scholarly journals Numerical studies on aerodynamics of high-speed railway train subjected to strong crosswind

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988727
Author(s):  
Xu Wang ◽  
Yuanhao Qian ◽  
Zengshun Chen ◽  
Xiao Zhou ◽  
Huaqiang Li ◽  
...  
Keyword(s):  
Wind Speed ◽  
High Speed ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Force Coefficient ◽  
Rolling Moment ◽  
Side Force ◽  
Train Speed ◽  
Yaw Angle

Under the action of strong crosswind, the aerodynamic behavior of a rail vehicle at high speed will be changed significantly, which could directly affect the safe operation of the vehicle. With the help of the shape of train used in China, the aerodynamic characteristics of trains with scale of 1:1 is investigated using computational fluid dynamics numerical simulation method, which consists of the variation of aerodynamics force and moment with wind yaw angle, wind speed, train speed, and nose shape. After an initial validation against Baker’s results from wind tunnel test, the numerical model is then used to investigate the aerodynamic characteristics of the trains. The numerical results indicate that lift coefficient of the M train is slightly higher than TMC1 and TMC2 trains. Regardless of aerodynamics force coefficients, TMC1 reaches the maximum at a yaw angle of 75°. Aerodynamics force coefficient increases with both wind speed and train speed, but the change of which is not linear. Comparing aerodynamic force with different geometric dimensions of train nose, it is shown that height–width ratio is insensitive to side force and rolling moment, but sensitive to lift force from the yaw angle 0°–90°. The side force coefficient, as we most concern, is less than other results, when the length–width ratio is 1 and height–width is 0.87.

The Analysis of Aerodynamic Characteristics of the High-Speed Train in Different Railway Conditions under Crosswinds

2013 ◽  
Vol 774-776 ◽  
pp. 58-63
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
Numerical Calculation ◽  
Wind Speed ◽  
Traffic Safety ◽  
Linear Relation ◽  
High Speed ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Transverse Loads ◽  
Train Speed ◽  
Calculation Models

The numerical calculation models of the high-speed train in the straight and different radius curve railway are established. Author calculated transverse forces (moments) acting on the three sections (first train, middle train and rear train). At the same time, under with the shelter wind wall and without the wall, the change trends of side forces coefficients and rolling moments coefficients of trains with the train speed and the transverse wind speed are analyzed. Results show that, in the straight railway and curve railway, transverse loads coefficients increase with the increase of the transverse wind speed and decrease with the increase of the train speed. The transverse forces (moments) of the three sections of the train with the shelter wind wall are opposite to that without the wall. Traffic safety under crosswinds focuses on the rear train with the shelter wind wall and focuses on the first train without the wall. At the same train speed and transverse wind speed, side forces and rolling moments of trains in curve railway is greater than that of trains in straight railway. Absolute values of transverse loads coefficients decreased gradually with the increase of the radius of the curve, and their relationship basically is the linear relation.

scholarly journals The Influence of Ship Rolling Motion on Take-Off Aerodynamic Characteristics of Aircraft

2018 ◽  
Vol 25 (s2) ◽  
pp. 23-29
Author(s):  
He Zheng ◽  
Sun Xiao-yu ◽  
Gu Xuan
Keyword(s):  
Meshless Method ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Ship Motion ◽  
Maximum Speed ◽  
Rolling Motion ◽  
Pitching Moment ◽  
Rolling Moment ◽  
Side Force ◽  
Ship Rolling

Abstract Ship motion is an important factor affecting on the safety of ski-jump take-off. The simplified frigate ship SFS1 was numerically simulated, and the results were compared with the experimental data, the feasibility of the calculation method was verified; Meshless method and WALE turbulence model were used to simulate the process of aircraft ski-jump take-off, aerodynamic characteristics under different rolling conditions during the aircraft ski-jump take-off process were presented. The results showed that: the influence of ship rolling motion on lift coefficient, drag coefficient and pitching moment was small, side force and rolling moment were greatly affected by rolling motion; the region of downwash with the maximum speed was about 10 m from the bow; the safety of ski-jump take-off was greatly affected when aircraft was close to the bow within 20 m.

Experimental Research on Conductor's Ice Accretion and Aerodynamic Characteristics

2014 ◽  
Vol 889-890 ◽  
pp. 497-500
Author(s):  
Han Jie Huang ◽  
Xin Min Li
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Wind Speed ◽  
Experimental Research ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Ice Thickness ◽  
Sudden Increase ◽  
Ice Accretion ◽  
Power Project

For conductor commonly used in power project, research was conducted on its ice accretion and aerodynamic characteristics. Ice mass and ice shape were examined under various icing condition: time, temperature and wind speed. Ice mass increases linearly with time, while the growth rate varies significantly with wind speed. Ice mass does not increase with the fall of temperature; it reaches the max value in a relatively high temperature range of-5°C~-10°C. Ice shape and ice thickness are both important factors that determine conductors aerodynamic characteristics. Sudden increase of lift coefficient may happen at low attack angle for conductor with thick crescent ice shape.

scholarly journals Research on the forward flight performance of rotor based on variable-droop leading edge

2021 ◽  
Vol 39 (3) ◽  
pp. 668-674
Author(s):  
Congcong Li ◽  
Yongjie SHI ◽  
Guohua Xu ◽  
Xingliang Liu
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Integral Form ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Control Effect ◽  
Forward Flight ◽  
Force Coefficient

Aiming at the dynamic stall phenomenon of the retreating side of the rotor in forward flight, the existing flow control method of dynamic leading edge droop was applied to the flow control of forward-flying rotor at three-dimensional scale. A numerical simulation method based on variable droop leading edge is established in this paper. The seesaw rotor is taken as the research object, the moving overset mesh method and RBF grid deformation technology are used, the integral form of Reynolds average N-S equation is the main control equation. The influence of the dynamic leading edge at r/R=0.75~1 on the aerodynamic characteristics of the rotor when the forward ratio is 0.3 is investigated. It is found that variable droop leading edge on the retreating side can effectively inhibit the generation and development of separation vortices near the trailing edge, and has a significant effect on lifting lift coefficient and section normal force coefficient, reducing torque coefficient, and thus improving the equivalent lift-drag ratio of the rotor. In a certain range, the control effect is better with the increase of the droop amplitude under the leading edge.

scholarly journals Influence of Rectangular Strips’ Size on Aerodynamic Performance of a High-Speed Train Subjected to Crosswind

2021 ◽  
Author(s):  
Mengying Wang ◽  
Zhenxu Sun ◽  
Shengjun Ju ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Orthogonal Experimental Design ◽  
High Speed Train ◽  
Force Coefficient ◽  
Roll Moment ◽  
Side Force ◽  
Moment Coefficient ◽  
Side Force Coefficient

Abstract Conventional studies usually assume that the train surface is smooth, so as to simplify the numerical calculation. In fact, the surface of the train is irregular, which will change the flow characteristics in the boundary layer and further affect the aerodynamic performance of a train. In this work, roughness is applied to the roof of a 1:25 scaled train model in the form of longitudinal strips. Firstly, the improved delayed detached eddy simulation (IDDES) method is adopted to simulate the aerodynamic performance of the train model with both smooth and rough surface, which are subjected to crosswind. Results show that the side force coefficient and the roll moment coefficient subjected to rough model decreased by 3.71% and 10.56% compared with the smooth model. Then, the width, height and length of the strips are selected as variables to design different numerical simulation schemes based on the orthogonal experimental design method. Through variance analysis, it can be found that four design parameters have no significant effect on the side force coefficient. Meanwhile, for the roll moment coefficient, the length of the strips in the straight region of the train has a significant effect and the width of the strips has a highly significant effect on it. These conclusions can provide a theoretical basis to improve the aerodynamic performance of the high-speed train subjected to crosswind.

Numerical investigation of hydrodynamic forces acting on the non-stepped and double-stepped planing hulls during yawed steady motion

2018 ◽  
Vol 233 (2) ◽  
pp. 428-442 ◽  
Author(s):  
Parviz Ghadimi ◽  
Saeid Panahi
Keyword(s):  
Steady Motion ◽  
Hydrodynamic Forces ◽  
Maximum Pressure ◽  
Force Coefficient ◽  
Rolling Moment ◽  
Ansys Cfx ◽  
Significant Difference ◽  
Pressure Area ◽  
Comparison Of The Results ◽  
Yaw Angle

This article focuses on the steady motion of yawed planing hulls with emphasis on the effects of adding steps to the bottom of these vessels on the hydrodynamic forces and moments acting on the boat. To analyze the problem, the Ansys-CFX software is used and three different planing hulls are investigated in steady yawed condition. The main targeted results include hydrodynamic forces and moments acting on the boat at different yaw angles and beam Froude numbers which provide important insights regarding the effects of loading and adding step on these forces and moments. The numerically predicted sway forces are compared against experimental data, suggesting that the current numerical model predicts sway and surge forces with reasonable accuracy. Moreover, it is observed that surge force coefficient of the investigated prismatic planing hull with light loading condition does not change significantly when the hull is relocated in a yaw angle, while it is remarkably affected when the boat is heavy. Furthermore, it is observed that this prismatic planing hull has smaller rolling moment in a steady yawed motion, when it moves at larger beam Froude number. Meanwhile, the computed yawing moments of this hull indicate that an increase in speed does not change this moment notably, while an increase in its weight yields larger yawing moment. Comparison of the results of stepped and non-stepped planing hulls indicates that surge force coefficient of the stepped hull is larger, while its sway force and rolling moment are smaller. This is mainly caused by the shape of the interrupted wetted surface and larger number of maximum pressure area in the stepped planing hull. Finally, it is concluded that there is no significant difference between the yawing moment of the investigated stepped and non-stepped planing hulls.

High-Speed Passenger and Intercity Train Aerodynamic Computer Modeling

2000 ◽  
Author(s):  
Samuel Holmes ◽  
Martin Schroeder ◽  
Elton Toma
Keyword(s):  
United States ◽  
Wind Speed ◽  
Computational Fluid Dynamic ◽  
High Speed ◽  
Fluid Dynamic ◽  
The United States ◽  
Motion Simulation ◽  
High Speed Train ◽  
Aerodynamic Loads ◽  
Train Speed

Abstract With the onset of high-speed passenger train service in the United States, the Federal Railroad Administration (FRA) and railroad agencies are concerned with the aerodynamic effects these trains will have on lightweight freight equipment, such as empty double stack container cars. This paper presents the results of a research project that evaluated this interaction. In this study we conducted a series of computational fluid dynamic (CDF) calculations to characterize the aerodynamic loads on a container consist passed by a high-speed train. A train motion simulation program was used to determine resultant motion and risk of overturning or derailment of the container consist. Numerous cases were studied in which train speed and wind speed and direction were varied.

A numerical study of aerodynamic characteristics of a high-speed train with different rail models under crosswind

2020 ◽  
pp. 095440972096925
Author(s):  
Zhiwei Jiang ◽  
Tanghong Liu ◽  
Houyu Gu ◽  
Zijian Guo
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Significant Difference ◽  
Aerodynamic Performances ◽  
Yaw Angle

The CFD (Computational Fluid Dynamics) numerical simulation method with the DES (detached eddy simulation) approach was adopted in this paper to investigate and compare the aerodynamic performance, pressure distributions of the train surface, and flow fields near the train model placed above the subgrade with non-rail, realistic rail, and simplified rail models under crosswind. The numerical methods were verified with the wind tunnel tests. Significant differences in aerodynamic performances of the train body and bogie were found in the cases with and without a rail model as the presence of the rail model had significant impacts on the flow field underneath the vehicle. A larger yaw angle can result in a more significant difference in aerodynamic coefficients. The deviations of the train aerodynamic forces and the pressure distribution on the train body with the realistic and simplified rail models were not significant. It was concluded that a rail model is necessary to get more realistic results, especially for large yaw angle conditions. Moreover, a simplified rectangular rail model is suggested to be employed instead of the realistic rail and is capable to get accurate results.

A study on the aerodynamic characteristics of a stratospheric airship in its entire flight envelope

2017 ◽  
Vol 232 (5) ◽  
pp. 902-921 ◽  
Author(s):  
Xiao-Ying Sun ◽  
Tian-E Li ◽  
Guo-Chang Lin ◽  
Yue Wu
Keyword(s):  
Pitch Angle ◽  
Aerodynamic Characteristics ◽  
Wind Pressure ◽  
Scale Model ◽  
Aerodynamic Forces ◽  
Rolling Moment ◽  
Pressure Drag ◽  
Stratospheric Airship ◽  
Flight Envelope ◽  
Yaw Angle

Aerodynamic characteristics of a stratospheric airship in its entire flight envelope, including take-off, ascending, cruising, descending, and landing, is an important part of its research topic. In this paper, experiments of wind pressure measurement on a 1/30-scale stratospheric airship model were carried out to obtain a better assessment of the aerodynamic characteristics during the cruising process. Based on the wind pressure distribution, the effects of pitch angle, yaw angle, and combined angles (pitch angle and yaw angle acted simultaneously) on the aerodynamics of the airship were analyzed. In addition, the contributions of different portions of the airship hull (namely head, middle, and tail) to the aerodynamic forces and moments were discussed. The experimental results imply that the tail portion is the main contributor to pressure drag force. The combined angles significantly increase aerodynamic forces and rolling moment, and the rolling moment produced by the middle portion accounts for the major proportion. Secondly, the computational fluid dynamics method was verified and employed to study the aerodynamic characteristics of the full-scale model in its entire flight envelope based on the decision of the wind environment parameters and attitude. As a main result, it can be concluded that, more attention should be paid to the airship when it is located in the troposphere and near the ground with an inclined take-off angle.

Experimental Study on the Influence Factors of Static Aerodynamic Characteristics of Ice-Coated Commonly Used Conductors

2013 ◽  
Vol 774-776 ◽  
pp. 1227-1231
Author(s):  
Han Jie Huang ◽  
Xin Min Li
Keyword(s):  
Wind Speed ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Influence Factors ◽  
Aerodynamic Characteristics ◽  
Ice Thickness ◽  
Aerodynamic Load ◽  
Coated Conductor ◽  
Sudden Increase ◽  
Aerodynamic Coefficients

For conductors commonly used in the high and ultra-high voltage transmission projects, research was conducted on how ice shape, ice thickness, wind speed and angle of attack affect the static aerodynamic characteristics of ice-coated conductor. The ice shape and the shape of ice-coated conductor are both important factors that determine the aerodynamic characteristics of conductor. Sudden increase of lift coefficient may happen at low angle of attack. Wind speed shows less effect on aerodynamic characteristics of ice-coated conductor with streamlined shape than that of conductor with blunt shape. Under most attack angles, aerodynamic coefficients increase as the ice thickness increases. The aerodynamic load on ice-coated conductor does not increase linearly with the diameter of conductor.

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