Research On Influence Parameters Of Sound Efficiency Of EMU Air Whistle

The railway industry standards strictly stipulate various parameters of the air whistle for locomotives and EMU.For the current standard EMU,The sound insulation of the shroud affects the external sound field distribution and value.It is very important to ensure that the air whistle can transmit signals safely and effectively in the case of faster and faster train operation.Based on the working principle of air whistle,the two-way fluid-structure interaction is selected as the main research method.The fluid domain inside the air whistle and the diaphragm vibration structure is meshed respectively,and then conducted the modal analysis results.With the help of the Spring Smoothing and Local Remeshing methods in Fluent dynamic mesh,the process from the initial vibration to stable of the air whistle diaphragm is simulated.Through calculation,the relationship between the displacement and stress over time was obtained.Under normal operating conditions,the diaphragm vibration frequency is closed to its natural frequency,and it is approximately equal to the frequency of pressure change at the outlet center.In order to explore the distribution and numerical value of the external sound field,a hemispherical finite element model with a radius of 5m is established to simulate the sound field.The sound pressure level at different monitoring points is calculated and compared with the point sound source.The test system of the air whistle sound field is built,and then measure sound pressure level at different locations under different pressure inlet,which further verified the accuracy of the fluid-structure interaction and the external sound field simulation method.Finally,in order to explore the influence of different parameters on the efficiency of the air whistle sound,the efficiency of pressure inlet,Elastic modulus,Poisson's ratio and diaphragm thickness on the maximum displacement and equivalent stress are obtained respectively.The results show that,within the range specified by the standard frequency,changing the values of the independent variable have a significant effect on the whistle efficiency,which provides theoretical and data support for further design and parameters selection.The main innovation in this paper is the application of the fluid-structure interaction calculation method to the air whistle numerical simulation,which provides a novel and reliable research method and new ideas for the further whistle structure design and optimization.