Effect of wind gusts on the dynamics of railway vehicles running on a curved track

2017 ◽  
Vol 232 (4) ◽  
pp. 1103-1120 ◽  
Author(s):  
Wonhee You ◽  
Hyukbin Kwon ◽  
Joonhyuk Park ◽  
Yujeong Shin
Keyword(s):  
Dynamic Characteristics ◽  
Wind Tunnel Test ◽  
Simulation Software ◽  
Scale Model ◽  
Railway Vehicle ◽  
Wind Gust ◽  
Railway Vehicles ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Curved Track

Due to global warming, there is an increasing number of wind gusts that affect the stability of railway vehicles. A railway vehicle running on a curved track during a wind gust is subjected to multiple forces simultaneously, which include the centrifugal force and forces exerted by the wind gust and cant, and they significantly affect the vehicle’s dynamic characteristics as well as its safety. The forces increase the vibration of carbodies and the risk of derailment and overturning of cars; the effect is worse on irregular tracks. In order to review the phenomenon in detail, a 1/20 scale model of a railway vehicle was built to measure the aerodynamic coefficients in five directions—side force, lift force, roll moment, pitch moment, and yaw moment—through a wind tunnel test. The data collected were applied as external forces to a full-scale railway vehicle model traveling on a curved track. Using a multibody simulation software program, SIMPACK, a railway vehicle was modeled, which was then used in the simulation of the dynamic characteristics and safety of vehicles while traveling on a curved track during a wind gust. Using the actual measured track data from the curved zone, a comparison was made on the dynamic characteristics of the car traveling, with and without a wind gust, on a curved track with a railway curve radius of 599 m; also, the difference was analyzed with the direction of the wind gust blowing from inside and toward the center of curvature. The results showed that in the presence of a wind gust blowing from outside the curvature with an average speed of 25 m/s it is advisable to stop train services on grounds of safety.

scholarly journals Hunting Stability of High-Speed Railway Vehicles Under Steady Aerodynamic Loads

2018 ◽  
Vol 18 (07) ◽  
pp. 1850093 ◽  
Author(s):  
Xiao-Hui Zeng ◽  
Jiang Lai ◽  
Han Wu
Keyword(s):  
Stability Analysis ◽  
High Speed ◽  
Critical Speed ◽  
Railway Vehicle ◽  
Aerodynamic Load ◽  
High Speed Railway ◽  
Aerodynamic Loads ◽  
Railway Vehicles ◽  
Pitch Moment ◽  
Hunting Stability

With the rising speed of high-speed trains, the aerodynamic loads become more significant and their influences on the hunting stability of railway vehicles deserve to be considered. Such an effect cannot be properly considered by the conventional model of hunting stability analysis. To this end, the linear hunting stability of high-speed railway vehicles running on tangent tracks is studied. A model considering the steady aerodynamic loads due to the joint action of the airflow facing the moving train and the crosswind, is proposed for the hunting stability analysis of a railway vehicle with 17 degrees of freedom (DOF). The key factors considered include: variations of the wheel–rail normal forces, creep coefficients, gravitational stiffness and angular stiffness due to the actions of the aerodynamic load, which affects the characteristics of hunting stability. Using the computer program developed, numerical calculations were carried out for studying the behavior of the linear hunting stability of vehicles under steady aerodynamic loads. The results show that the aerodynamic loads have an obvious effect on the linear critical speeds and instability modes. The linear critical speed decreases monotonously as the crosswind velocity increases, and the influences of pitch moment and lift force on the linear critical speed are larger than the other components of the aerodynamic loads.

scholarly journals An Investigation into the Modeling Methodology of the Coil Spring

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Liangcheng Dai ◽  
Maoru Chi ◽  
Hongxing Gao ◽  
Jianfeng Sun
Keyword(s):  
Mass Distribution ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Railway Vehicle ◽  
Spring Model ◽  
Coil Spring ◽  
Railway Vehicles ◽  
Equivalent Models ◽  
Laboratory Test Results ◽  
Exciting Frequency

The coil spring is an important element in the suspension system of railway vehicles, and its structural vibration caused by the mass distribution can deteriorate the dynamic performance of the vehicle. However, the coil spring is usually modelled as a simple linear force element without considering the dynamic characteristics in multibody dynamic simulations of railway vehicles. To integrate the dynamic characteristics of the coil spring into the simulation, three equivalent dynamic models of the coil spring are established by treating the coil spring as multimass spring series, Timoshenko beam, and flexible spring, respectively. The frequency-sweep method is applied to obtain the dynamic response of the proposed models of coil spring, and the accuracy of the models’ results has been compared and verified by the laboratory test. Results show that all of these three equivalent models can reflect the influence of the spring mass distribution on its dynamic responses. Compared with the mass-spring series and beam element equivalent models, the flexible spring model can better reflect the dynamic stiffness and stress of the coil spring changing with the exciting frequency. Thus, the flexible spring model proposed in this paper is more applicable to railway vehicle system dynamics and the fatigue analysis.

Detached-Eddy Simulations of the Effects of Different Wind Gust Models on the Unsteady Aerodynamics of Road Vehicles

2010 ◽  
Author(s):  
Tristan Favre ◽  
Gunilla Efraimsson
Keyword(s):  
Unsteady Aerodynamics ◽  
Vertical Direction ◽  
Wind Gust ◽  
Deterministic Models ◽  
Aerodynamic Loads ◽  
Simulation Techniques ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Vehicle Shape ◽  
Yaw Angle

The relative flexibility of nowadays simulation techniques offers an alternative way to experiments in order to investigate unsteady crosswind aerodynamics in an industrial framework. In this study, time-accurate simulations, Detached-Eddy Simulations (DES), are used to simulate the flow around a simple vehicle shape, the so-called Windsor model. The ReL of the corresponding flow case is 2.0 · 106. The influence of different deterministic models of wind gusts on the aerodynamic loads and moments are studied. The wind gusts are varied in the stream-wise and the vertical direction. The magnitude of the gusts models corresponds to a yaw angle of 20°. The aerodynamic loads calculated show a large excess of drag coupled with a reduction of the pitch moment. In addition, although the side force has a smooth variation in the gust, overshoots up to 18% higher than the steady value of yaw moment are also observed.

Adaptive Mechatronic Suspension of Railway Vehicles: Focus on Lateral Dynamics

2003 ◽  
Author(s):  
Włodzimierz Choroman´ski ◽  
Jerzy Kisilowski
Keyword(s):  
Computer Control ◽  
Control Unit ◽  
Railway Vehicle ◽  
Fuzzy Controllers ◽  
Railway Vehicles ◽  
Lateral Dynamics ◽  
Suspension Parameters ◽  
The Subject ◽  
Curved Track ◽  
Classic Solution

The subject of research in this work are models of railway bogies with so-called mechatronic suspension. The author presents concepts of the railway bogies construction in which the suspension parameters are controlled electronically by a computer control unit. The main purpose of the control is to stabilise the motion of the railway vehicle on the straight track and to ensure good guiding features on curved track. In the case of the classic solution for railway bogies a simultaneous fulfilment of both requirements imposes a contradictory requirement on the suspension parameters. It seems that a mechatronic suspension which has adaptively changeable parameters can overcome these difficulties. The authors propose fuzzy controllers to the synthesis of the control unit.

scholarly journals Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision

Machines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 91
Author(s):  
Sunghyun Lim ◽  
Yong-hyeon Ji ◽  
Yeong-il Park
Keyword(s):  
Reaction Force ◽  
Crash Test ◽  
Railway Vehicle ◽  
Buffer System ◽  
Railway Vehicles ◽  
Hydraulic Shock Absorber ◽  
Coupling Buffer ◽  
Absorption Performance ◽  
Different Characteristics ◽  
The Impact

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.

scholarly journals Investigation of the Time Dependence of Wind-Induced Aeroelastic Response on a Scale Model of a High-Rise Building

2021 ◽  
Vol 11 (8) ◽  
pp. 3315
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Time Dependence ◽  
Wind Tunnel Test ◽  
Structural Response ◽  
Cumulative Distribution ◽  
Scale Model ◽  
Acquisition Time ◽  
Test Results ◽  
High Rise ◽  
High Rise Building

Experimental wind tunnel test results are affected by acquisition times because extreme pressure peak statistics depend on the length of acquisition records. This is also true for dynamic tests on aeroelastic models where the structural response of the scale model is affected by aerodynamic damping and by random vortex shedding. This paper investigates the acquisition time dependence of linear transformation through singular value decomposition (SVD) and its correlation with floor accelerometric signals acquired during wind tunnel aeroelastic testing of a scale model high-rise building. Particular attention was given to the variability of eigenvectors, singular values and the correlation coefficient for two wind angles and thirteen different wind velocities. The cumulative distribution function of empirical magnitudes was fitted with numerical cumulative density function (CDF). Kolmogorov–Smirnov test results are also discussed.

Simulation and Simulation Software Development of the Braking Process of a Subway Train

2014 ◽  
Vol 556-562 ◽  
pp. 294-301 ◽  
Author(s):  
Long Han ◽  
Chun Tian ◽  
Yan Wang ◽  
Meng Ling Wu ◽  
Zhuo Jun Luo
Keyword(s):  
Computational Effort ◽  
Simulation Software ◽  
System Model ◽  
Brake System ◽  
Railway Vehicle ◽  
Model Parameters ◽  
Modeling Process ◽  
Time Simulation ◽  
Subway Train ◽  
Braking Process

This paper deals with the problem of braking process modeling. A subway train braking process simulation software is built, which composes of a GUI and a underlying model. The underlying model consists of a train model and a brake system model. The train model is simplified and built by assembling subcomponent element models of a railway vehicle. The brake system model is simplified and built based on experimental data in order to reduce computational effort. The GUI of the software can be use to input model parameters, display simulation results, and store simulation data. As a result of the simplifications of the modeling process, the developed software can perform real time simulation.

On the Planning and Construction of Railway Curved Track

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Sono Bhardawaj ◽  
Rakesh Chandmal Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
High Speed ◽  
Time Derivative ◽  
Railway Track ◽  
Lateral Acceleration ◽  
Transition Curve ◽  
Railway Vehicle ◽  
Geometric Conditions ◽  
Curve Track ◽  
Curved Track ◽  
Transition Curves

Increasing demand for railway vehicle speed has pushed the railway track designers to develop high-quality track. An important measure of track quality is the character of the transition curve track connecting different intersecting straight tracks. A good transition curve track must be able to negotiate the intermittent stresses and dynamic effects caused by changes in lateral acceleration at high speed. This paper presents the constructional methods for planning transition curves considering the dynamics of movement. These methods consider the non-compensated lateral acceleration, deviation in lateral acceleration and its higher time derivatives. This paper discusses the laying methods of circular, vertical and transition curves. Key aspects in laying a curved track e.g. widening of gauge on curves are discussed in this paper. This paper also suggests a transition curve which is effective not only from a dynamic point of view considering lateral acceleration and its higher time derivative but also consider the geometric conditions along with the required deflection angle.

scholarly journals Aerodynamic characteristics of detachable fairing shells in a subsonic incompressible flow

2019 ◽  
Author(s):  
Yu.V. Grebeneva ◽  
A.Yu. Lutsenko ◽  
A.V. Nazarova
Keyword(s):  
Flow Simulation ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Stream Velocity ◽  
Normal Forces ◽  
Pitch Moment ◽  
Lift Off ◽  
Windward Surface ◽  
Aerodynamic Quality

The purpose of the work was to mathematically simulate the flow around the fairing shell of the launch vehicle at a low subsonic free-stream velocity in the α = 0...360° angle-of-attack range. The calculations were performed using the SolidWorks Flow Simulation software package and the open source OpenFoam package based on the use of numerical methods for simulating the motion of liquid and gas. Within the research, we obtained the flow patterns and the aerodynamic coefficients of the longitudinal and normal forces, the pitch moment, and calculated the aerodynamic quality of the shell. Furthermore, we determined the positions of the stable equilibrium of the model and revealed the features of the flowing around the shell of the combined form at flow from the convex and concave sides. Next, we analyzed the leeward lift-off zones and the zones with increased pressure on the windward surface during flow from the concave side. Finally, we compared the obtained characteristics with the experimental data of TsAGI.

scholarly journals Wind Gust Measuring at Low Altitude Using An Unmanned Aerial System

2021 ◽  
Author(s):  
Alton Yeung
Keyword(s):  
Turbulence Models ◽  
Satellite System ◽  
Data System ◽  
Measurement Unit ◽  
Wind Gust ◽  
Wind Gusts ◽  
Low Altitude ◽  
And Performance ◽  
Global Navigation Satellite ◽  
Aerial Platform

A small unmanned aerial vehicle (UAV) was developed with the specific objective to explore atmospheric wind gusts at low altitudes within the atmospheric boundary layer (ABL). These gusts have major impacts on the flight characteristics and performance of modern small unmanned aerial vehicles. Hence, this project was set to investigate the power spectral density of gusts observed at low altitudes by measuring the gusts with an aerial platform. The small UAV carried an air-data system including a fivehole probe that was adapted for this specific application. The air-data system measured the local wind gusts with an accuracy of 0.5 m/s by combining inputs from a five-hole probe, an inertial measurement unit, and Global Navigation Satellite System (GNSS) receivers. Over 20 flights were performed during the development of the aerial platform. Airborne experiments were performed to collect gust data at low altitudes between 50 m and 100 m. The result was processed into turbulence spectrum and the measurements were compared with the MIL-HDBK-1797 von K´arm´an turbulence model and the results have shown the model underpredicted the gust intensities experienced by the flight vehicle. The anisotropic properties of low-altitude turbulence were also observed when analyzing the measured gusts spectra. The wind and gust data collected are useful for verifying the existing turbulence models for low-altitude flights and benefit the future development of small UAVs in windy environment.

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