Multi objective optimization of aerodynamic design of high speed railway windbreaks using Lattice Boltzmann Method and wind tunnel test results

2018 ◽  
Vol 6 (3) ◽  
pp. 183-201 ◽  
Author(s):  
Masoud Mohebbi ◽  
Mohammad Ali Rezvani
Author(s):  
R. Kamali ◽  
A. H. Tabatabaee Frad

It is known that the Lattice Boltzmann Method is not very effective when it is being used for the high speed compressible viscous flows; especially complex fluid flows around bodies. Different reasons have been reported for this unsuccessfulness; Lacking in required isotropy in the employed lattices and the restriction of having low Mach number in Taylor expansion of the Maxwell Boltzmann distribution as the equilibrium distribution function, might be mentioned as the most important ones. In present study, a new numerical method based on Li et al. scheme is introduced which enables the Lattice BoltzmannMethod to stably simulate the complex flows around a 2D circular cylinder. Furthermore, more stable implementation of boundary conditions in Lattice Boltzmann method is discussed.


2019 ◽  
Vol 11 (7) ◽  
pp. 168781401986399 ◽  
Author(s):  
Hee-Min Noh

A pantograph in contact with a catenary for power supply is one of the major aerodynamic noise sources in high-speed trains. To reduce pantograph noise, it is essential to understand the noise generation mechanism of the pantograph. However, it is difficult to determine this mechanism through measurement. Therefore, in this study, the aerodynamic and acoustic performances of a pantograph in a high-speed train were investigated through numerical analysis using the lattice Boltzmann method. First, a real-scaled pantograph was modeled through computer-aided design. Then, the surface and volume meshes of the pantograph model were generated for simulation analysis. Numerical simulation was conducted at a speed of 300 km/h based on the lattice Boltzmann method. Based on the time derivative analysis of flow pressures, it was concluded that the panhead, joint, and base were the dominant noise sources in the pantograph. In particular, various vortexes were generated from the metalized carbon strip of the panhead. The peaks of the sound pressure level propagated from the panhead were 242, 430, and 640 Hz. The noise generation mechanism was analyzed through numerical simulation using noise characteristics.


Author(s):  
Masoud Mohebbi ◽  
Mohammad A Rezvani

This research is concerned with identifying the effects of windbreak geometry on attenuating aerodynamic loads that can be strong enough to disturb the running safety of high-speed trains. The idea is to suggest the proper geometry for the windbreaks that can make them more efficient and increase their overall performance. Generally speaking, the desired windbreak is the one that can minimize the aerodynamic forces on the surface of trains. In order to reach such an aim, the flow of air around an Intercity-Express 3 high-speed train has been estimated through a two-dimensional modeling by using the lattice Boltzmann method. The flow of crosswind that hits the train is considered as turbulent. The geometry of the windbreaks including the height, the slot, and the edge angles has been investigated. It has been concluded that the windbreak performance, among other parameters, is highly dependent on its height and edge angle. This research expedites the trail for finding suitable choices of windbreak geometries that can in turn provide a reliable degree of running safety of the railway fleet.


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