Experimental investigation of turbulent separatedreattachment flow by using LDV
Abstract
A turbulent separationreattachment flow in a twodimensional asymmetrical curvedwall diffuser was surveyed with a twodimensional laser doppler velocimeter. The turbulent boundary layer was separated on the lower curved wall under strong pressure gradient and then reattached subsequently on a parallel channel. At the inlet of the diffuser, the Reynolds number based on the diffuser height is 1.2 x 10(exp 5) and the velocity is 25.2 m/s. The results of the experiments in newly defined streamlinealigned coordinates are presented and analyzed. The experiment showed that after Transitory Detachment there was a second extremum of normal Reynolds stress and shear stress appeared as a minus in the nearwall backflow region. A scale was formed using the maximum Reynolds shear stress. It was found that Reynolds shear stress similarity exists from separation to reattachment and the SchofieldPerry velocity law exists in the forward shear flow. Both profiles were used in the experimental work that led to the design of a new eddyviscosity model. The length scale came from that developed by Schofield and Perry. the composite velocity scale was formed by the maximum Reynolds shear stress and SchofieldPerry velocity scale as well as the edge velocity of the boundary layer. The results of these experiments are presented in this paper.
 Publication:

Joint Proceedings on Aeronautics and Astronautics (JPAA)
 Pub Date:
 May 1993
 Bibcode:
 1993jpaa.proc...23Y
 Keywords:

 Coordinates;
 Eddy Viscosity;
 Laser Doppler Velocimeters;
 Pressure Gradients;
 Separated Flow;
 Shear Stress;
 Turbulent Boundary Layer;
 Turbulent Flow;
 Asymmetry;
 Boundary Layer Flow;
 Extremum Values;
 Reynolds Number;
 Shear Flow;
 Wall Pressure;
 Fluid Mechanics and Heat Transfer