Wind Tunnel Tests on Aerodynamic Noise from the Head Car of a High-speed Train

Characteristics of aerodynamic noise is always difficult to extract by both experimental and numerical methods. Based on the aero-acoustic wind tunnel test results of a 1:8 scale high-speed trains model with three cars, the properties of the aerodynamic noise sources of the head car were analyzed. In view of the fact that dipole source is the main aerodynamic noise source of the high-speed train, the acoustic similarity relationship between the different models was deduced. Subsequently, the aerodynamic noise properties of the 1:1 scale model (approximate full-scale train) were analyzed. The results show that the main noise sources of the 1:1 scale model are the bogie regions and the noise energy of 80 Hz–4 kHz is dominant at the train speed of 250 km/h. The noise is the strongest at the frequency of 160–400 Hz, and the noise of the nose tip and the obstacles is the same order as that of the bogie area after 2.5 kHz. The acoustic similarities between the different models are related to the third power of the speed, and the first power of the model length, the propagation distance and the frequency. The noise difference between the different models is related to scale size and frequency. The frequency at full scale has an exponential relationship with the scale model’s frequency, not following a liner relationship with the scale.