Tip Clearance Flow-Shock Interaction in a Transonic Compressor Rotor

Abstract

A combination of experimental, computational, and analytical efforts were used to describe the phenomenological features of the interaction between the tip clearance e ow and the passage shock in a transonic, axial compressor rotor. Unsteady static pressure was measured at the casing over the rotor, and steady measurements of total pressure and total temperature were made at the rotor exit. A fully three-dimensional, steady, Navier ‐ Stokes computational e uid dynamics technique was used to obtain a solution to the e owe eld at design conditions that compared favorably with the experimental measurements. Finally, a simple model was developed that predicts the kinematic and thermodynamic properties within the pre- and postshock vortex. Analysis of the numerical results revealed a wake-like nature of the vortex both upstream and downstream of the shock. The upstream character was strongly ine uenced by the injection of mass into the vortex via the clearance e ow. The success of the simplie ed model’ s ability to predict the properties of the vortex within the interaction region allows two important conclusions to be drawn. First, the vortical character of the vortex upstream of the shock is not a signie cant factor in driving the interaction. Second, the interaction between the clearance e ow and the shock is fundamentally the result of the change in momentum brought about by the shock-induced pressure rise. The interaction can therefore be viewed as an inviscid phenomenon.