A New Perspective on Internal Turbine Blade Cooling by Perforated Blockages and Pin-Fins

Abstract

The cooling configuration, sequentially combining perforated blockages (forming blockage jets) and a pin-fin array inside the trailing-edge of a turbine blade has been perceived unsuitable due to the presumed inferior thermal performance (η < 1.0). In the present study, we provide a new perspective on this particular cooling configuration, based on fluidic mechanisms, newly established in a better representative setup for blockage jets aligned with pin-fins, accounting for relevant heat transfer surfaces. To this end, heat transfer on the blockage, pin-fin, and end-wall surfaces was measured at a selected Reynolds number of ReD = 26,000 using a thermochromic liquid crystal technique. Flow field mapping by particle image velocimetry and oil–dye flow visualization were supplementally performed. We demonstrate, contrary to previous studies that the thermal performance of the blockage pin-fin configuration can be e.g., η = 1.1 if the blockages and pin-fins are arranged to maximize both elements' thermofluidic advantages. Our data further suggest that unlike conventional pin-fin configurations subjected to uniform coolant stream, the blockage pin-fin configuration can offer a better performance with fewer pin-fin rows used.