抄録
The process of the separation was investigated experimentally in the single-side expansion type diffuser. The inclined wall of the diffuser was opened with time at constant angular velocity. The flow visualization by tufts on the inclined wall shows that the separation bubble grows before separation. The surface pressure fluctuation on the inclined wall was amplified before separation. FFT analysis of the pressure fluctation shows the particular spectrum peak about 500 Hz, This "precusor signal of separation" was found to be related the instability due to an inflection point of the velocity profile. Then, transition into the turbulent flow occur in the diffuser.
