Measurement of the flow and its vibration in Japanese traditional bamboo flute using the dynamic PIV

Abstract

All wind instruments produce sound due to the vibration of air inside of the instrument. In the case of a trumpet or a clarinet, the mouth or a reed helps to generate variable tones. In the case of a flute, there is no mechanical vibration. Additional detail about the flow and the sound vibration inside and outside of the flute are investigated in order to understand the mechanism of the wind instrument and to aid in the manufacture of quality instruments. In this report, a traditional Japanese bamboo flute was investigated experimentally. The dynamic PIV technique was applied to measure the vibration. Two kinds of experiments were performed. Argon-gas flow containing an oil mist as tracer particles both inside and outside the bamboo flute was measured using a high frequency pulse laser. The periodical flow near a hole of the bamboo flute was successfully measured. The flow was found to go into and out from the flute and the balance of a mass flow rate and the averaged velocity were almost zero at the hole. Then, the flow in the bamboo flute was visualized when a human played the instrument, using a CW-laser and water-mist as the tracer. It was discovered that the two instructors had unique methods for playing the flue instrument.