There are different types of aerodynamic noise generated from various parts of Shinkansen cars. It is now a matter of great concern to analyze and reduce noises from the joint between cars and around the truck. To apply measures towards reducing such noises, the RTRI developed a microphone array close to the mainstream in the open section of wind tunnel in order to accurately locate noise sources (Fig. 1). This array improves the positional identification precision to 10 mm or less from the conventional level of 60 mm, enabling clarification of the detailed distribution of noise sources even in small areas such as the joint between the reduced-scale cars used for wind tunnel tests.
Using this microphone array, the RTRI measured a distribution of the sources of aerodynamic noise emitted from the joint between 1/8-scale Shinkansen car models, and established the presence of noise sources along the angular car ends. With rounded car ends, the noise sources were weaker and noise emitted from the joint between cars dropped by about 7 dB in a wind tunnel test (Figs. 2 and 3).
The RTRI plans to confirm the noise-reducing effect of this modification with actual cars and promote its development for actual use.