Experimental Study on Flow Field under a High Speed Shinkansen Train

A flow velocity profile under a Shinkansen train car was measured to investigate the flow field, as it is essential in understanding the mechanisms of aerodynamic noise generation. Laser Doppler velocimetry (LDV) was used to measure the area outside of rolling stock gauge. The flow field near the underside of the car was also measured meticulously to clarify inlet conditions to the bogie cavity. It was found that mean flow velocity at a middle car (car #5 from the front car) decreases to 42% of train speed at a point halfway between the underside of the car and the ground, whereas that of a leading car reaches approximately 78% at the same point. It was also found that, at car #5, mean velocity and turbulence level on ballast tracks are slightly higher than that of slab tracks.