scholarly journals Aerodynamic coefficients of railway vehicles in cross-wind – introduction and preliminary research

2019 ◽  
Vol 2019 (6) ◽  
pp. 11-20
Author(s):  
Piotr Lalewicz ◽  
Danuta Bryja
Keyword(s):  
High Speed ◽  
Railway Vehicle ◽  
Wind Tunnel Testing ◽  
Aerodynamic Coefficients ◽  
Railway Vehicles ◽  
Train Speed ◽  
Preliminary Research ◽  
Cfd Method ◽  
Wind Stability ◽  
Dynamics Method

In recent years, dynamic development of high-speed railways is observed in Europe and in the world. Due to the train speeds increase, aerodynamics of railway vehicles becomes more and more important issue. In the paper, the cross-wind stability problem of a railway vehicle and the influence of the train speed on this phenomenon is discussed. As a derailment risk analysis requires to determine in total six cross-wind aerodynamic forces and moments acting on a given vehicle, a knowledge of six associated with them aerodynamic coefficients is a groundwork for train stability analysis. Two most common methods of analysis of air flow around trains are pointed out – wind tunnel testing and CFD method (Computational Fluid Dynamics method). Both methods are described in the paper, in reference to PN-EN 14067-6:2018-10 and TSI requirements, and later a CFD method is applied to examine a basic train model. The main aim of this preliminary research was to recognize CFD method as a tool for a further research on cross-wind-induced vibrations of a train - bridge system.

Model Predictive Control Application to Flexible-Bodied Railway Vehicles for Vibration Suppression

2013 ◽  
Vol 10 ◽  
pp. 25-35
Author(s):  
P.E. Orukpe
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
High Speed ◽  
Ride Comfort ◽  
The Body ◽  
Ride Quality ◽  
Linear Matrix ◽  
Railway Vehicle ◽  
Railway Vehicles ◽  
Effective Manner

In this paper, we apply model predictive control (MPC) based on mixed H2/H to active vibration control of the flexibility of railway vehicle to improve ride quality. However, the flexibility in the body of high-speed railway vehicles creates difficulties which in practice may result in the body structure being heavier than what it is supposed to be. The use of active suspension helps to model the vehicle and its flexibility in an effective manner. Conventional control approaches are compared with linear matrix inequality MPC technique using flexible-bodied railway vehicle as an example. The result indicates that the MPC technique performs better in improving ride comfort compared to the passive and classical techniques when flexible modes are present.

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 Research and Analysis of Permanent Magnet Transmission System Controls on Diesel Railway Vehicles

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 173
Author(s):  
Lili Kang ◽  
Dongjie Jiang ◽  
Chaoying Xia ◽  
Yongjiu Xu ◽  
Kaiyi Sun
Keyword(s):  
Permanent Magnet ◽  
Control Strategy ◽  
High Speed ◽  
Control Strategies ◽  
Transmission System ◽  
Torque Control ◽  
Railway Vehicle ◽  
Transmission Systems ◽  
Traction Motor ◽  
Railway Vehicles

As the energy crisis and environmental pollution continue to be a gradual threat, the energy saving of transmission systems has become the focus of railway vehicle research and design. Due to their high-power density and efficiency features, permanent magnet synchronous motors (PMSM) have been gradually applied in railway vehicles. To improve the efficiency of the transmission system of diesel railway vehicles, it is a good option to use PMSM as both a generator and traction motor to construct a full permanent magnet transmission system (FPMTS). Due to the application of the new FPMTS, some of the original control strategies for diesel railway vehicle transmission systems are no longer applicable. Therefore, it is necessary to adjust and improve the control strategies to meet the needs of FPMTS. We studied several key issues that affect the reliability and comfort of the vehicles. As such, this paper introduced the FPMTS control strategy, including the coordinated control strategy of the diesel and the traction motor, the two degrees of freedom (2DOF) decoupling current regulator, the maximum torque control of the standardized unit current, the wheel slip protection control, and the fault protection strategy. The experiment was carried out on the test platform and the test run of the diesel shunting locomotive equipped with the FPMTS. The results showed that the control strategy described in this paper met the operation characteristics of the FPMTS and that the control performance was superior. The study of FPMTS lays the foundation for the subsequent application of permanent magnet motors in high-powered diesel locomotives and high-speed diesel multi-units.

Full-Scale Crash Testing Facilities for a Railway Vehicle

2012 ◽  
Author(s):  
Jin Sung Kim ◽  
Hyun Seung Jung ◽  
Tae Soo Kwon ◽  
Won Mok Choi ◽  
Seung Wan Son
Keyword(s):  
High Speed ◽  
Impact Test ◽  
Full Scale ◽  
Displacement Sensor ◽  
Crash Test ◽  
Railway Vehicle ◽  
Single Item ◽  
Railway Vehicles ◽  
Crash Testing ◽  
The Impact

KRRI (Korea Railroad Research Institute) has successfully performed several tens of impact tests of crash parts for a railway vehicles. Full-scale crash testing facilities were newly established including a crash barrier, dynamic load cell, high speed DAS (Data Acquisition System), a laser displacement sensor, dummies, a motor car and etc. This paper introduces series of impact test results using full-scale crash testing facilities. The impact test for railway vehicles consists of three categories, i.e. single item tests, module tests and crash structure tests. For single item tests, expansion tubes, composite tubes, collapsible tubes and etc. were tested. For module tests, a crash test of a light collision safety device with an expansion tube and triggering mechanism was performed. For crash structure tests, several full-scale crash tests were performed including front-end and cab structures with or without dummies. The crash testing equipment developed will be able to evaluate the occupant safety as well as the structural crashworthiness of a train.

Effects of infrastructure on the aerodynamic performance of a high-speed train

2020 ◽  
pp. 095440972095221
Author(s):  
Ming Wang ◽  
Xiao-Zhen Li ◽  
Jun Xiao ◽  
Hai-Qing Sha ◽  
Qi-Yang Zou
Keyword(s):  
High Speed ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
High Speed Train ◽  
Aerodynamic Coefficients ◽  
Pressure Distributions ◽  
Train Speed ◽  
Truss Bridge ◽  
Flat Ground

The aerodynamic characteristics of typical high-speed train can be affected by the operating infrastructure, which will affect the flow structure around train body. Five different infrastructure scenarios, including no infrastructure, flat ground, embankment, viaduct and truss bridge, are systemically studied. The purpose is to examine the uncertainties of aerodynamic coefficients caused by the infrastructure. Attention is drawn to variations of aerodynamic coefficients at certain yaw angles caused by the changes in crosswind and train speed. The middle car is chosen for quantifying the effects of five infrastructures by using wind tunnel test and numerical simulations, then followed by a detailed study on aerodynamic characteristics of three cars of train running on viaduct. Pressure distributions are also drawn for a better interpretation. Result shows that the uncertainties in aerodynamic coefficients becomes more obvious as the infrastructure gets complex and yaw angles get bigger. The aerodynamic coefficients of three cars with the viaduct scenario show the similar uncertainties, which are mostly affected by the change in crosswind rather than the train speed.

Random Vibration Properties of High-Speed Railway Vehicle Considering Random Parameters of Track Structure

2013 ◽  
Vol 321-324 ◽  
pp. 62-66
Author(s):  
Bin Li ◽  
Xue Yi Liu
Keyword(s):  
High Speed ◽  
Random Vibration ◽  
Railway Vehicle ◽  
Random Parameters ◽  
High Speed Railway ◽  
Speed Increase ◽  
Vibration Properties ◽  
Track System ◽  
Vibration Responses ◽  
Train Speed

Applied theory of vehicle/track coupled dynamic, random vibration properties of high-speed railway vehicles are researched in random parameters of fastener and ballast stiffness obeyed normal distribution and track irregularity combined the sample of artificial shortwave and the sample of low disturbance irregularity of high-speed railway in German with train speed increase. The results show that dynamic interaction of vehicle/track system and vibration responses of railway vehicle are increased with train speed increase, but the increase of wheel-set acceleration is much more. The parameters of high speed railway track structure (especially fastener and ballast stiffness) had much more impact to random vibration responses of vehicle/track system, so they should be optimized and remained in a narrow range.

scholarly journals On the Crosswind Stability of High Speed Railway Vehicles

2006 ◽  
Author(s):  
Christian Wetzel ◽  
Carsten Proppe
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Probabilistic Methods ◽  
Railway Vehicle ◽  
Uniform Rule ◽  
High Speed Railway ◽  
Railway Vehicles ◽  
Turbulent Fluctuations ◽  
Crosswind Stability ◽  
The Given

The crosswind stability against overturning is a major design criterium for high speed railway vehicles. Due to the increasing interoperability in Europe it has also become an important international task. In recent years efforts have been made to derive an uniform rule in certifying railway vehicles. In this case especially probabilistic methods have been proposed These probabilistic techniques are common design criteria for wind turbines. A sophisticated method to compute the reliability of railway vehicles under strong crosswind is presented. In consideration of the given gust signal and the high-frequency turbulent fluctuations of the wind the response of a simplified train model is computed. The major failure criterion to determine the reliability is the lowest wheel-rail contact force of the railway vehicle. Special attention is given to the stochastic modeling of the high-frequency turbulent fluctuations of the wind and to the effect of these fluctuations on the crosswind stability.

scholarly journals Development, Modeling and Control of a Dual Tilt-Wing UAV in Vertical Flight

Drones ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 71
Author(s):  
Luz M. Sanchez-Rivera ◽  
Rogelio Lozano ◽  
Alfredo Arias-Montano
Keyword(s):  
Dynamic Model ◽  
Attitude Control ◽  
Test Bench ◽  
Aerodynamic Coefficients ◽  
Nonlinear Dynamic Model ◽  
Modeling And Control ◽  
Drag And Lift ◽  
And Control ◽  
Dynamics Method ◽  
Indoor And Outdoor

Hybrid Unmanned Aerial Vehicles (H-UAVs) are currently a very interesting field of research in the modern scientific community due to their ability to perform Vertical Take-Off and Landing (VTOL) and Conventional Take-Off and Landing (CTOL). This paper focuses on the Dual Tilt-wing UAV, a vehicle capable of performing both flight modes (VTOL and CTOL). The UAV complete dynamic model is obtained using the Newton–Euler formulation, which includes aerodynamic effects, as the drag and lift forces of the wings, which are a function of airstream generated by the rotors, the cruise speed, tilt-wing angle and angle of attack. The airstream velocity generated by the rotors is studied in a test bench. The projected area on the UAV wing that is affected by the airstream generated by the rotors is specified and 3D aerodynamic analysis is performed for this region. In addition, aerodynamic coefficients of the UAV in VTOL mode are calculated by using Computational Fluid Dynamics method (CFD) and are embedded into the nonlinear dynamic model. To validate the complete dynamic model, PD controllers are adopted for altitude and attitude control of the vehicle in VTOL mode, the controllers are simulated and implemented in the vehicle for indoor and outdoor flight experiments.

scholarly journals Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

2021 ◽  
Vol 62 (9) ◽  
Author(s):  
Patrick M. Seltner ◽  
Sebastian Willems ◽  
Ali Gülhan ◽  
Eric C. Stern ◽  
Joseph M. Brock ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Data ◽  
Static Stability ◽  
Free Flight ◽  
Aerodynamic Coefficients ◽  
Flow Topology ◽  
Motion Data ◽  
Continuous Rotation ◽  
German Aerospace

Abstract The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

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