Optimization Based on Boundary Layer Concept for Compressible Flows

A dissipation integral boundary layer method is briefly presented which serves as the basis of the optimization. The principles of optimum deceleration are explained. Following these principles the optimum boundary layer development is specified and the velocity distribution follows from the boundary layer equation. The corresponding shape is obtained from a potential method. It is found that the straight channel and conical diffusers do have a boundary layer development close to the optimum one and it is not worth to improve their performances by wall shaping. Two conical diffusers at high inlet Mach number are anaylzed and the predictions agree satisfactorily with the experiment.