TIP CLEARANCE FLOW-SHOCK INTERACTION IN A TRANSONIC COMPRESSOR ROTOR

A combination of experimental, computational, and analytical efforts w ere used to describe the phenomenological features of the interaction between the tip clearance now and the passage shock in a transonic, ax ial compressor rotor, Unsteady static pressure was measured at the cas ing over the rotor, and steady measurements of total pressure and tota l temperature were made at the rotor exit, A fully three-dimensional, steady, Navier-Stokes computational fluid dynamics technique was used to obtain a solution to the flowfield at design conditions that compar ed favorably with the experimental measurements. Finally, a simple mod el was developed that predicts the kinematic and thermodynamic propert ies within the pre- and postshock vortex, Analysis of the numerical re sults revealed a wake-like nature of the vortex both upstream and down stream of the shock, The upstream character was strongly influenced by the injection of mass into the vortex via the clearance how The succe ss of the simplified 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 t he shock is not a significant factor in driving the interaction, Secon d, the interaction between the clearance now and the shock Is fundamen tally the result of the change in momentum brought about by the shock- induced pressure rise, The interaction can therefore be viewed as an i nviscid phenomenon.