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

Urban electric multiple units EMUs) is based on high speed train s and metro vehicle technology T heir design speeds are generally from 160km/h to 200km/h, which mitigates the low operating speed s of metro vehicles. Traditional crosswind calculations for the aerodynamic characteristics of train s 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 model s of urban trains are established. The train models include 3 marshalling, 4 marshalling and 6 marshalling. The aerodynamic characteristics of 200km/h urban tra ins subject to different crosswind velocit ies 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 car s for different marshalling lengths are significantly different. The side forces of the 4 middle car s of the 6 marshalling train decrease sequentially. At a crosswind velocity of 35m/s, 34% difference in F s of the tail car of a 6 marshalling train com pared 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, t he real marshalling length should be used as far as possible when studying crosswind effects on the train.