Flow Through a Sudden Enlargement Subjected to Large Amplitude Low Frequency Axial Oscillations.

摘要

An experimental investigation was undertaken for the case of flow through a sudden expansion subjected to large amplitude low frequency axial oscillations which formed a standing wave in the receiver duct. Measurements included integrated velocity fluctuation amplitudes and velocity and wall pressure fluctuation amplitudes at the wavemaker frequency. Reattachment of the flow drastically attenuates the fluctuation parameters. Oscilloscope traces show a tendency toward flow relaminarisation during the accelerating phase of the cycle,and a turbulent bursting to high turbulence intensity when the time dependent pressure gradient changes from negative to positive. (Author)