Numerical computation of aerodynamic noises of the high speed train with considering pantographs

Abstract

With the improvement of the speed, aerodynamic noises of trains also become more obvious. Reducing the aerodynamic noise has become a key factor to control noises of the high speed train. This paper uses large eddy simulation and boundary element method to compute the flow field and aerodynamic noises of pantographs and trains. The result presents that there are obvious eddies at the head, push rod, and base. Two obvious separation eddies can be found around the guide rod of the head and the push rod of pantographs. The front part of the base has a layer of shear flow, which leads to a separation eddy in the back of the base while the flow moves backward. Noises of pantographs mainly concentrate around the head, base and pushrod. With the increase of the analyzed frequency, the strength of pantograph noise source is weaker and weaker. When the analyzed frequency is 500 Hz, the noise source of pantographs is mainly around joints of several structures. By comparing the computational and the experimental result of aerodynamic noises of pantographs, this result presents that they are consistent with each other in the change tendency and value within the whole analyzed frequency. This indicates that the computational model of aerodynamic noises of pantographs is effective. Pantographs have an obvious influence on the distribution of the flow field around high speed trains, especially at the end of high speed trains. High speed trains with pantographs only have an eddy at the end, but high speed trains without pantographs have two eddies at the end. When this paper conducts on numerical computation for high speed trains, pantographs should not be ignored. In the low frequency, radiation noises of high speed trains can be found mainly around pantographs and at the end of trains. At the longitudinal symmetric plane of high speed trains, the sound pressure level at the end of trains is the highest. The radiation noise around pantographs mainly concentrates around the pushrod, then base, and the last is the head.