Scale of Vortex Structure and Turbulence Property in Impinging Jet

Abstract

The flow field in a turbulent jet impinging on a flat plate is studied. When the two dimensional free jet impinges on the wedge object, so called the edge tone is generated. This accompanies a loud noise and coherent motions. Although most attention has been paid to reveal its mechanisms and control the coherent motions in order to reduce the sound noise, we are interested in the effect of coherent motions on the typical length scale. Adopting the three-component analysis, it was found that coherent motion has a great influence on the integral scale and Taylor micro scale, but has little on the Kolmogorov length scale. Also we focus on the area where the coherent motions survive after impinging on the edge of flat plate. By way of conditional sampling procedure, both the periodic component caused by coherent motions and the non-periodic component are analyzed. The periodic component remains close to wall even far from the top of the plate, but the non-periodic component indicates the large values only around the edge.