Development of Acoustic Measuring Trough for Wind Tunnel

Abstract

A wind tunnel is generally known as a test facility to measure flow property around an automobile, a model of train or so on. On the other hand, recently, measurement of aero-acoustic feature of them is going to be necessary. These measurements are not performed in a same wind tunnel, because the aero-acoustic measurement is only performed in the open wind tunnel and is not done in the closed wind tunnel, which is conventionally used for the flow property measurement. So, this paper describes a unique technique of acoustic measurement with a closed wind tunnel using "acoustic trough". It is made of some specially treated walls, which are consisted of a perforated material and pile-fabric attached on it. Some experimental tests have been conducted to make sure the aero-acoustic feature of the acoustic trough compared with the open wind tunnel. These results show that the acoustic trough is suitable for the aero-acoustic measurement with the closed wind tunnel.