were applied on the clean airfoil, runback ice, horn ice, and spanwise ridge ice at a Reynolds number of 0.6 x 10^6 over an...In this paper, the effects of icing on an NACA 23012 airfoil have been studied. Exper- iments were applied on the clean airfoil, runback ice, horn ice, and spanwise ridge ice at a Reynolds number of 0.6 x 10^6 over angles of attack from -8° to 20% and then results are compared. Gener- ally, it is found that ice accretion on the airfoil can contribute to formation of a flow separation bubble on the upper surface downstream from the leading edge. In addition, it is made clear that spanwise ridge ice provides the greatest negative effect on the aerodynamic performance of the airfoil. In this case, the stall angle drops about 10^6 and the maximum lift coefficient reduces about 50% which is hazardous for an airplane. While horn ice leads to a stall angle drop of about 4°and a maximum lift coefficient reduction to 21%, runback ice has the least effect on the flow pattern around the airfoil and the aerodynamic coefficients so as the stall angle decreases 2% and the maximum lift reduces about 8%.展开更多
Abstract A transonic, high Reynolds number natural laminar flow airfoil is designed and studied. The γ-θ transition model is combined with the shear stress transport （SST） k-w turbulence model to predict the trans...Abstract A transonic, high Reynolds number natural laminar flow airfoil is designed and studied. The γ-θ transition model is combined with the shear stress transport （SST） k-w turbulence model to predict the transition region for a laminar-turbulent boundary layer. The non-uniform free-form deformation （NFFD） method based on the non-uniform rational B-spline （NURBS） basis function is introduced to the airfoil parameterization. The non-dominated sorting genetic algorithm-II （NSGA-II） is used as the search algo- rithm, and the surrogate model based on the Kriging models is introduced to improve the efficiency of the optimization system. The optimization system is set up based on the above technologies, and the robust design about the uncertainty of the Mach number is carried out for NASA0412 airfoil. The optimized airfoil is analyzed and compared with the original airfoil. The results show that natural laminar flow can be achieved on a supercritical airfoil to improve the aerodynamic characteristic of airfoils.展开更多
Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element ...Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element airfoil.Dual-objective optimization is carried out with critical hornshaped ice accumulated during the holding phase.The optimization results show that the present optimization method significantly enhances the iced-state and clean-state performance.The optimal multi-element airfoil has a larger deflection angle and wider gap at the slat and the flap compared with the baseline configuration.The sensitivity of each design parameter is analyzed,which verifies the robustness of the design.The design is further assessed when ice is accreted during the approach and landing phases,which also shows performance improvement.展开更多
In the present work,a parametric numerical study is conducted in order to assess the effect of airfoil cambering on the aerodynamic performance of rigid heaving airfoils.The incompressible Navier-Stokes equations are ...In the present work,a parametric numerical study is conducted in order to assess the effect of airfoil cambering on the aerodynamic performance of rigid heaving airfoils.The incompressible Navier-Stokes equations are solved in their velocity-pressure formulation using a second-order accurate in space and time finite-difference scheme.To tackle the problem of moving boundaries,the governing equations are solved on overlapping structured grids.The numerical simulations are performed at a Reynolds number of Re=1100 and at different values of Strouhal number and reduced frequency.The results obtained show that the airfoil cambering geometric parameter has a strong influence on the average lift coefficient,while it has a smaller impact on the average thrust coefficient and propulsive efficiency of heaving airfoils.展开更多
Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verifi...Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verified the performance of the optimized airfoil.Using CRA09-A as the baseline rotor airfoil,the CRA09-B optimized rotor airfoil was designed successfully.Combined with the foundation of high-precision rotor airfoil stationary test technology,the CRA09-B and CRA09-A rotor airfoils were tested in the S3 MA high-speed wind tunnel of ONERA.In order to correct the aerodynamic data,a single parameter linear wall pressure method is used to consider the tunnel effects.The results indicate that multi-objective and multi-constraint optimization design method developed in this study is reliable,and that CRA09-B optimized airfoil provides better stationary performance than CRA09-A airfoil in terms of maximum lift coefficient and lift-to-drag ratio.展开更多
基金supported by the National Key R&D Program of China(No.2024YFC3015804)the Basic Science Center Program for“Space Robot Intelligent Manipulation”,China(No.T2388101)。
文摘Although the thin and cold Martian atmosphere provides the feasibility of rotorcraft flight on Mars,rotors designed for denser Earth atmosphere with small angles of attack hardly generate enough thrust for rotorcraft flight at conventional rotational speeds in the Martian atmosphere.In this paper,we employ the Particle Swarm Optimization(PSO)algorithm to search for the control points of the Bezier curve,completing the parameterization of the airfoil upper and lower curves based on these control points.In order to directly enhance the lift-to-drag ratio of the airfoil at high angles of attack,the NSGA-II algorithm is utilized to optimize the lift-to-drag ratio of NACA 6904 at a=17.5°,Ma=0.43,Re=7600,and CLF 5605 at a=15°,Ma=0.7,Re=7481,respectively.The two-dimensional RANS(Reynolds Average NavierStokes)and k-ωSST turbulence models are employed in the optimization process by CFD to predict the lift and drag characteristics of the airfoil in a Martian environment.Under simulated Mars atmospheric conditions(pressure of 1380 Pa,test temperature of 24°C,equivalent Mars atmospheric density at the surface of 0.0162 g/cm~3),the airfoil after optimized is subjected to rotor lift-drag characteristic tests where a single-rotor lift-drag characteristic test bench is employed for verification.The experimental results demonstrate that the RB-TB-II blade,which is obtained by optimizing the airfoil based on the RB-SWQ-I blade,exhibits a 19.6%increase in Power Loading(PL)and a 20.4%increase in Figure of Merit(FM)compared with the RB-SWQ-I blade.Based on the results of airfoil optimization,increasing the camber at the leading edge of the airfoil under high angles of attack contributes to an improved lift-to-drag ratio.
基金the Scientific Research Projects Unit of Erciyes University under contract no:FDS-2022-11532 and FOA-2025-14773.
文摘This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.
基金funded by Programfor Scientific Research Start-up Funds of Guangdong Ocean University,grant number 060302072101Zhanjiang Marine Youth Talent Project Comparative Study and Optimization of Horizontal Lifting of Subsea Pipeline,grant number 2021E5011.
文摘Airfoil structures play a crucial role across numerous scientific and technological disciplines,with the transition to turbulence and stall onset remaining key challenges in aerodynamic research.While experimental techniques often surpass numerical simulations in accuracy,they still present notable limitations.This paper begins by elucidating the fundamental principles of transition,dynamic stall,and airfoil behavior.It then provides a systematic reviewof six major experimentalmethodologies and examines the emerging role of artificial intelligence in this domain.By identifying key challenges and limitations,the study proposes strategic advancements to address these issues,offering a foundational framework to guide future research in airfoil structures and related fields.
基金funded by University of Guanajuato through Project Convocatoria Institucional de Investigacion Cientifica 2025,161/2025.
文摘This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared with a conventional pin fin heat sink with a circular profile.This study searched for the best thermo-hydraulic performance by translational and rotational positioning of the fins.It is worth mentioning that this work was carried out in two stages.In the first stage,the thermo-hydraulic behavior of the heat sink was studied moving the location of the upper array above the X-axis from to 2.25 mm and above the Y-axis from to 1.275 mm.The second stage examined-2.25-1.55the effects of fin rotation considering the results found in stage 1.However,in this second stage,both arrays were free to rotate.For the upper array,the rotation range was-25°to 25° and for the lower array the rotation range was-15° to 15°.It is worth mentioning that both stages were analyzed for a single Reynolds(Re)number value of 13,000.The optimization results using the multi-objective evolutionary algorithm showed that compared to a NACA 0040 heat sink with fixed,unrotated original configuration(C0),the NACA 0040 heat sink with any Position Configuration(PC)did not significantly improve the heat transfer.Then,the results found in the second stage showed that the effect of the rotation of both sets did not influence the increase in pressure drop.However,it was found that with the Optimal Position and Rotation Configuration(PRCoptimal),which is the optimized array from Stage 1(position)then optimized by rotation,there is a slightly higher Performance Evaluation Criterion(PEC)compared to the original C0 configuration by 7%.Finally,the proposed NACA 0040 heat sink with the optimal rotation and position setting(PRCoptimal)was found to have a PEC of 9%compared to a conventional pin fin heat sink.
基金supported by the National Natural Science Foundation of China(No.52306058)the Natural Science Foundation of Tianjin Municipal Science and Technology Commission,China(No.22JCQNJC00050)。
文摘Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its effectiveness and mechanism in delaying airfoil stall are investigated by numerical simulations.The herringbone groove array is placed on the airfoil's upper surface near the trailing edge,and the effects of groove depth and yaw angle on the control effect are investigated.The results demonstrate that different designs of herringbone groove array can effectively broaden the stable operating range of the airfoil,and the application of herringbone groove array with a depth of only 0.00135 times the chord length and a yaw angle of 45°can result in a28.57%increase in the stable operating range.The flow details indicate that a pair of induced vortices with the same strength and opposite direction are formed near the converging line under the combined action of the accumulation effect of small-scale vortices in the grooves and the spanwise migration flow above the grooves.The induced vortices increase the mixing between the main flow and the boundary layer,allowing the boundary layer to gain sufficient energy to withstand the adverse pressure gradient at high angles of attack,effectively delaying airfoil stall.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23A2069,12372288,12388101,and 92152301)Jilin Province Science and Technology Development Program,China(Grant No.20220301013GX)Aeronautical Science Foundation of China(Grant No.2020Z006058002)。
文摘Recent advances in contrastive language-image pretraining(CLIP)models and generative AI have demonstrated significant capabilities in cross-modal understanding and content generation.Based on these developments,this study introduces a novel framework for airfoil design via natural language interfaces.To the authors’knowledge,this study establishes the first end-to-end,bidirectional mapping between textual descriptions(e.g.,“low-drag supercritical wing for transonic conditions”)and parametric airfoil geometries represented by class-shape transformation parameters.The proposed approach integrates a CLIP-inspired architecture that aligns text embeddings with airfoil parameter spaces through contrastive learning,along with a semantically conditioned decoder that produces physically plausible airfoil geometries from latent representations.The experimental results validate the framework’s ability to generate aerodynamically plausible airfoils from natural language specifications and to classify airfoils accurately based on given textual labels.This research reduces the expertise threshold for preliminary airfoil design and highlights the potential for human-AI collaboration in aerospace engineering.
基金supported by the Japan Society for the Promotion of Science and Grants-in-Aid for Scientific Research(Grant Nos.JP21K14064 and JP23K13239).
文摘Generative adversarial network(GAN)models are widely used in mechanical designs.The aim in the airfoil shape design is to obtain shapes that exhibits the required aerodynamic performance,and conditional GAN is used for that aim.However,the output of GAN contains uncertainties.Additionally,the uncertainties of labels have not been quantified.This paper proposes an uncertainty quantification method to estimate the uncertainty of labels using Monte Carlo dropout.In addition,an uncertainty reduction method is proposed based on imbalanced training.The proposed method was evaluated for the airfoil generation task.The results indicated that the uncertainty was appropriately quantified and successfully reduced.
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.
基金supported by the National Natural Science Foundation of China(Nos.51605200,52206045)。
文摘To reduce the complexity of mixing systems and improve mixing efficiency,this paper proposes a valveless piezoelectric pump integrated with airfoil baffles,which embodies both active and passive mixing attributes.The airfoil baffles are designed using the asymmetric NACA63-412 profile.The impact of the airfoil angle of attack on the flow field within the tube and the output and mixing performance of the piezoelectric pump is investigated.Computational simulations of the tube with airfoil baffle indicated that as the angle of attack increases,the position of vortex generation at the leading and trailing edge regions of the airfoil baffle progressively moves forward in the direction of fluid flow.Then the vortex volume enlarges,and the vortex intensity within the flow field rises.Subsequently,the prototypes of valveless piezoelectric pumps at four different angles of attack are fabricated and their output performances are experimentally evaluated.The results demonstrate that the maximum output flow rate of the pump decreases with an increasing angle of attack.At an angle of attack of 0°,the maximum output flow rate of the pump reaches 225.3 ml/min.Mixing performance experiments are conducted using the piezoelectric pump for the synthesis of Fe_(3)O_(4)particles.The findings indicate that as the angle of attack increases,the number of Fe_(3)O_(4)particles formed in the mixture significantly rises,with a narrower particle size distribution and more regular morphology.At an angle of attack of 15°,the synthesized Fe_(3)O_(4)particles have an approximate diameter of 10μm.The outcomes of this paper offer valuable insights for the design of microfluidic systems,catering to the demands of material synthesis,chemistry,and biomedical applications.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,the Fundamental Research Funds for the Central Universities(No.ILA220101A23)CARDC Fundamental and Frontier Technology Research Fund(No.PJD20200210)the Aeronautical Science Foundation of China(No.20200023052002).
文摘Under complex flight conditions,such as obstacle avoidance and extreme sea state,wing-in-ground(WIG)effect aircraft need to ascend to higher altitudes,resulting in the disappearance of the ground effect.A design of high-speed WIG airfoil considering non-ground effect is carried out by a novel two-step inverse airfoil design method that combines conditional generative adversarial network(CGAN)and artificial neural network(ANN).The CGAN model is employed to generate a variety of airfoil designs that satisfy the desired lift-drag ratios in both ground effect and non-ground effect conditions.Subsequently,the ANN model is utilized to forecast aerodynamic parameters of the generated airfoils.The results indicate that the CGAN model contributes to a high accuracy rate for airfoil design and enables the creation of novel airfoil designs.Furthermore,it demonstrates high accuracy in predicting aerodynamic parameters of these airfoils due to the ANN model.This method eliminates the necessity for numerical simulations and experimental testing through the design procedure,showcasing notable efficiency.The analysis of airfoils generated by the CGAN model shows that airfoils exhibiting high lift-drag ratios under both flight conditions typically have cambers of among[0.08c,0.105c],with the positions of maximum camber occurring among[0.35c,0.5c]of the chord length,and the leading-edge radiuses of these airfoils primarily cluster among[0.008c,0.025c]
基金National Natural Science Foundation of China(Grant Nos.52376202)。
文摘The aerodynamic performance of wind turbine needs to be improved day by day.In this paper,the bionic airfoil of wind turbine and the traditional airfoil are combined to optimize the aerodynamic performance.The new airfoil is synthesized by the method of the mean camber line superposition thickness synthesis.The flow field characteristics of 4 synthetic airfoils were calculated by using the numerical simulation of CFD commercial software Fluent,and compared with 3 original airfoils,new airfoils of different shapes were obtained,and an incomplete synthetic parameterization method for airfoils optimization was proved,which has certain engineering practical value.
文摘This article deals with an experimental study on the aerodynamic characteristics of a low-drag high-speed nature laminar flow (NLF) airfoil for business airplanes in the TST27 wind tunnel at Delft University of Technology, the Netherlands. In this experiment, in an attempt to reduce the errors of measurement and improve its accuracy in high-speed flight, some nonintrusive meas- urement techniques, such as the quantitative infrared thermography (IRT), the digital particle imaging velocimetry (PIV), and the s...
基金National Natural Science Foundation of China (10377015)
文摘A transonic airfoil designed by means of classical point-optimization may result in its dramatically inferior performance under off-design conditions. To overcome this shortcoming, robust design is proposed to find out the optimal profile of an airfoil to maintain its performance in an uncertain environment. The robust airfoil optimization is aimed to minimize mean values and variances of drag coefficients while satisfying the lift and thickness constraints over a range of Mach numbers. A multi-objective estimation of distribution algorithm is applied to the robust airfoil optimization on the base of the RAE2822 benchmark airfoil. The shape of the airfoil is obtained through superposing ten Hick-Henne shape functions upon the benchmark airfoil. A set of design points is selected according to a uniform design table for aerodynamic evaluation. A Kriging model of drag coefficient is constructed with those points to reduce computing costs. Over the Mach range from 0.7 to 0.8, the airfoil generated by the robust optimization has a configuration characterized by supercritical airfoil with low drag coefficients. The small fluctuation in its drag coefficients means that the performance of the robust airfoil is insensitive to variation of Mach number.
文摘For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective.
文摘To avoid the aerodynamic performance loss of airfoil at non-design state which often appears in single point design optimization, and to improve the adaptability to the uncertain factors in actual flight environment, a two-dimensional stochastic airfoil optimization design method based on neural networks is presented. To provide highly efficient and credible analysis, four BP neural networks are built as surrogate models to predict the airfoil aerodynamic coefficients and geometry parameter. These networks are combined with the probability density function obeying normal distribution and the genetic algorithm, thus forming an optimization design method. Using the method, for GA（W）-2 airfoil, a stochastic optimization is implemented in a two-dimensional flight area about Mach number and angle of attack. Compared with original airfoil and single point optimization design airfoil, results show that the two-dimensional stochastic method can improve the performance in a specific flight area, and increase the airfoil adaptability to the stochastic changes of multiple flight parameters.
文摘In this paper, the effects of icing on an NACA 23012 airfoil have been studied. Exper- iments were applied on the clean airfoil, runback ice, horn ice, and spanwise ridge ice at a Reynolds number of 0.6 x 10^6 over angles of attack from -8° to 20% and then results are compared. Gener- ally, it is found that ice accretion on the airfoil can contribute to formation of a flow separation bubble on the upper surface downstream from the leading edge. In addition, it is made clear that spanwise ridge ice provides the greatest negative effect on the aerodynamic performance of the airfoil. In this case, the stall angle drops about 10^6 and the maximum lift coefficient reduces about 50% which is hazardous for an airplane. While horn ice leads to a stall angle drop of about 4°and a maximum lift coefficient reduction to 21%, runback ice has the least effect on the flow pattern around the airfoil and the aerodynamic coefficients so as the stall angle decreases 2% and the maximum lift reduces about 8%.
文摘Abstract A transonic, high Reynolds number natural laminar flow airfoil is designed and studied. The γ-θ transition model is combined with the shear stress transport （SST） k-w turbulence model to predict the transition region for a laminar-turbulent boundary layer. The non-uniform free-form deformation （NFFD） method based on the non-uniform rational B-spline （NURBS） basis function is introduced to the airfoil parameterization. The non-dominated sorting genetic algorithm-II （NSGA-II） is used as the search algo- rithm, and the surrogate model based on the Kriging models is introduced to improve the efficiency of the optimization system. The optimization system is set up based on the above technologies, and the robust design about the uncertainty of the Mach number is carried out for NASA0412 airfoil. The optimized airfoil is analyzed and compared with the original airfoil. The results show that natural laminar flow can be achieved on a supercritical airfoil to improve the aerodynamic characteristic of airfoils.
基金supported by the National Key Project of China(No.GJXM92579)National Natural Science Foundation of China(Nos.92052203,11872230 and 91852108)。
文摘Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element airfoil.Dual-objective optimization is carried out with critical hornshaped ice accumulated during the holding phase.The optimization results show that the present optimization method significantly enhances the iced-state and clean-state performance.The optimal multi-element airfoil has a larger deflection angle and wider gap at the slat and the flap compared with the baseline configuration.The sensitivity of each design parameter is analyzed,which verifies the robustness of the design.The design is further assessed when ice is accreted during the approach and landing phases,which also shows performance improvement.
基金supported by Maric Curie actions EST project FLUBIO(Grant:MEST-CT-2005-020228)support of the HPC-Europa++ project(Project number:211437)support of the European Community-Research Infrastructure Action of the FP7
文摘In the present work,a parametric numerical study is conducted in order to assess the effect of airfoil cambering on the aerodynamic performance of rigid heaving airfoils.The incompressible Navier-Stokes equations are solved in their velocity-pressure formulation using a second-order accurate in space and time finite-difference scheme.To tackle the problem of moving boundaries,the governing equations are solved on overlapping structured grids.The numerical simulations are performed at a Reynolds number of Re=1100 and at different values of Strouhal number and reduced frequency.The results obtained show that the airfoil cambering geometric parameter has a strong influence on the average lift coefficient,while it has a smaller impact on the average thrust coefficient and propulsive efficiency of heaving airfoils.
基金supported by the National Natural Science Foundation of China(No.11902335)。
文摘Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verified the performance of the optimized airfoil.Using CRA09-A as the baseline rotor airfoil,the CRA09-B optimized rotor airfoil was designed successfully.Combined with the foundation of high-precision rotor airfoil stationary test technology,the CRA09-B and CRA09-A rotor airfoils were tested in the S3 MA high-speed wind tunnel of ONERA.In order to correct the aerodynamic data,a single parameter linear wall pressure method is used to consider the tunnel effects.The results indicate that multi-objective and multi-constraint optimization design method developed in this study is reliable,and that CRA09-B optimized airfoil provides better stationary performance than CRA09-A airfoil in terms of maximum lift coefficient and lift-to-drag ratio.
