EFFECT OF FREE-STREAM TURBULENCE ON TURBULENT PROPERTIES OF A SEPARATION-REATTACHMENT FLOW

Abstract

Studied in this paper is the effect of free-stream turbulence on the turbulent structure of a separation bubble formed at the leading edge of a blunt plate with right-angled corners. The free-stream turbulence was introduced by a thin circular rod placed upstream of the plate along its stagnation streamline. This paper is sequel to the authors' previous papers (Kiya & Sasaki 1983, Kiya et al. 1984) in which time-averaged properties of the separation bubble are given in terms of the turbulence intensity at a reference point near an edge of the plate. The longitudinal and spanwise integral length scales of vortices in the separation bubble were given as functions of the free -stream turbulence intensity. The cross correlations between the surface-pressure and velocity fluctuations suggested that large-scale vortices are similar in shape independently of the free-stream turbulence intensity. Moreover, the maximum gradient of the time-mean surface-pressure profile and the longitudinal length scale of vortices in the reattaching zone.