Turbine Tip and Shroud Heat Transfer and Loading—Part A: Parameter Effects Including Reynolds Number, Pressure Ratio, and Gas-to-Metal Temperature Ratio

Abstract

Turbine tip and shroud flow and heat transfer are some of the most complex, yet important, issues in turbine design. Most of the work performed to date has been performed in linear cascades and has investigated such items as the effect of tip geometries and turbulence on tip and shroud pressure and heat transfer. There have been very few full annulus or rotating measurements in the literature. Experimental measurements have been made on a single stage high pressure turbine at the US Air Force Turbine Research Facility (TRF) to aid in the understanding of this phenomena. The TRF is a full scale, rotating rig that operates at matched flow conditions to the true turbine environment. Heat flux measurements were acquired with both Pyrex insert strip and button gages, while the pressure measurements were taken with surface-mounted Kulite® pressure transducers. This paper presents one of the first full rotating, simultaneous pressure and heat transfer measurements to be taken in the turbine tip shroud region. These measurements provide some of the details needed for accurately quantifying the true flow condition in this complex flow regime. Comparisons between the present data and the existing 2-D cascade data were made. This investigation quantified the effects of Reynolds number, inlet temperature, turbine pressure ratio and inlet flow temperature profiles. This provides a benchmark data set for validation of numerical codes.