Performance Of High-speed Train Research Articles

Effect of wing height layout on the aerodynamic performance ofhigh-speed train

Purpose This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof. Design/methodology/approach The improved delayed detached eddy simulation method based on shear stress transport k- ω turbulence model has been used to conduct computational fluid dynamics simulation on the train with three different wing height layouts, at a Reynolds number of 2.8 × 106. The accuracy of the numerical method has been validated by wind tunnel experiments. Findings The wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights. Originality/value This paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.

Enhancement of Aerodynamic Performance of High Speed Train Through Nose Profile Design: A Computational Fluid Dynamics Approach

Aerodynamic drag of fast-moving train has significant impact on its fuel consumption and design safety. To improve aerodynamic performance, the drag forces on the train surfaces must be reduced. Train’s front-end nose design has boundless geometrical variations that can be applied for improved performance. Three geometric characteristics were used in present research: A-pillar roundness, nose length that controls its shrinking, and nose bluntness. Latin-Hypercube based random sampling method was used to determine appropriate values of these parameters for specific range. Using Computational Fluid Dynamics (CFD), a numerical approach was used to analyze train aerodynamic performance based on selected factors and operating conditions. Comparisons based on analysis of the base design and proposed design models were made and evaluated for enhanced performance. CFD analysis of the base design and iterative improvements in modified designs indicate drag reduction through change in A-pillar roundness and bluntness of nose to be 10% and 22%, respectively. The increase in nose length which controls nose shrinkage causes the drag to increase by 35%. Similarly, the boundary layer and pressure distribution on the front end of train were also considered and analyzed for performance improvement. It was concluded that the length controlling nose shrinkage of proposed train design is the key factor among the selected geometric parameters that has more influence on drag on high-speed train surface in comparison to other parameters considered. This research effort offers a modification, analysis and comparison of front-end nose geometry of high-speed train to improve aerodynamic performance and consequently fuel consumption.

Composite Adaptive Anti-Disturbance Fault Tolerant Control of High-Speed Trains With Multiple Disturbances

This article investigates the fault tolerant control problem with anti-disturbance performance of high speed trains (HSTs) with actuator constraints in case of multiple random faults that may occur. By taking multiple disturbances into account, a new multiple point-mass stochastic jump system model of the HST is firstly established to describe the possible multiple faults. Based on the adaptive disturbance observer, a novel composite adaptive anti-disturbance fault tolerant control strategy is proposed to ensure that the velocity and position tracking error system of HSTs is stochastically stable. Moreover, except for the case where the transition probabilities (TPs) of the failure process are completely known, this article also discusses and analyzes the cases where the TPs are partially unknown and completely unknown, respectively. Finally, some examples are given to evaluate the effectiveness of the results.

Optimization on the Crosswind Stability of Trains Using Neural Network Surrogate Model

Under the influence of crosswinds, the running safety of trains will decrease sharply, so it is necessary to optimize the suspension parameters of trains. This paper studies the dynamic performance of high-speed trains under crosswind conditions, and optimizes the running safety of train. A computational fluid dynamics simulation was used to determine the aerodynamic loads and moments experienced by a train. A series of dynamic models of a train, with different dynamic parameters were constructed, and analyzed, with safety metrics for these being determined. Finally, a surrogate model was built and an optimization algorithm was used upon this surrogate model, to find the minimum possible values for: derailment coefficient, vertical wheel-rail contact force, wheel load reduction ratio, wheel lateral force and overturning coefficient. There were 9 design variables, all associated with the dynamic parameters of the bogie. When the train was running with the speed of 350 km/h, under a crosswind speed of 15 m/s, the benchmark dynamic model performed poorly. The derailment coefficient was 1.31. The vertical wheel-rail contact force was 133.30 kN. The wheel load reduction rate was 0.643. The wheel lateral force was 85.67 kN, and the overturning coefficient was 0.425. After optimization, under the same running conditions, the metrics of the train were 0.268, 100.44 kN, 0.474, 34.36 kN, and 0.421, respectively. This paper show that by combining train aerodynamics, vehicle system dynamics and many-objective optimization theory, a train’s stability can be more comprehensively analyzed, with more safety metrics being considered.

Slow feature analysis-aided detection and diagnosis of incipient faults for running gear systems of high-speed trains

Incipient faults in running gear systems corrupt the overall performance of high-speed trains, increasing the necessity of fault detection and diagnosis whose purpose is to maintain the safe and stable operation of high-speed trains. For this purpose, a novel data-driven method, that utilizes Hellinger distance and slow feature analysis, is proposed in this study. By integrating Hellinger distance into slow feature analysis, a new test statistic is defined for detecting incipient faults in running gear systems. Furthermore, the hidden Markov method is developed for performing reliable fault diagnosis tasks. The salient strengths of the proposed method lie in its satisfactory fault detectability on the one hand and the considerable robustness against high-level noises on the other hand. Finally, the effectiveness of the proposed method is verified through a numerical example and a running gear system of high-speed trains under actual working conditions.

Influence of wind barrier on the transient aerodynamic performance of high-speed trains under crosswinds at tunnel–bridge sections

Porous wind barriers (PWBs) are gradually applied to tunnel–bridge–tunnel infrastructures (TBTIs) along high-speed railway lines. Due to the remarkable aerodynamic effect of high-speed trains (HSTs), the windproof performance of a PWB at tunnel–bridge section (TBS) is particularly critical when a HST passes through the TBTI under crosswind. And it seems to be easily ignored by researchers. This study aims to determine the influence mechanism of the PWB in the TBS. A CFD dynamic model of air–train–PWB was built based on porous media theory, and its reliability is verified by model and field tests. The main results are as follows: the corresponding variation amplitudes of the train’s aerodynamic load coefficients are reduced by 36–95% when a PWB is set in the TBS; adopting the same design parameters along the full-length PWB on the TBTI is unreasonable; the PWB height and porosity in the TBS must be increased and reduced more than 33%, respectively, to achieve equivalent windproof performance. The conclusions in this paper can provide a preliminary idea for the optimization design of the PWB on the TBTI.

Relationship between Multi-pier Settlement and Dynamic Performance of High-speed Train

Relationship between Multi-pier Settlement and Dynamic Performance of High-speed Train

Data-driven Detection and Diagnosis of Incipient Faults in Electrical Drives of High-Speed Trains

Incipient faults in electrical drives can corrupt overall performance of high-speed trains; however, they are difficult to discover because of their slight fault symptoms. By sufficiently exploiting the distribution information of incipient faults, this paper presents the reason why incipient faults cannot be detected by the existing fault detection and diagnosis (FDD) methods. Under principal component analysis (PCA) framework, we propose a new data-driven FDD method, which is named probability-relevant PCA (PRPCA), for electrical drives in high-speed trains. The salient strengths of the PRPCA-based FDD method are: 1) it can greatly improve the fault detectability; it is suitable for non-Gaussian electrical drives; 2) based on the improved fault detectability, it can achieve accurate fault diagnosis via support vector machine; and 3) it can be easily applied to electrical drives even if neither physical models or parameters nor expert knowledge of drive systems is given; and it is of highly computational efficiency that can meet requirements on the real-time FDD. A set of experiments on a dSPACE platform-based traction system of the CRH2A-type high-speed train are carried out to demonstrate the effectiveness of the proposed method.

Research on Parameters of the Curve Negotiation Performance of High-Speed Train Composed of Multiple Vehicles

This paper calculates the wheel/rail nonlinear numerical solution that both changes in trend or in values are relatively consistent conclusion, using different methods of comparative analysis of the cycle dynamics system for studying the influence of the curve negotiating velocity and orbital parameters on the performance of high-speed train. Then based on single-section vehicle system program, a high-speed train coupling system considering vehicle terminal connection device is established. The influence of curve negotiating velocity and orbital parameters on the performance of high-speed train is analyzed. The results show that, with the curve negotiating velocity increasing, the derailment coefficient, rate of wheel load reduction, and the vertical force of wheel rail have a tendency to rise after falling first, lateral force of wheel rail monotone increasing. When the vehicle is in a superelevation state, the indicators are slightly lower than the equilibrium state. While the indicators with parameters change significantly when the vehicle is in a underelevation state. For instance, when the radius of the curve is 5000m to the radius 6700m, the derailment coefficient increases by 53.6% and rate of wheel load reduction is increased by 44.1%.

Online condition assessment of high-speed trains based on Bayesian forecasting approach and time series analysis

High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train\'s operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.

Study of the Air Conditioning Installation Mode’s Effect on Aerodynamic Performance of High Speed Train

With the improvement of the train speed, the interaction between train and air increases obviously, creating a series of aerodynamic performance problems that cannot be ignored. This paper focuses on high-speed train drag reduction research, to study whether the installation of air conditioning system will have a greater resistance to the train and the influence of the diversion angle of the air deflector on the aerodynamic characteristics of the train running in different environments. The results indicates as follows: In the open environment, when the roof of the train is installed with air conditioning, the resistance coefficient of the head car, the middle car and the tail car is increased by 27.39%, 20.33% and 18.25% respectively, while the resistance coefficient of the pantograph is reduced by 22.07% and the resistance coefficient of the vehicle up to 19.23%; With the air conditioning shroud diversion angle changed from 90° to 15°, in the open environment, vehicle air resistance decreased by 11.77%, the total resistance of the three air-conditioning decreased by 59.04%; In the crosswind environment, the overturning moment coefficients of air conditioners increased by 14.84%, 17.61% and 4.90% respectively.

Composite Disturbance‐Observer‐Based Control and Control for High Speed Trains with Actuator Faults

AbstractTo guarantee the position and velocity tracking performance of high speed trains (HSTs) with actuator faults, a composite control algorithm consisting of the disturbance‐observer‐based control (DOBC) and control is proposed. Based on the multiple point‐mass model, the dynamics of HSTs is established by a cascade of carriages which are connected by flexible couplers, during the procedure of which, the running resistance, actuator faults and multiple disturbances are taken into account. The multiple disturbances are composed of two parts, one of which is the ramp resistance due to the track slope, the other is unknown gusts which can be modeled as a harmonic disturbance with time‐varying frequency. The unknown gusts is estimated and rejected via the DOBC methodology, meanwhile, the running resistance and the ramp resistance are attenuated by the control methodology. According to the Lyapunov stability analysis and LMI‐based algorithms, main results are derived such that the closed‐loop system is asymptotically stable and the desired performance can be guaranteed. Compared with the numeral simulation results with the single control method, it is demonstrated that the proposed control methodology is more effective and the system has a higher precision of position and velocity tracking.

The Dynamic Behavior of High Speed Train Using Magnetorheological Technology on the Curve Track

The era of high speed railway has come and the most important issue of the high speed train is the safety, which is directly related to billions of families. One of the most serious threats to the safety of the high speed train is the vibration of train body at curve track, which may cause the train off the track. Semi-active vibration control method is a possible solution compared with active control method which has robust problem and passive control method which has efficiency issue. Magnetorheological technology is a typical semi-active vibration control method which has been widely used in the automobile, architectural construction and aerospace. The high speed train using magnetorheological technology has not been fully investigated especially for the dynamic performance at curve track. In this paper, a high-speed train model with MRF dampers is simulated by a combined ADAMS and MATLAB simulation. The dynamic performance of high speed train operating at different speeds and turning radius is investigated to reveal the mechanism of how the MRF damper affects the train’s stability and vibration. The results show that the semi-active suspension installed with MRF dampers substantially improves the stability and dynamic performance of the train at curve track.

Study on Numerical Simulation Method of Aerodynamic Performance of High-Speed Train on Bridge

The dynamic mesh method that could simulate the actual moving of train was used to calculate the aerodynamic coefficients of train on bridge with wind barriers of various heights, and the static pressure distributions around the train body and velocity magnitude distributions were analyzed, the results computed by dynamic mesh method were compared with that computed by traditional static mesh method. The results show that the aerodynamic coefficients of train and flow field characteristics computed by the two methods agree well under the configuration without wind barriers. However, there is considerable difference between the results computed by the two methods with the installation of wind barriers. It is found that the dynamic mesh method is more reasonable to simulate the aerodynamic coefficients of train with wind barriers by analysis of the contour of static pressure distributions and velocity magnitude distributions. The wind barriers effectively decrease the positive pressure on windward train body and negative pressure on train roof, mainly reduce the side force coefficient, lift force coefficient, rolling moment coefficient. Therefore, the aerodynamic performance of train on bridge under crosswind is improved.

Research on Adhesion and Non-Adhesion Braking Characteristics for High-Speed Train

The emergency braking deceleration and braking distance of high-speed train were studied under the conditions of adhesion brake on dry and humid rail surfaces, and adhesion and non-adhesion composite brake on humid rail surface. The average emergency braking deceleration was calculated by the area-method. The results show that the braking performance is affected significantly by the wheel/rail adhesion state and the braking performance of high-speed train can be improved by applying the adhesion and non-adhesion composite brake in the state of humid rail surface.

Safety Certificate: an audification performance of high-speed trains

Safety Certificate is a musical performance based on sensor data from high-speed trains. The original purpose of this data is to provide a basis for the assessments of the mechanical aspects of train safety. In this performance, the data, which represents dynamical processes below the audible range, are converted into sound through audification. The sound that is generated live during the performance is manipulated through the Manta control interface, which allows for the convenient layering of 48 different timbres. Safety Certificate was premiered at Seconde Nature in Aix-en-Provence in March 2010 during the Sonification symposium–What, Where, How, Why, organized by Locus Sonus. The following short article gives details about the data, the audification technique, use of the control interface, and the musical structure of the performance.