Quasi-Three-Dimensional Characteristics Method for a Supersonic Compressor Rotor

A new quasi-3D characteristics method has been developed to calculate the supersonic flow in a compressor rotor on an axisymmetric stream surface with variable radius and stream tube thickness. The method is valid for supersonic inlet flow with an attached shock wave at the blade leading edge where the inlet Mach number and flow angle are related by the unique incidence condition. On the basis of the quasi-3D characteristics method, a simple quasi-3D method has also been derived that calculates the unique incidence condition and the Mach number distribution on the suction side of the profile for a given stream surface and stream tube thickness. The reliability of the simple method is established by comparing results with those obtained by Denton’s time-marching method as well as those from the quasi-3D characteristics method. Systematic calculations performed using the simple quasi-3D method show the effects of varying the geometrical parameters of the cascade for different stream tube thickness and stream surface radius evolutions through the rotor.