Influence of Marshalling Length on Aerodynamic Characteristics of Urban Emus under Crosswind

Urban electric multiple units (EMUs) is based on high-speed trains and metro vehicle technology. Their design speeds are generally from 160km/h to 200km/h, which mitigates the low operating speeds of metro vehicles. Traditional crosswind calculations for the aerodynamic characteristics of trains often assume a 3-marshalling train. Urban trains are generally 4-marshalling and 6-marshalling. Evaluating the aerodynamic characteristics of urban EMUs of different marshalling lengths is instructive for system design. Based on CFD, aerodynamic models of urban trains are established. The train models include 3-marshalling, 4-marshalling and 6-marshalling. The aerodynamic characteristics of 200km/h urban trains subject to different crosswind velocities are numerically simulated. The research display that the aerodynamic performance of the head-car and the first middle-car, under the same crosswind velocity, of different marshalling lengths, are almost the same, whereas the aerodynamic characteristics of the tail-cars for different marshalling lengths are significantly different. The side forces of the 4 middle-cars of the 6-marshalling train decrease, sequentially. At a crosswind velocity of 35m/s, 34% difference in Fs of the tail-car of a 6-marshalling train compared to a 3-marshalling, and the overturning moment differs by 22.8%. Because of the significant difference in side force and overturning moment, the three-marshalling train model cannot represent the real train. Therefore, the real marshalling length should be used, as far as possible, when studying crosswind effects on the train.

Influence of Marshalling Length on Aerodynamic Characteristics of Urban Emus under Crosswind Keywords:

Crosswind , Marshalling length , Train aerodynamics , Urban trains , Numerical simulation