A Trace Gas Technique to Study Mixing in a Turbine Stage

Abstract

An experimental technique to study mixing in a turbine stage is demonstrated. An axisymmetric, radial temperature profile at the inlet to the first stator of a large-scale, low-speed, single-stage, axial flow turbine model is simulated with a radial trace gas concentration distribution. Mixing or redistribution of the inlet profile by three-dimensional aerodynamic mechanisms (other than temperature-driven mechanisms) is determined from trace gas concentration measurements made in both the stationary and rotating frames of reference at various locations through the turbine. The trace gas concentration contours generated are consistent with flow pitch angle measurements made downstream of the first stator and with surface flow visualization on the rotor airfoil and the hub endwall. It is demonstrated that this trace gas technique is well suited to quantify many aspects of the redistribution and diffusion of an inlet temperature profile as it is convected through a turbine stage.