Prediction of fluctuating pressure in attached and separated turbulent boundary-layer flow

Abstract

A methodology is presented that predicts the fluctuating pressure and power spectra for attached zeropressure gradient and separated turbulent boundary-layer flow on smooth and rough surfaces. Attached flow conditions use a prediction technique that employs a transformation of boundary-layer properties from the compressible to the incompressible plane where a comparison can be made to an extensive data base. For a rough wall, it is shown that the rms pressure, which scales with wall shear, can be predicted by augmenting the smooth wall value by the rough/smooth skin-friction ratio. Relative to nonattached flow, represented by two-dimensional compression corner and three-dimensional fin-generated shock/boundary-layer interactions, the rms pressure is shown to scale with approach flow conditions and the oblique shock in viscid pressure rise. For this situation, a new in viscid angle has been defined as = a + /3 sin^U/M) where a is the shock generator angle and /3 is a parameter based on two-dimensional or three-dimensional interactions. Both rms pressure and power spectra have been correlated in terms of undisturbed approach flow boundary-layer parameters and modified inviscid shock strength relations to provide engineering solutions for the design resolution to complex flow problems.