Numerical study on the aerodynamic and acoustic scale effects for high-speed train body and pantograph

Abstract

Based on computational fluid dynamics (CFD) and Lighthill acoustic analogy theory, the aerodynamics and acoustic scale effects of high-speed train bodies and pantographs are numerically studied, by changing the model scale. The model scales are 1/1, 1/2, 1/4 and 1/8 respectively. The aerodynamic force, flow field behavior, surface pressure and far-field noise of the train body and pantograph models, at different model scales are compared and analyzed. The numerical simulation is in good agreement with the experiment. The reliability of the numerical calculation method has been proven. The results show that as the scale of the model decreases, the root mean square (RMS) value and the degree of fluctuation of the aerodynamic drag coefficient of the pantograph increase. In addition, the aerodynamic drag coefficient of the train body increases, but the degree of fluctuation decreases. The similarity of the unsteady flow field of the pantograph at different model scales is strong, but the similarity of the train body is weak. The main frequency and power spectral density distribution of the pulsating pressure on the surface of the pantograph have obvious corresponding relationships with the model scale, but the train body has no obvious regularity. The longitudinal and lateral propagation characteristics of aerodynamic noise from the train body and pantograph are not affected by the model scale, but the sound pressure level changes. Compared with the train body, the far-field aerodynamic noise of the pantograph is less affected by the model scale. The energy distribution of noise is also affected by the scale of the model. As the model scale decreases, the energy concentration range of radiated noise will change from low frequency to medium high frequency.