EXPERIMENTAL TURBINE AERO-HEAT TRANSFER STUDIES IN ROTATING RESEARCH FACILITIES

Abstract

The present paper deals with the experimental aero-heat transfer studies performed in rotating turbine research facilities. Turbine heat transfer research had significant progress in the last few decades. Since the full-scale operational conditions of a modern gas turbine dictate high temperatures well in excess of 3600 o F and pressure ratios ranging from 20 to 50, experimental forced convection heat transfer research on the gas side of a rotating turbine environment is a technically challenging task. The current paper provides a limited review of turbine heat transfer research in various facilities including short-duration blow-down and large-scale/low-speed turbine systems. Since the final status of any forced convection heat transfer problem is closely related to the detailed structure of momentum transfer in highly 3D, unsteady, rotating, and turbulent viscous flow environment, emphasis will also be placed on pertinent turbine aerodynamic features existing in turbines. The most significant parameters to simulate in a rotating aero-heat transfer facility can be listed as Reynolds number based on the blade chord, Mach number for compressibility and shock wave effects, tip speed, intensity and scale of free-stream turbulence, Strouhal number for the unsteady wake passing effects, free-stream to wall temperature ratio, coolant to free-stream temperature ratio, specific heat ratio, molecular Prandtl number of the operating gas and a rotation number for turbine aero heat transfer work performed under rotational conditions. A flow coefficient and a loading coefficient defined by the actual turbine hardware is typically maintained during laboratory testing.