Design Of High-speed Trains Research Articles

Ventilation performance study of a high-speed train cabin based on displacement ventilation and mixed ventilation

Indoor ventilation systems play an important role in controlling energy consumption, thermal comfort, and airborne pollutants. This work is concerned with whether the combination of displacement and mixed ventilation can overcome these systems' respective shortcomings to improve the ventilation performance of high-speed train cabins. This work is based on computational fluid dynamics. The results show that when more fresh airflow enters the compartment from the top vents, the flow field is mainly driven by mechanical forces, and two vortices are formed. When more fresh airflow enters the compartment from the bottom vents, the flow field is mainly driven by thermal buoyancy. Meanwhile, the airflow mainly spreads upward, with lower cooling energy consumption, lower wind speed, higher ventilation efficiency, and smaller longitudinal diffusion of pollutants, but increased temperature difference. When the ratio of top and bottom supply air flow is 75%/25%, thermal comfort can be improved, while balancing energy consumption and air quality. If there was a disease outbreak, the flow rate of the bottom air supply could be increased appropriately. To further improve the ventilation performance, on the one hand, it is necessary to appropriately increase the temperature of the bottom air supply, and on the other hand, it is necessary to avoid short-circuiting of the airflow, due to the lack of synergy between thermal buoyancy and mechanical force. The results of the study can provide a reference for safeguarding passengers and improving the ventilation design of high-speed trains.

Investigations on the Johnson-Cook Constitutive and Damage-Fracture Model Parameters of a Q345C Steel

Due to the rapid development of high-speed trains, the service safety of vehicle body materials and structures has become a focal point in transport and impact engineering. Numerical simulations on the collision resistance of vehicle materials and structures are crucial for the safety assessment and optimal structural design of high-speed trains but have not been fully investigated due to the lack of damage model parameters. This study focuses on the Johnson-Cook (J-C) constitutive and damage-fracture models of a typical vehicle material, Q345C steel. A series of mechanical tests are conducted on the Q345C steel, including the quasi-static and dynamic compression/tension tests, quasi-static tension tests at different temperatures, and fracture tests along different stress paths, using the material test system and the split Hopkinson pressure/tension bar. Then, the parameters of the Johnson-Cook constitutive and damage-fracture models are calibrated based on the experimental results. In terms of the damage parameters related to stress paths, a new method of combining experiments and simulations is proposed to obtain the real, local fracture strains of the Q345C steel samples. This method allows the measurements of equivalent plastic strain and stress triaxiality histories under nonlinear stress paths, which are hardly accessible from individual experiments, and facilitates the accurate calibration of stress-path-related damage parameters. In addition, a high-speed plate penetration test is used to validate the J-C parameters, which can be directly implemented in the commercial finite element software Abaqus. The projectile trajectories from the simulation and experiment agree well with each other, demonstrating the reliability of the model parameters for impact scenarios and the efficiency of the experimental procedures utilized for calibration.

Investigation on the time/frequency domain prediction model of radiation noise based on the source map

The main exterior noise sources of the high-speed train CRH380AM, such as pantograph and bogie, are studied by using the field test sound imaging data, and the equivalent point source spectrums are obtained here. Then, the prediction model of the exterior train noise is presented by using the moving point sound source radiation model in the time/frequency domain. The correctness and effectiveness of the model are verified by the field test data. The radiation contribution of local noise sources is analyzed by using this model, and the following conclusions are obtained: The largest noise sources are in the bogie areas, which provide the radiation contribution rate of about 80% when the train speed is above 300 km/h. The variation of the maximum radiation noise level can be ignored when the train formation or the pantograph lifting position is changed. The model can evaluate the radiated noise of similar vehicles quickly and accurately, which provides technical reference for acoustic optimization design of high-speed train.

Robust optimisation of the streamlined shape of a high-speed train in crosswind conditions

Traditional deterministic aerodynamic optimisation cannot consider environmental uncertainty, which may lead to sensitivity issues. The present study proposes a robust design framework for the aerodynamic optimisation of high-speed trains, which accounts for the uncertain wind and its impact on crosswind stability. In this framework, a variance analysis method based on the Non-Intrusive Polynomial Chaos is proposed to determine the deformation area, and a parametric model is subsequently established. The Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is used as the optimiser to minimise the mean and variance of the aerodynamic response. The mean and variance can be quickly predicted by an uncertainty analysis approach combining Monte Carlo simulation and Kriging model. The framework is then applied to the optimisation of a high-speed train under crosswind. The results of the robust optimisation are compared with those of the baseline geometry and deterministic optimisation. The mean and variance of the rolling moment under crosswind are reduced by 2.26% and 3.37% respectively after optimisation, indicating that the performance and robustness are both improved. The proposed framework is effective for the engineering design of high-speed trains and can also provide a reference for the robust design of other aerodynamic shapes.

Numerical Analysis for Different Masks of Car Design of High-Speed Train

Indonesia is developing a high-speed train (HST) prototype planned for a maximum speed of 250 km/h. In high operating speed, an aerodynamics drag contributes significantly to the total resistance. Thus, reducing the aerodynamic drag becomes a primary concern. One of the significant aspects that need to be solved is to design the optimum shape of the frontal nose of the train called the Mask of Car (MoC). This research aims to study the drag coefficient from the various shape of the HST Mask of Car design by numerical method and to develop the optimum design strategy. The curvature parameters of the complex 3D model, such as nose-length, upper curvature, and side-curvature used as an optimization method The base model was constructed in 2D parameters and then developed into different shapes using 3D CAD software. A set of models was then analyzed using computational fluid dynamics with the coefficient of drag and flow characteristic. Based on the iterative simulation, it is discovered that the longer nose and sharper side of the MoC will reduce the aerodynamic drag. In conclusion, the length and the slenderness of the nose shape are significant factors in designing the mask of car of high-speed train.

Pedigree Aerodynamic Shape Design of High-Speed Trains

The aerodynamic performance of high-speed trains is closely related to their head shape. As each train set has its own modelling system, the aerodynamic shape design of head type of a high-speed train must follow a pedigree modelling approach. The train pedigree characteristics directly reflect its aerodynamic performance. The focus of this study is the extraction and application of the Shinkansen train pedigree features. First, large-scale differences in train head shapes are eliminated by dimensionless elimination. Second, the Shinkansen model pedigree features are extracted using similarity calculations. Finally, based on the constraint range of pedigree features on the new model shape, the concept head shape is designed with reference to the shape and surface parameters of high-speed trains, and its aerodynamic performance is verified. The results of the aerodynamic verification indicate that the concept design reduces the drag by more than 10% compared to the E2 Series base model. Additionally, the results demonstrate that the extraction and design application of train pedigree features can help a new train to develop its aerodynamic shape within its own pedigree modelling system, thus enabling the synergistic design of train shape and aerodynamic performance.

Jointing of CFRP/5083 Aluminum Alloy by Induction Brazing: Processing, Connecting Mechanism, and Fatigue Performance

Carbon fiber reinforced polymer (CFRP) is widely used in the lightweight design of high-speed trains due to its high specific strength. In order to further reduce the weight of the high-speed train body, it is necessary to study the joining process and fatigue properties of CFRP/aluminum alloys (CFRP/Al) structure. In this work, the CFRP plate and 5083P-O aluminum plate were successfully connected by an induction brazing method. The optimum parameters of induction brazing were determined to be an induction temperature of 290 °C, a normal pressure of 200 kPa, and a holding time of 5 s. After the 5083 plate was pre-anodized, the tensile strength of the CFRP/5083 joint reached a maximum value of 176.5 MPa. The anodization process introduced more surface micro-structures on the 5083 plate, leading to a better wetting behavior between CFRP and oxide film. Meanwhile, a new chemical bond, Al-O-C, was also formed at the interface of the CFRP/5083 joint. The fatigue limit of the CFRP/5083 joint was calculated to be 71.68 MPa through high-cycle fatigue (HCF) testing. The fatigue cracks initiated from the interface of CFRP/oxide film, and then propagated to base metal. Finally, the oxide film was peeled off from the base metal under shear stress, which contributed to the fracture of the CFRP/5083 joint. The bonding strength between CFRP and 5083 aluminum alloy is far from the conventional welded joints. Therefore, feasible approaches should be proposed to obtain a more robust bonding between CFRP and aluminum alloy in the future.

Improved particle swarm optimization algorithms for aerodynamic shape optimization of high-speed train

In this paper, improved particle swarm optimization algorithms are presented for improving the aerodynamic optimization efficiency of a high-speed train head shape. A hybrid particle swarm optimization algorithm, which employs an artificial fish swarm algorithm (AFSA) and a backward learning strategy in particle swarm optimization, is first proposed for constructing an optimal least squares support vector regression (OPT-LSSVR) model. The prediction accuracy of various surrogate models was evaluated, and the results indicate that the OPT-LSSVR model has the smallest prediction errors, where the prediction error for the total aerodynamic drag coefficient is reduced to about 0.45% and reduced to within 5% for the lift coefficient. Besides, an elite-evolved multi-objective particle swarm optimizer (EMPSO), which employs a grouping-based stochastic elite competition mechanism and elite gathering behavior, is proposed to improve the multi-objective optimization efficiency. The verified results indicate that the EMPSO algorithm is more efficient and capable of tackling complex multi-objective problems. Based on the OPT-LSSVR model and the EMPSO algorithm, the aerodynamic shape optimization of the high-speed train is performed. After optimization, the aerodynamic drag coefficient and the aerodynamic lift coefficient are reduced by 3.63% and 10.59%, respectively. Improved algorithms are simple yet efficient, and they have significant implications for the research and design of high-speed trains at higher speeds.

Analysis of Aerodynamic Characteristics of High-speed Train with Asymmetric Heads

High-speed transportation is closely related to people’s livelihood and national economy, so it becomes an important development aspect to the whole country. The safety, comfort and economy of high-speed train are the key consideration during its design process. In the future, new trains and old ones will be used for a long time, and the performance of new trains which run on the old lines may be limited. These situations make the research of high-speed train with asymmetric heads much necessary. Aiming at the feasibility of the train with asymmetric heads, the heads of train CRH3 and another typical train with a similar speed are selected. Based on the two heads, the digital models of the traditional trains with symmetric heads and the new trains with asymmetric heads are built firstly. And then their aerodynamic characteristics are computed by the SIMPLE method. In the numerical part, the performances of the trains are compared on the condition without crosswind, which shows that one of the new trains with asymmetric heads is the best among them. Moreover, the aerodynamic characteristics of this new model under crosswind is analyzed, which demonstrates that the train with asymmetric heads is feasible. The research shows that the train with asymmetric heads can achieve better results through the proper aerodynamic shape optimization design, which presents an idea for the future high-speed train design.

Simulation Analysis of Complex Aluminium Alloy Structural Component of High-Speed Train

High-speed trains are now the most important medium- and long-distance mode of transport in many countries, and green economy is one of the important directions of high-speed train design. Aluminum alloy material is widely used in various structural parts of high-speed trains due to its advantages of high strength and low density, etc. As the speed of high-speed trains is getting faster and faster, the load on the car body structure is getting bigger and bigger, the safety, reliability and longevity of aluminum alloy structure has received wide attention. In this paper, the stress distribution, maximum stress value and maximum stress point position of aluminum alloy structural members of high-speed trains are analyzed in detail based on the real load situation, and the influence of stress level on train operation is analysed. The above work has certain reference significance for the design of high-speed train.

Energy consumption analysis and multiple-criteria evaluation of high-speed trains with different marshaled forms in China

Because of the current state of global resource shortages and environmental degradation, energy-saving and environmentally friendly national policies and low-carbon concepts have attracted both individual and societal attention, especially for rail transit. The rapid development of high-speed railways and urban rail transit in China has presented increasing transport energy demands and environmental pressures. This paper conducts an energy consumption comparative analysis of high-speed trains with different marshaled forms, including 3, 5, 8, 10, 12, 16, 17 and 18 cars, using the delayed detached eddy simulation method. A wind tunnel test with a 3.6% difference is applied to verify the obtained numerical results. A multiple-criteria evaluation methodology is presented to select the optimal alternatives for the marshaled forms of high-speed trains, which considers economic, social and environmental factors. The 1318-km (820-mile) Beijing-Shanghai line and a 350-kph high-speed train are employed in this research. The results can effectively guide the engineering design of high-speed trains and provide an evaluation tool in the decision-making process for designers.

Application Research of Design Geometry in the Design of High Speed Trains

The visual characteristics of high-speed trains in China are comparatively not at an advantage, while vehicle serialization and product identification remains to be a major problem. From the perspective of design geometry, This paper analyzes the mathematical composition of modeling curves in foreign excellent models, summarizes the geometric proportional relationship of the vehicle system, innovates a design and operation method of the vehicle body shape, and establishes a new generation of model design based on the geometric law of the line shape of vehicle body so as to enhance the viability of vehicle serialization, and provide a basic premise for design strategy research.

Research on multidisciplinary fatigue optimization design method in structural design of high speed train

Aiming at the shortcomings of single-discipline fatigue design and life prediction optimization design method for high-speed trains, considering the characteristics of structural design integrity, a durability analysis method for key structural components based on multi-disciplinary fatigue optimization design is proposed. According to the characteristics of vibration fatigue and structural failure of key structural components of high-speed trains, the multi-disciplinary fatigue design of carbody components is carried out from the perspectives of materials, loads and structural design. In the research process, qualitative and quantitative analysis and comparison of multi-objective optimization analysis (MOO) and multi-disciplinary optimization (MDO) processes were carried out. At the same time, considering the actual example, considering the vibration characteristics of the vehicle structure, the typical load spectrum and the complex material characteristics, the failure characteristics of the structural components are analyzed in detail. The research results are shown that there are certain limitations in single-disciplinary fatigue design and analysis. In order to effectively solve the complex engineering structure failure problem, it is necessary to fully consider the vibration characteristics of the entire vehicle structure. Through the multi-disciplinary fatigue design and optimization method of high-speed train structural components, the safety and structural integrity of key structural components of rail transit can be better guaranteed.

철도차량 통과 시 터널 내부 유동장 해석을 위한 무격자기법의 적용에 관한 연구

We developed a computational fluid analysis program that can perform flow analysis when a high - speed railway vehicle passes through a tunnel by applying meshless computational technology in this study. The program was verified by comparing transonic RAE 2822 airfoil with experimental measurement results and numerical analysis results. From the proven analytical techniques, we propose the behavior of the high - speed trains moving into the tunnel by using the meshless - based computational fluid technique as a dedicated analysis tool that can be easily used even by the novice users. We compared the pressure generated during the passage of a high-speed train using this analysis technique with the results of C-STASUPTM/SUP, which is a conventional program for high-speed train design. In the case of the tunnel without shaft tunnel, it shows the same result as the existing C-STASUPTM/SUP and the result of this development program, showing the possibility of using this program using the meshless technique as a dedicated program for railway vehicles.

Application of the Bionic Concept in Reducing the Complexity Noise and Drag of the Mega High-Speed Train Based on Computer Simulation Technologies

Regarding the continuous development of high-speed trains and the increase of running speeds, the aerodynamic design of high-speed trains has become significantly important, while reduction of drag and noise comprises a significant challenge in order to optimize aerodynamic design of high-speed trains. The design form factor of a high-speed train is highly influenced by aerodynamic aspects including aerodynamic drag, lift force, and noise. With the high-speed train as the object, the paper aims to take bionic concept as the entry point, selecting the hummingbird as the bionic prototype and extracting bionic elements to establish a bionic train model. Then, the finite volume method was used for numerical simulation and analysis of the aerodynamic performance and aerodynamic noise of the bionic high-speed train. Computational results prove that drag and noise of the bionic head type were lower than those of the original train; drag of the head train of the bionic model was reduced by 2.21% in comparison with the original model, while the whole-train drag was reduced by 3.53%, indicating that drag reduction effects are available and implying that the bionic head type could reduce drag and noise. Noise sources of the bionic train are mainly located at positions with easy airflow separation and violent turbulence motion. Large turbulence energy is in bogie areas and mainly exists at the leeward side of the bogie area. Obviously, the bogie area is the major noise source of the train. Aerodynamic noise of the bionic train in far-field comprises a wide-frequency range. Noises were concentrated within 613 Hz~3150 Hz. When the bionic high-speed train ran at 350 km/h, through comparative analysis of total noise levels at observed points of the high-speed train, it is found that this position with the maximum noise level was 25 m away from the head train nose tip, with the maximum value of 88.4 dB (A). When the bionic train ran at 600 km/h, the maximum sound pressure level at the longitudinal point was 99.7 dB (A) and the average noise level was 96.6 dB (A). When the running speed increased from 350 km/h to 600 km/h, the maximum noise level increased by 11.3 dB (A) and the average noise level increased by 11.6 dB (A). Computation results of aerodynamic noise at the point which is 7.5 m away from the rail center show that the maximum aerodynamic noise level existed at the first-end bogie of the head train, while the noise level was larger at the position closer to the ground.

Boundary Layer Control at Moving Train Models for Slipstream Investigations

Trackside induced airflow velocities are an important criterion for the design of high-speed trains. Due to the limited model size and different Reynolds numbers in moving model experiments, the induced flow may not be comparable to real trains. The idea is to control the thickness of the boundary layer using roughness elements. High-Speed PIV and conditional sampling are used to analyze the size and dynamics of the flow structures at the time of maximum velocity. The roughness elements effect the boundary layer and the flow structure at a lower measurement height by increasing the average and maximum velocity.

A Systematic Optimization Design Method for Complex Mechatronic Products Design and Development

Designing a complex mechatronic product involves multiple design variables, objectives, constraints, and evaluation criteria as well as their nonlinearly coupled relationships. The design space can be very big consisting of many functional design parameters, structural design parameters, and behavioral design (or running performances) parameters. Given a big design space and inexplicit relations among them, how to design a product optimally in an optimization design process is a challenging research problem. In this paper, we propose a systematic optimization design method based on design space reduction and surrogate modelling techniques. This method firstly identifies key design parameters from a very big design space to reduce the design space, secondly uses the identified key design parameters to establish a system surrogate model based on data-driven modelling principles for optimization design, and thirdly utilizes the multiobjective optimization techniques to achieve an optimal design of a product in the reduced design space. This method has been tested with a high-speed train design. With comparison to others, the research results show that this method is practical and useful for optimally designing complex mechatronic products.

Product Data Model for Performance-driven Design

When designing large-sized complex machinery products, the design focus is always on the overall performance; however, there exist no design theory and method based on performance driven. In view of the deficiency of the existing design theory, according to the performance features of complex mechanical products, the performance indices are introduced into the traditional design theory of “Requirement-Function-Structure” to construct a new five-domain design theory of “Client Requirement-Function-Performance-Structure-Design Parameter”. To support design practice based on this new theory, a product data model is established by using performance indices and the mapping relationship between them and the other four domains. When the product data model is applied to high-speed train design and combining the existing research result and relevant standards, the corresponding data model and its structure involving five domains of high-speed trains are established, which can provide technical support for studying the relationships between typical performance indices and design parameters and the fast achievement of a high-speed train scheme design. The five domains provide a reference for the design specification and evaluation criteria of high speed train and a new idea for the train’s parameter design.

Analysis of Equipment & Body Vertical Coupled Vibration Characteristics Based on Excitation of Single Bogie

It is the inevitable trend for the development of railway vehicles in China, which is high speed and heavy haul. But high Speed and heavy load operation condition will also worsen the running environment of whole vehicle system and components or assemblies, which will be a threat to the running safety. Meanwhile, vibration problem caused by high speed running will become more and more prominent. Railway vehicle is a complexity dynamic system with multidimensional and multi-DOF, and its dynamic performance is the key factor to the running safety and stability. So, study on the dynamic characteristics between body and equipment is of key technologies for the design of high-speed train.

High-Speed Particle Image Velocimetry of the Flow around a Moving Train Model with Boundary Layer Control Elements

Trackside induced airflow velocities, also known as slipstream velocities, are an important criterion for the design of high-speed trains. The maximum permitted values are given by the Technical Specifications for Interoperability (TSI) and have to be checked in the approval process. For train manufactures it is of great interest to know in advance, how new train geometries would perform in TSI tests. The Reynolds number in moving model experiments is lower compared to full-scale. Especially the limited model length leads to a thinner boundary layer at the rear end. The hypothesis is, that the boundary layer rolls up to characteristic flow structures in the train wake, in which the maximum flow velocities can be observed. The idea is to enlarge the boundary layer using roughness elements at the train model head so that the ratio between the boundary layer thickness and the car width at the rear end is comparable to a full-scale train. This may lead to similar flow structures in the wake and better prediction accuracy for TSI tests. In this case, the design of the roughness elements is limited by the moving model rig. Small rectangular roughness shapes are used to get a sufficient effect on the boundary layer, while the elements are robust enough to withstand the high accelerating and decelerating forces during the test runs. For this investigation, High-Speed Particle Image Velocimetry (HS-PIV) measurements on an ICE3 train model have been realized in the moving model rig of the DLR in Gottingen, the so called tunnel simulation facility Gottingen (TSG). The flow velocities within the boundary layer are analysed in a plain parallel to the ground. The height of the plane corresponds to a test position in the EN standard (TSI). Three different shapes of roughness elements are tested. The boundary layer thickness and displacement thickness as well as the momentum thickness and the form factor are calculated along the train model. Conditional sampling is used to analyse the size and dynamics of the flow structures at the time of maximum velocity in the train wake behind the train. As expected, larger roughness elements increase the boundary layer thickness and lead to larger flow velocities in the boundary layer and in the wake flow structures. The boundary layer thickness, displacement thickness and momentum thickness are increased by using larger roughness especially when applied in the height close to the measuring plane. The roughness elements also cause high fluctuations in the form factors of the boundary layer. Behind the roughness elements, the form factors rapidly are approaching toward constant values. This indicates that the boundary layer, while growing slowly along the second half of the train model, has reached a state of equilibrium.