The momentum transfer of incompressible turbulent separated flow due to cavities with steps

Abstract

An experimental study was conducted using a plate test bed having a turbulent boundary layer to determine the momentum transfer to the faces of step/cavity excrecences on the plate. Tested configurations include an isolated excrecence and an array of blocks in tile patterns. A momentum transfer correlation model of pressure forces on an isolated step/cavity was developed with experimental results to relate flow and geometry parameters. Results of the experiments reveal that isolated step/cavity excrecences do not have a unique and unifying parameter group due in part to cavity depth effects and in part to width parameter scale effects. Drag predictions for tile patterns by a kinetic pressure empirical method predict experimental results w ell. Trends were not, however, predicted by a method of variable roughness density phenomenology. Data presented will be helpful in testing formal numerical solutions over a step/cavity excrecence, and correlations permit drag predictions on like configurations.