Based on ullstability of inversion algorithms of the lidar equation caused by molecular scattering,a new algorithm to derive both the aerosol extinction to backscatter ratio and the extinchon coefficient profile is pr...Based on ullstability of inversion algorithms of the lidar equation caused by molecular scattering,a new algorithm to derive both the aerosol extinction to backscatter ratio and the extinchon coefficient profile is proposed in this paper.As shown in numerical experiments,in case of a ground-based lidar,the error in the aerosol optical depth solution can be less than 10%,and the error of < 6.7 in the aerosol exhnction to backscatter ratio can be obtained if the error in the lidar constant is<6%;and in the case of a spaceborne lidar,the present method can be ugh to determine the lidar constant at a short wavelength with an accuracy of being better than 1%.展开更多
To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃...To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃induced vibration response data of a three⁃span four⁃row double⁃layer cable PV support system.The wind⁃induced vibration characteristics with different PV module tilt angles,wind speeds,and wind direction angles were analyzed.The results showed that the double⁃layer cable large⁃span flexible PV support can effectively control the wind⁃induced vibration response and prevent the occur⁃rence of flutter under strong wind conditions.The maxi⁃mum value of the wind⁃induced vibration displacement of the flexible PV support system occurs in the windward first row.The upstream module has a significant shading effect on the downstream module,with a maximum effect of 23%.The most unfavorable wind direction angles of the structure are 0°and 180°.The change of the wind direction angle in the range of 0°to 30°has little effect on the wind vi⁃bration response.The change in the tilt angle of the PV modules has a greater impact on the wind vibration in the downwind direction and a smaller impact in the upwind di⁃rection.Special attention should be paid to the structural wind⁃resistant design of such systems in the upwind side span.展开更多
Aero engines are key power components that provide thrust for the aircraft.The cerme turbine disc allows the new-generation domestic fighter aircraft to increase the overall thrust of the aero engine.Quantifying coati...Aero engines are key power components that provide thrust for the aircraft.The cerme turbine disc allows the new-generation domestic fighter aircraft to increase the overall thrust of the aero engine.Quantifying coatings and analyzing the stress on the teeth play critical roles in improving the turbine disc’s performance,which are two issues must be solved urgently.First,this work pro poses a quantitative analysis algorithm to conduct the Three-Dimensional(3D)distribution informa tion mining of the extracted coatings.Then,it proposes an Industrial Computed Laminography(ICL)reconstruction algorithm for non-destructively reconstructing the turbine disc’s high-quality3D morphological actual feature.Finally,a Finite Element Analysis(FEA)under the ultimate thrus is conducted on ICL reconstruction to verify the working status of the new-generation aero-engine turbine disc.The results show that the proposed quantitative analysis algorithm digitizes the aggre gated conditions of the coating with a statistically normalized Z_(1)value of–2.15 and a confidence leve higher than 95%.Three image-quality quantitative indicators:Peak Signal-to-Noise Ratio(PSNR)Structural Similarity Index Measure(SSIM),and Normalized Mean Square Distance(NMSD)of the proposed ICL reconstruction algorithm on turbine disc laminographic image are 26.45,0.88,and 0.73respectively,which are better than other algorithms.The mechanical analysis of ICL more realisti cally reflects the stress and deformation than that of 3D modeling.This work provides new ideas for the iterative research of new-generation aero-engine turbine discs.展开更多
This paper aims to tackle the calculation efficiency problem raised in the cavitation-flow simulation of the aviation centrifugal pump due to the fading-away interface resulting from the dissipation of numerics used i...This paper aims to tackle the calculation efficiency problem raised in the cavitation-flow simulation of the aviation centrifugal pump due to the fading-away interface resulting from the dissipation of numerics used in the phase-change control equation for unstructured-grid multiphase flow,and due to the limitation of flow time-step in whole flow regimes,the control equation of vapor–liquid two-phase flow considering cavitation mass transport is established firstly,modifying the momentum equation by introducing the surface tension,and adding the artificial convective flow to the phase equation to solve the numerical dissipation problem.Secondly,in consideration of the local time step principle and based on the multi-dimensional general limiter algorithm with explicit solutions under the OpenFOAM platform,a solution method of steady-state VOF (Volume of Fluid) model considering cavitation two-phase change is constructed,and the feasibility of this method is verified by NACA hydrofoil and NASA flat plate inducer.Finally,based on the platform developed,the cavitation performance of an aviation centrifugal pump inducer is analyzed.The research results show that the error of the calculated cavitation pressure distribution for NACA hydrofoil between the simulation test and the experimental-test is less than 5%,and the maximum error of calculated cavitation number at pump head dropping for NASA high-speed flat plate inducer between the simulation test and the experimental-test is 2.1%.The cavitation area observed in the simulation test is the same as that obtained in the high-speed photography test.Based on the OpenFOAM simulation method,the position of pump head dropping of the fuel centrifugal pump can be accurately captured.The error of the calculated cavitation number at pump head dropping between the simulation test and the experimental test is about 3.7%,showing high calculation accuracy.展开更多
A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simu...A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simulate the incompressible flow field.The sound field is predicted by discretizing acoustic perturbation equations(APEs)with dispersionrelation-preserving space scheme and low-dispersion and low-dissipation Runge-Kutta time integration.A sharp-interface IBM based on ghost-cell is implemented for present two-step DNS-APE approach to deal with complex moving bodies with Cartesian grids.The present method is validated through simulations of sound generation caused by flow past a rotating cylinder,an oscillating cylinder,and tandem oscillating and stationary cylinders.The sound generated by typical kinds of complicated bio-inspired locomotions,i.e.,flapping flight by wings of varied shapes and collective undulatory swimming in tandem,are investigated using present method.The results demonstrate potential of the hybrid approach in addressing flowinduced sound generation and propagation with complex moving boundaries in a fluid medium,especially for the sound characteristics of bio-mimetic flows,which might shed lights on investigations on bio-acoustics,ethology of complex animal system,and related bio-mimetic design for quietness.展开更多
The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor...The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.展开更多
文摘Based on ullstability of inversion algorithms of the lidar equation caused by molecular scattering,a new algorithm to derive both the aerosol extinction to backscatter ratio and the extinchon coefficient profile is proposed in this paper.As shown in numerical experiments,in case of a ground-based lidar,the error in the aerosol optical depth solution can be less than 10%,and the error of < 6.7 in the aerosol exhnction to backscatter ratio can be obtained if the error in the lidar constant is<6%;and in the case of a spaceborne lidar,the present method can be ugh to determine the lidar constant at a short wavelength with an accuracy of being better than 1%.
基金The National Natural Science Foundation of China(No.52338011).
文摘To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃induced vibration response data of a three⁃span four⁃row double⁃layer cable PV support system.The wind⁃induced vibration characteristics with different PV module tilt angles,wind speeds,and wind direction angles were analyzed.The results showed that the double⁃layer cable large⁃span flexible PV support can effectively control the wind⁃induced vibration response and prevent the occur⁃rence of flutter under strong wind conditions.The maxi⁃mum value of the wind⁃induced vibration displacement of the flexible PV support system occurs in the windward first row.The upstream module has a significant shading effect on the downstream module,with a maximum effect of 23%.The most unfavorable wind direction angles of the structure are 0°and 180°.The change of the wind direction angle in the range of 0°to 30°has little effect on the wind vi⁃bration response.The change in the tilt angle of the PV modules has a greater impact on the wind vibration in the downwind direction and a smaller impact in the upwind di⁃rection.Special attention should be paid to the structural wind⁃resistant design of such systems in the upwind side span.
基金supported by the National Natural Science Foundation of China(No.51975026)。
文摘Aero engines are key power components that provide thrust for the aircraft.The cerme turbine disc allows the new-generation domestic fighter aircraft to increase the overall thrust of the aero engine.Quantifying coatings and analyzing the stress on the teeth play critical roles in improving the turbine disc’s performance,which are two issues must be solved urgently.First,this work pro poses a quantitative analysis algorithm to conduct the Three-Dimensional(3D)distribution informa tion mining of the extracted coatings.Then,it proposes an Industrial Computed Laminography(ICL)reconstruction algorithm for non-destructively reconstructing the turbine disc’s high-quality3D morphological actual feature.Finally,a Finite Element Analysis(FEA)under the ultimate thrus is conducted on ICL reconstruction to verify the working status of the new-generation aero-engine turbine disc.The results show that the proposed quantitative analysis algorithm digitizes the aggre gated conditions of the coating with a statistically normalized Z_(1)value of–2.15 and a confidence leve higher than 95%.Three image-quality quantitative indicators:Peak Signal-to-Noise Ratio(PSNR)Structural Similarity Index Measure(SSIM),and Normalized Mean Square Distance(NMSD)of the proposed ICL reconstruction algorithm on turbine disc laminographic image are 26.45,0.88,and 0.73respectively,which are better than other algorithms.The mechanical analysis of ICL more realisti cally reflects the stress and deformation than that of 3D modeling.This work provides new ideas for the iterative research of new-generation aero-engine turbine discs.
基金supported by the National Science and Technology Major Project, China (No. J2019-V-0016-0111)the Aviation Engine and Gas Turbine Basic Science Center Project, China (No. P2022-B-V-003-001)+3 种基金the Defense Industrial Technology Development Program, China (No. JCKY2022607C002)the AECC Industry University Cooperation Project, China (No. HFZL2022CXY013)the National Natural Science Foundation of China (No. 52372396)the Key R&D Project in Shaanxi Province, China (No. 2021GXLH-01-16)。
文摘This paper aims to tackle the calculation efficiency problem raised in the cavitation-flow simulation of the aviation centrifugal pump due to the fading-away interface resulting from the dissipation of numerics used in the phase-change control equation for unstructured-grid multiphase flow,and due to the limitation of flow time-step in whole flow regimes,the control equation of vapor–liquid two-phase flow considering cavitation mass transport is established firstly,modifying the momentum equation by introducing the surface tension,and adding the artificial convective flow to the phase equation to solve the numerical dissipation problem.Secondly,in consideration of the local time step principle and based on the multi-dimensional general limiter algorithm with explicit solutions under the OpenFOAM platform,a solution method of steady-state VOF (Volume of Fluid) model considering cavitation two-phase change is constructed,and the feasibility of this method is verified by NACA hydrofoil and NASA flat plate inducer.Finally,based on the platform developed,the cavitation performance of an aviation centrifugal pump inducer is analyzed.The research results show that the error of the calculated cavitation pressure distribution for NACA hydrofoil between the simulation test and the experimental-test is less than 5%,and the maximum error of calculated cavitation number at pump head dropping for NASA high-speed flat plate inducer between the simulation test and the experimental-test is 2.1%.The cavitation area observed in the simulation test is the same as that obtained in the high-speed photography test.Based on the OpenFOAM simulation method,the position of pump head dropping of the fuel centrifugal pump can be accurately captured.The error of the calculated cavitation number at pump head dropping between the simulation test and the experimental test is about 3.7%,showing high calculation accuracy.
基金supported by the National Natural Science Foundation of China(Grant Nos.52301380 and 11602277).
文摘A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simulate the incompressible flow field.The sound field is predicted by discretizing acoustic perturbation equations(APEs)with dispersionrelation-preserving space scheme and low-dispersion and low-dissipation Runge-Kutta time integration.A sharp-interface IBM based on ghost-cell is implemented for present two-step DNS-APE approach to deal with complex moving bodies with Cartesian grids.The present method is validated through simulations of sound generation caused by flow past a rotating cylinder,an oscillating cylinder,and tandem oscillating and stationary cylinders.The sound generated by typical kinds of complicated bio-inspired locomotions,i.e.,flapping flight by wings of varied shapes and collective undulatory swimming in tandem,are investigated using present method.The results demonstrate potential of the hybrid approach in addressing flowinduced sound generation and propagation with complex moving boundaries in a fluid medium,especially for the sound characteristics of bio-mimetic flows,which might shed lights on investigations on bio-acoustics,ethology of complex animal system,and related bio-mimetic design for quietness.
文摘The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.
