Introduction between an oblique shock wave and a subsonic stator cascade (contribution to the study of unsteady wave propagation in a supersonic compressor stage)

A theoretical and experimental study is presented of the interaction between a uniform oblique shock wave and a subsonic vanes cascade, and allowing the estimation of the main consequences in a complete stage. The pressure and velocity fields surrounding an isolated idealized vane are determined theoretically by using the pseudostationary character of the waves' deformation around each extremity of the vane. The importance of the cascade effect is evaluated. An experimental investigation, with schlieren photographs taken in the shock tube, illustrates successively the interaction between an oblique shock and (1) a vane without flow, (2) a vane with subsonic flow, (3) a stator cascade with subsonic flow. The oblique shock and the flow are generated by the same relatively strong shock wave which is partly reflected on an oblique porous wall. The agreement with the theory is good and it is shown that a shock wave through a cascade is, in general, schematically divided into two main wave fronts connected by auxiliary waves.