Similarities of pressure induced by separation bubble in grid-generated turbulent flow

Some existing wind-tunnel data on mean pressure and fluctuation pressure distributions, induced by a separation bubble near the leading edge of a blunt plate, in the presence of grid-generated freestream turbulence, are systematically analyzed in this paper. The mean pressure distributions, when expressed in reduced coordinates, are self-similar and may be approximated by the pressure variation induced by an inviscid rotational vortex hovering above a flat surface in uniform smooth flow. These coordinates are expressed in terms of characteristic parameters of the mean flow field and each parameter has been correlated with the longitudinal component of the turbulence intensity and scale non-dimensioned by the plate thickness. In analyzing the pressure fluctuation, a similar approach is used. The results from the rotational vortex are consistently useful when considering the leading portion of the bubble characterized by the location of maximum fluctuation. The remaining portion may be represented by an exponential function characterized by the turbulence intensity only. The outcome of this study may be used as a prediction method whose validity has been checked with experimental data.