Analysis Of Sound Insulation Performance For The EMU Body Structure

With the rapid development of our country railway enterprise, the EMU has gradually become the main railway passenger transportation for its large capacity, high speed, good safety. Railway aerodynamic noise problem is also becoming increasingly prominent for its high speed. So it’s important to improve the structure’s sound insulation performance, make it the most to reduce the outside noise transmitted into the EMU and make passengers enjoy a quiet and comfortable environment.This paper firstly calculates the aerodynamic noise of the EMU by using the Fluent software, analysis and confirms that the bigger noise parts around the train. Then, study and analysis the sound insulation performance of the EMU’s floor structure and the structure of the passenger compartment side windows by using the acoustic simulation software Actran. The computational fluid dynamics model of the EMU is established, the steady flow field of the EMU is calculated by using of the Fluent software, then the transient fluid dynamics computations are performed using the steady results as a original values, and the aerodynamic noises are achieved using the FW-H acoustic analogy method. Studies have shown that the far field aerodynamic noise of bogie parts is the largest, train head and side wall’s far field aerodynamic noise are also bigger. With the increasing of distance from the train’s surface, aerodynamic noise decays quickly.According to the aerodynamic noise results calculated by using of the Fluent software, the sound insulation performance of the floor structure near the bogie and passenger compartment side window glass are calculated and analysed by using of the Actran software. The incidence acoustic wave is simulated using the diffuse sound field, the transmission side is simulated using the Rayleigh surface, the structure field are scattered using quadratic solid shell element, and the fluid field are scattered using quadratic three-dimensional solid element. The transmitting acoustic energy are calculated by using of the finite element method with Actran software, and then the structure’s sound insulation quantity are calculated. Analysis results shows that the EMU’s aluminum alloy backplane has shown a certain sound insulation performance, it have a good sound insulation effect in the low frequency, especially adding surface damping can improve the sound insulation performance at sound insulation trough; the sound insulation performance can be improved by changing the material parameters or structure parameters of the floor, for example, reducing the elastic porous layer’s porosity, increasing the thickness of the air layer or the thickness of the wood floor layer can also improve the sound insulation performance of the floor structure; Appropriately increasing the passenger compartment side window’s glass gap can improve the sound insulation performance, the sound insulation trough moves to the higher frequency; the appropriate thickness combination of the passenger compartment side window glass has an important effect on sound insulation performance. These studies provide valuable reference on reducing the aerodynamic noise of the EMU and improving the train structure’s acoustic design.