Numerical Simulations Investigations of Flow Fields Underneath the High Speed Trains

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High-Speed Trains

Complexity ◽

10.1155/2018/6932596 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 5

Author(s):

Xiaoqi Sun ◽

Han Xiao

Keyword(s):

High Frequency ◽

High Speed ◽

Sound Pressure ◽

Noise Source ◽

Flow Fields ◽

Aerodynamic Noise ◽

Far Field ◽

Frequency Bands ◽

Noise Characteristics ◽

High Speed Trains

Pantographs are important devices on high-speed trains. When a train runs at a high speed, concave and convex parts of the train cause serious airflow disturbances and result in flow separation, eddy shedding, and breakdown. A strong fluctuation pressure field will be caused and transformed into aerodynamic noises. When high-speed trains reach 300 km/h, aerodynamic noises become the main noise source. Aerodynamic noises of pantographs occupy a large proportion in far-field aerodynamic noises of the whole train. Therefore, the problem of aerodynamic noises for pantographs is outstanding among many aerodynamics problems. This paper applies Detached Eddy Simulation (DES) to conducting numerical simulations of flow fields around pantographs of high-speed trains which run in the open air. Time-domain characteristics, frequency-domain characteristics, and unsteady flow fields of aerodynamic noises for pantographs are obtained. The acoustic boundary element method is used to study noise radiation characteristics of pantographs. Results indicate that eddies with different rotation directions and different scales are in regions such as pantograph heads, hinge joints, bottom frames, and insulators, while larger eddies are on pantograph heads and bottom frames. These eddies affect fluctuation pressures of pantographs to form aerodynamic noise sources. Slide plates, pantograph heads, balance rods, insulators, bottom frames, and push rods are the main aerodynamic noise source of pantographs. Radiated energies of pantographs are mainly in mid-frequency and high-frequency bands. In high-frequency bands, the far-field aerodynamic noise of pantographs is mainly contributed by the pantograph head. Single-frequency noises are in the far-field aerodynamic noise of pantographs, where main frequencies are 293 Hz, 586 Hz, 880 Hz, and 1173 Hz. The farther the observed point is from the noise source, the faster the sound pressure attenuation will be. When the distance of two adjacent observed points is increased by double, the attenuation amplitude of sound pressure levels for pantographs is around 6.6 dB.

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The Grid Strategy of High Reliable Numerical Simulations for Aerodynamic Performance of High-Speed Trains

Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance ◽

10.4203/ccp.104.25 ◽

2014 ◽

Author(s):

C.W. Jiang ◽

Z.X. Gao ◽

J.S. Yang ◽

C.H. Lee

Keyword(s):

Numerical Simulations ◽

High Speed ◽

Aerodynamic Performance ◽

High Speed Trains

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Numerical Simulations of Dynamic Responses of High-Speed Trains to Random Track Irregularities

Sustainable Development of Critical Infrastructure ◽

10.1061/9780784413470.030 ◽

2014 ◽

Cited By ~ 1

Author(s):

Mengyi Zhu ◽

Xiaohui Cheng ◽

Lixin Miao

Keyword(s):

Numerical Simulations ◽

High Speed ◽

Dynamic Responses ◽

High Speed Trains ◽

Random Track Irregularities ◽

Track Irregularities

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High-speed trains: in microchannels?

Journal of Fluid Mechanics ◽

10.1017/jfm.2016.51 ◽

2016 ◽

Vol 792 ◽

pp. 1-4 ◽

Cited By ~ 3

Author(s):

Jeffrey F. Morris

Keyword(s):

Numerical Simulations ◽

High Speed ◽

Particle Concentration ◽

Hydrodynamic Interactions ◽

Suspension Flow ◽

Rectangular Microchannel ◽

Inertial Focusing ◽

High Speed Trains ◽

Particle Ordering

Kahkeshani et al. (J. Fluid Mech., vol. 786, 2016, R3) have studied particle ordering in suspension flow in a rectangular microchannel. Experiments and numerical simulations reveal that inertial focusing and hydrodynamic interactions result in long-lived ‘trains’ of regularly spaced particles. The preferred spacing is frustrated at sufficient particle concentration, an important feature for applications.

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