Aerodynamic drag is the dominant factor contributing to energy consumption as the operational speed of high speed trains increases,necessitating effective aerodynamic optimization strategies.This study investigates th...Aerodynamic drag is the dominant factor contributing to energy consumption as the operational speed of high speed trains increases,necessitating effective aerodynamic optimization strategies.This study investigates the aerodynamic characteristics of the bogie region under two bogie fairing configurations:baseline bogie fairing(BBF)and full bogie fairing(FBF).Both stationary and rotating wheelset conditions are considered.Wind tunnel experiments were conducted on a full-scale bogie model equipped with a wheelset drive system to simulate wheelset rotation.Additionally,numerical simulations were employed to analyze flow structures.Results indicate that the FBF configuration promotes a more uniform front-to-rear pressure distribution in the bogie region.The rotation of the wheelset notably affects the airflow near the wheels and extends its influence throughout the entire bogie region.Specifically,wheelset rotation reduces drag by 6.38%in the BBF configuration but increases drag by 3.5%in the FBF configuration.Further analysis reveals that,in the FBF configuration,aerodynamic drag primarily originates from the wheelsets.The rotating wheelset increases the aerodynamic drag by 18.8%for the rear wheelset,which is attributed to the shift in the pressure curve on the wheelset in the rotating direction.Therefore,the impact of wheelset rotation on aerodynamic characteristics should not be overlooked.展开更多
This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity...This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.展开更多
An investigation of the effect of simplifying bogie regions on the aerodynamic performance of a high-speed train was carried out by studying four train models,to explore possible ways to optimise the train underbody s...An investigation of the effect of simplifying bogie regions on the aerodynamic performance of a high-speed train was carried out by studying four train models,to explore possible ways to optimise the train underbody structure,improve the underbody aerodynamic performance,and reduce the aerodynamic drag.The shear stress transport(SST)k-ωturbulence model was used to study the airflow features of the high-speed train with different bogie regions at Re=2.25×10^(6).The calculated aerodynamic drag and surface pressure were compared with the experimental benchmark of wind tunnel tests.The results show that the SST k-ωmodel presents high accuracy in predicting the flow fields around the train,and the numerical results closely agree with the experimental data.Compared with the train with simplified bogies,the aerodynamic drag of the train with a smooth surface and the train with enclosed bogie cavities/inter-carriage gaps decreases by 38.2%and 30.3%,respectively,while it increases by 10.8%for the train with cavities but no bogies.Thus,enclosing bogie cavities shows a good capability of aerodynamic drag reduction for a new generation of highspeed trains.展开更多
This paper investigates the main scale analysis of the aerodynamic noise in the foremost bogie area by the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)analogy.The mechanism of the aerodynamic noise...This paper investigates the main scale analysis of the aerodynamic noise in the foremost bogie area by the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)analogy.The mechanism of the aerodynamic noise in this area has been excavated.The aerodynamic excitation results show that the bogie divides the bogie compartment into two cavities,each of which contains a large circulating flow and presents multi-peak characteristics in the frequency domain.The far-field noise results suggest that in the speed range of 200−350 km/h,the aerodynamic noise mechanism in the bogie area is the same.Cavity noise is the main noise mechanism in the foremost bogie area,and the bogie divides the bogie cabin into two cavities,thereby changing the aerodynamic noise in this area.展开更多
This paper reviews the current status of investigation on snow accumulation on the bogies of high-speed trains(HSTs) running in snowy region. First, the background of the snow issue occurring to the HST and the contra...This paper reviews the current status of investigation on snow accumulation on the bogies of high-speed trains(HSTs) running in snowy region. First, the background of the snow issue occurring to the HST and the contra-measures for the snow issue proposed in the past decades are provided by reviewing previous studies. Next, the methodology for investigating the snow issue developed by High-Speed Train Research Center of Central South University is introduced, including the numerical simulation research platform and the experimental devices for two-phase flow wind tunnel tests. Then, effective anti-snow flow control schemes for guiding the underbody airflow and their impact on the motion and accretion of snow in the installation region of the bogies are presented. Finally, the remaining investigating challenge for the snow issue of HST and the future research with respect to the challenge are provided from an engineering application viewpoint.展开更多
There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of tra...There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of train-track time-variant system is put forward. Each vehicle is modeled as a multi-body system with 26 degrees of freedomand the action of coupler is also considered. The track structure is modeled as an assembly of track elements with 30degrees of freedom, then the spatially coupling vibration matrix equation of the train-track time-variant system is es-tablished on the basis of the principle of total potential energy with stationary value and the "set-in-right-position"rule. The track vertical geometric irregularity is considered as the excitation source of the vertical vibration of thesystem, and the hunting wave of car bogie frame is taken as the excitation source of lateral vibration of the system.The spatially coupling vibration matrix equation of the system is solved by Wilson-θ direct integration method. Theapproximation of the calculated results to the spot test results demonstrates the feasibility and effectiveness of thepresented analysis method. Finally, some other vibration responses of the system are also obtained.展开更多
基金Projects(52322215,U2368213,U24B20119,12202142)supported by the National Natural Science Foundation of China。
文摘Aerodynamic drag is the dominant factor contributing to energy consumption as the operational speed of high speed trains increases,necessitating effective aerodynamic optimization strategies.This study investigates the aerodynamic characteristics of the bogie region under two bogie fairing configurations:baseline bogie fairing(BBF)and full bogie fairing(FBF).Both stationary and rotating wheelset conditions are considered.Wind tunnel experiments were conducted on a full-scale bogie model equipped with a wheelset drive system to simulate wheelset rotation.Additionally,numerical simulations were employed to analyze flow structures.Results indicate that the FBF configuration promotes a more uniform front-to-rear pressure distribution in the bogie region.The rotation of the wheelset notably affects the airflow near the wheels and extends its influence throughout the entire bogie region.Specifically,wheelset rotation reduces drag by 6.38%in the BBF configuration but increases drag by 3.5%in the FBF configuration.Further analysis reveals that,in the FBF configuration,aerodynamic drag primarily originates from the wheelsets.The rotating wheelset increases the aerodynamic drag by 18.8%for the rear wheelset,which is attributed to the shift in the pressure curve on the wheelset in the rotating direction.Therefore,the impact of wheelset rotation on aerodynamic characteristics should not be overlooked.
基金Projects(51875411,52232013)supported by the National Natural Science Foundation of ChinaProject(19DZ2290400)supported by the Shanghai Professional Technical Service Platform Program,China。
文摘This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.
基金Project(2020YFF0304103-03) supported by the National Key Research and Development Program of ChinaProject(2020JJ4737) supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project (202045014) supported by the Central University Financial Funds,ChinaProject(P2019J023) supported by the Science and Technology Research Program of China National Railway Group Co.,Ltd。
文摘An investigation of the effect of simplifying bogie regions on the aerodynamic performance of a high-speed train was carried out by studying four train models,to explore possible ways to optimise the train underbody structure,improve the underbody aerodynamic performance,and reduce the aerodynamic drag.The shear stress transport(SST)k-ωturbulence model was used to study the airflow features of the high-speed train with different bogie regions at Re=2.25×10^(6).The calculated aerodynamic drag and surface pressure were compared with the experimental benchmark of wind tunnel tests.The results show that the SST k-ωmodel presents high accuracy in predicting the flow fields around the train,and the numerical results closely agree with the experimental data.Compared with the train with simplified bogies,the aerodynamic drag of the train with a smooth surface and the train with enclosed bogie cavities/inter-carriage gaps decreases by 38.2%and 30.3%,respectively,while it increases by 10.8%for the train with cavities but no bogies.Thus,enclosing bogie cavities shows a good capability of aerodynamic drag reduction for a new generation of highspeed trains.
基金Project(2017YFB1201103)supported by the National Key Research and Development Plan of ChinaProject(2019zzts540)supported by the Graduate Student Independent Innovation Project of Central South University,China。
文摘This paper investigates the main scale analysis of the aerodynamic noise in the foremost bogie area by the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)analogy.The mechanism of the aerodynamic noise in this area has been excavated.The aerodynamic excitation results show that the bogie divides the bogie compartment into two cavities,each of which contains a large circulating flow and presents multi-peak characteristics in the frequency domain.The far-field noise results suggest that in the speed range of 200−350 km/h,the aerodynamic noise mechanism in the bogie area is the same.Cavity noise is the main noise mechanism in the foremost bogie area,and the bogie divides the bogie cabin into two cavities,thereby changing the aerodynamic noise in this area.
基金Project(2016YFB1200404)supported by the National Key Research and Development Program of ChinaProjects(51605044,U1534210)supported by the National Science Foundation of China。
文摘This paper reviews the current status of investigation on snow accumulation on the bogies of high-speed trains(HSTs) running in snowy region. First, the background of the snow issue occurring to the HST and the contra-measures for the snow issue proposed in the past decades are provided by reviewing previous studies. Next, the methodology for investigating the snow issue developed by High-Speed Train Research Center of Central South University is introduced, including the numerical simulation research platform and the experimental devices for two-phase flow wind tunnel tests. Then, effective anti-snow flow control schemes for guiding the underbody airflow and their impact on the motion and accretion of snow in the installation region of the bogies are presented. Finally, the remaining investigating challenge for the snow issue of HST and the future research with respect to the challenge are provided from an engineering application viewpoint.
基金Project (50078006) supported by the National Natural Science Foundation of China Project (2001G029) supported by the Foundation of the Science and Technology Section of the Railway Bureau
文摘There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of train-track time-variant system is put forward. Each vehicle is modeled as a multi-body system with 26 degrees of freedomand the action of coupler is also considered. The track structure is modeled as an assembly of track elements with 30degrees of freedom, then the spatially coupling vibration matrix equation of the train-track time-variant system is es-tablished on the basis of the principle of total potential energy with stationary value and the "set-in-right-position"rule. The track vertical geometric irregularity is considered as the excitation source of the vertical vibration of thesystem, and the hunting wave of car bogie frame is taken as the excitation source of lateral vibration of the system.The spatially coupling vibration matrix equation of the system is solved by Wilson-θ direct integration method. Theapproximation of the calculated results to the spot test results demonstrates the feasibility and effectiveness of thepresented analysis method. Finally, some other vibration responses of the system are also obtained.
