Conditional analysis of wall pressure fluctuations in plume-induced separated flowfields

The separation process in plume induced, boundary-layer separated flowfield s was Pound to be unsteady, Two in situ, fast response pressure transducers were used to make individually and simultaneously sampled wail pressure fl uctuation measurements over the Intermittent region of separation shock wav e motion. A conditional analysis technique was applied to the pressure-time histories, and statistical methods Here then used to analyze the period, f requency, and velocity ensembles of the shock motion. The mean frequencies of this motion ranged between 1300 and 1500 Hz over the intermittent region , and the most probable shock wave frequencies occurred between I and 4 kHz over this region. The maximum zero-crossing frequency of the shock wave mo tion was approximately 500-600 Hz. The mean (approximately 3.5% of the free stream velocity) and mast probable (approximately 6% of the freestream velo city) shock wave velocities in either direction were found to be essentiall y constant over the intermittent region. These results are compared to thos e for shock wave/boundary-layer interactions caused by solid protruberances .