10304 はく離の前兆となる流れ場変動(流体(1))

Abstract

Jets issuing through small holes in a wall into a freestream have proven effective in the control of flow separation. This technique is known as the vortex generator jet method (VGJ). If a precursor signal of separation is found, the separation control system using VGJ can be operated just before the onset of separation. Therefore, flow field with no separation is always attained. In this study, we measured the flow field and the wall static pressure in a two-dimensional diffuser. Flow separation occurs when the divergence angle reaches at 18 degrees. The streamwise velocity measurements were carried out in the separated shear layer and the spectral analysis was applied to the velocity fluctuations at some angle of diffuser. The pattern of peak in the spectral analysis is changed as the divergence angle increases over 18 degrees due to the enhancement of the growth of the shear layer vortices.