抄録
In this study, in order to examine the noise measurement technique of the internal flow, the flow noise due to vortex shedding from a circular cylinder was measured by use of a suction type wind tunnel which was equipped with glass wool walls and a condenser microphone. As a result of experiments, it was found that the acoustical free space can be created when the glass wool was set in the test section of wind tunnel, and the measurement of the fluid sound of the internal flow became possible without disturbing a flow field by incorporating a condenser microphone into the glass wool wall. A sound frequency with one big sound pressure level was measured when measuring a fluid sound from a circular cylinder in the fluid flow and the other frequency ingredient was a level as much as the background noise.
