Effect of Asymmetric Heating on Local Heat Transfer Distributions in a Pin Fin Channel

Abstract

High performance gas turbines require an efficient blade cooling system to allow for high rotor inlet temperatures. This work focuses on the pin fin cooling technique, where short pin fins are used to enhance the heat transfer rates by increasing the level of turbulence in the trailing edge of the blade. Experimental investigations are performed using infrared thermal imaging to determine local Nusselt number distributions in a staggered pin fin array. The pins have streamwise pitch-to-diameter ( XS/D) and spanwise pitch-to-diameter ( XT/D) ratios of 2 with a pin height-to-diameter ( H/D) ratio of 2. Both one wall and two wall heating cases are carried out using a constant heat flux boundary condition. It is found that the local Nusselt numbers are highest below the horseshoe vortices just upstream of the individual pin fins. The Nusselt numbers for the two wall heating case are observed to be 15-20% higher than those of the one wall case.