AERODYNAMIC testing of noise generated by shinkansen trains can now be undertaken in Japan Railway Technical Research Institute’s new wind tunnel at Maihara-cho. Work has already been carried out on JR West’s Series 500, and testing of components such as pantographs has proved particularly useful.
Measuring the noise generated by air flow over a train or component profile is made possible by an extremely low level of noise in the anechoic test chamber, measuring 22m x 20m x 13 m high and lined with sound-absorbent material. Background noise is 75dB(A) at a wind velocity of 300 km/h.
Measurement of aero-acoustic noise takes place with the wind tunnel in its open configuration; an 8m portion of the 228m circuit is open to the chamber where a sound level meter, linear array microphone and parabola microphone are deployed. A maximum wind velocity of 400 km/h is generated by a 5m diameter fan with 12 moving and 17 stator blades, which rotates at up to 550rev/min and is powered by a 7MW three-phase motor.
With the wind tunnel in enclosed configuration, aerodynamic testing is undertaken at wind speeds of up to 300 km/h. To simulate air flows between moving vehicles and the ground, models are suspended over a belt measuring 6m x 2·7m which moves at up to 60m/s. Flow visualisation is achieved by means of a smoke generator, specialised lighting and video monitoring.
Railway Technical Research Institute, Japan, Reader Enquiry Form Number 141
CAPTION: The anechoic test chamber at Maihara-cho, with the wind tunnel in the open position for aero-acoustic noise testing. Models are placed on a raised platform in front of the smaller hood (right) Photo: RTRI
