Characteristics Of High-speed Train Research Articles

Aerodynamics of High-Speed Trains with Respect to Ground Simulation

Wind tunnel testing is commonly used to assess and optimize the aerodynamic characteristics of high-speed trains. The train model is usually mounted above a static ground plane, but a moving ground is necessary for the correct representation of the relative motion between train and ground. This study focuses on the effect of the applied ground simulation on the aerodynamics of a high-speed train. Wind tunnel tests using a stationary and a moving ground were carried out using a 1:20 scale model of a high-speed train’s first car. Numerical simulations for two moving ground configurations are created, and the simulation setup is validated using surface pressure measurements from the wind tunnel tests. It is shown that the ground simulation has a significant effect on the drag in the considered yaw angle range. Additionally, the change in drag due to bogie fairings is evaluated and an impact of the applied ground simulation on the drag reduction is observed. The drag reduction of front and rear bogie fairings is valued similarly using a static ground, however on a moving ground the drag reduction of front bogie fairings is significantly increased. Good agreement between simulations and experiments is achieved.

Experimental Study of Effects of the Third Medium on the Maximum Friction Coefficient between Wheel and Rail for High-Speed Trains

The changes of the friction coefficient between wheel and rail affect the wheel-rail adhesion characteristics of high-speed trains. The adhesion state in the wheel-rail contact area could be distinguished by the maximum friction coefficient between wheel and rail. The wheel-rail adhesion is of great significance for high-speed train traction. In order to study the influence of water, oil, fallen leaves, quartz sand, or their mixtures on the maximum friction coefficient between high-speed wheel and rail, a wheel-rail contact test bed is built to carry out the wheel-rail contact test and wheel-rail friction contact test. The comparative analysis of the test results shows that the axle load has little influence on the maximum friction coefficient between wheel and rail. Water, oil, and fallen leaves would reduce the maximum friction coefficient. Quartz sand could increase the maximum friction coefficient in a short time, while the excessive static friction coefficient would damage the wheel and rail. Besides, the maximum friction coefficient of water, oil, and fallen leaves mixing in pairs is lower than each of them existing alone. Both water and oil could increase the adhesion of quartz sand, and the effect of water is better. Therefore, when the sand still could not meet enough traction, it could be considered to add some water to increase the wheel-rail adhesion.

Multimode Intelligent Control Based on Multidata Fusion Filtering in High-Speed Train Traffic Signal and Control

As the speed of high-speed trains continues to increase, the intelligent monitoring of high-speed trains has become a concern of people. This research mainly discusses the application of multimode intelligent control of multidata fusion filtering in high-speed train traffic signal and control. In multimodal intelligent control, BangBang, PI control, adaptive fuzzy PID control, and expert monitoring control under special circumstances can be used, respectively, according to the error and the rate of change of the error, which can achieve the best control effect under safe conditions. Take the allowable speed of ATP as the target speed of the control system, and combine the operation process, operation requirements, traction characteristics, braking characteristics of high-speed trains, and meet the two conditions for improving the operating efficiency of high-speed trains. According to the dynamic expected speed value of high-speed trains, dynamically adjust the switching threshold. This study uses a pulse signal generator to simulate the speed data of the vehicle speed sensor (all pulse data), and then read the speed (pulse) signal data through the pulse signal acquisition card, and display the simulated speed data under the Kingview software. The monitoring computer is used to collect train speed information, display speed information, manage speed information, and output speed information. Then, through OPC technology, the simulation speed data is transmitted to MATLAB software for multidata fusion filtering processing and multimodal control simulation. In the simulation process, the train adopts a multimodal intelligent control response scheme, with a total time of 2183.7 s, which is shortened by 214.5 s and improved by nearly 10%. The multimode intelligent control scheme of multidata fusion filtering proposed in this study can better meet the control of high-speed train traffic signals.

Study on Traction Rod Load Characteristics of High Speed Train

Study on Traction Rod Load Characteristics of High Speed Train

Influence of Typical Subgrade Structures on Aerodynamic Characteristics of High Speed Trains in Cross wind Conditions

Influence of Typical Subgrade Structures on Aerodynamic Characteristics of High Speed Trains in Cross wind Conditions

Numerical Investigation of Aerodynamic Characteristics of High Speed Train

In this work, initially the effect of nose shape on the drag characteristics of a high speed train is studied. Then the influence of cross winds on the aerodynamics and hence the stability of such modern high speed trains is analyzed. CFD analysis was conducted using STAR-CCM+ on trains with different features and important aerodynamic coefficients such as the drag, side force and rolling moment coefficients have been calculated for yaw angles of crosswinds ranging from 0° to 90°. The results show that the modification on train nose shape can reduce the drag up to more than 50%. It was also found that, bogie faring only reduces small percentage of drag but significantly contributed to higher rolling moment and side force coefficient hence induced train instability.

Influence of pantograph fixing position on aerodynamic characteristics of high-speed trains

To study the influence of the pantograph fixing position on aerodynamic characteristics of high-speed trains, the aerodynamic models of high-speed trains with eight cars were established based on the theory of computational fluid dynamics, and eight cases with pantographs fixed on different positions and in different operational orientations were considered. The pantographs were fixed on the front or the rear end of the first middle car or fixed on the front or the rear end of the last middle car. The external flow fields of the high-speed trains were numerically simulated using the software STAR-CCM+. The results show that the pantograph fixing position has little effect on the aerodynamic drag force of the head car and has a large effect on the aerodynamic drag force of the tail car. The influences of the pantograph fixing position on the aerodynamic lift forces of the head car, tail car and pantographs are obvious. Among the eight cases, considering the total aerodynamic drag force of the train and the aerodynamic lift force of the lifted pantograph, when the pantographs are fixed on the rear end of the last middle car and the lifted pantograph is in the knuckle-upstream orientation, the aerodynamic performance of the high-speed train is the best.

Aerodynamic characteristics of high speed train under turbulent cross winds: A numerical investigation using unsteady-RANS method

Increasing velocity combined with reduced mass of modern high speed trains poses the question of influence of strong cross winds on its aerodynamics. Strong cross winds may affect the running stability of high speed trains via the amplified aerodynamic forces and moments. In this study, simulations of turbulent cross wind flows over the leading and end car of ICE-2 high speed train have been performed at different yaw angles The train aerodynamic problems are closely associated with the flows occurring around train. The flow around the train has been considered as incompressible and was obtained by solving the incompressible form of the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations combined with the realizable k-epsilon turbulence model. Important aerodynamic coefficients such as the side force and rolling moment coefficients have been calculated for yaw angles ranging from -30° to 60° and compared to results obtained from wind tunnel tests. The dependence of the flow structure on yaw angle has also been presented.

Hunting Stability Test for Railway Vehicles by Hardware-In-the-Loop Simulation with Actual Yaw Damper (Development and Qualitative Verification of Test Equipment)

Hunting stability is one of the most essential characteristics of high speed trains, and it has been investigated by roller rig testing at a testing bench and numerical simulation. Those ways have their own drawbacks in their accuracy, cost and flexibility. We propose a new approach, Hardware-In-the-Loop Simulation (HILS), to test hunting stability of railway vehicles. HILS is a kind of simulation that uses some actual devices, and it enables us to increase simulation accuracy, keeping its cost-effectiveness and flexibility high. In this paper, we demonstrated hunting stability tests by HILS, which showed that the tests worked properly. Furthermore, we also exhibited how excitation device responsiveness affects quantitative analysis of hunting stability through simulation studies.

Research on Two Ends Energy-Absorbing Structure of High-Speed Railway Passenger Car Body

Based on characteristics of high-speed trains, a special passive protective structure was designed and simulated by the non-linear FEA code LS-DYNA. The two-step energy-absorbing structure fixed on the cab side and the similar function structure on the other end were studied. It was proved that the two-step structure deformed orderly and had an energy absorbing capacity of 3.4MJ which could protect the cab effectively and that the rear end low stiffness zone had an energy absorbing capacity of 6.5MJ which also could protect the integrity of the passenger areas. Three typical train-to-train collision scenarios were studied by full-scale FEA method.