Effect of Rotation on Heat Transfer and Flow Field Inside Leading Edge Cooling Passage Using Impinging Jets

Abstract

In this paper, the effect of rotation on impingement cooling on the internal surface (profile) of the leading edge region in a turbine rotor blade is investigated using Computational Fluid Dynamics (CFD) simulations. The flow domain is obtained by stretching the middle cross section of the blade. The simulations are performed for 3 different leading edge profiles to increase the heat transfer rate in the cooling flow passage in stationary domain. In all the profiles, the nozzle position and Mach number of cooling fluid is kept constant at E/D=4.32 and 0.4 respectively. In the profile 1, the suction side profile is modified to facilitate vortex shift so that it may reduce the crossflow effect which will enhance the Nu avg . But Nu avg reduced by 1.9% when compared to base case. In the profile 2, the coolant flow passage is smoothened at the apex to reduce dead zones and to enhance spreading of the jet. In this case, a 3.48% increase in Nu avg is obtained. Based on the analysis of velocity contours in the profile 2, the leading edge profile is further modified (profile 3). This resulted in 5.37% increase in the Nu avg. The effect of rotation on the Nu avg for different Mach numbers (M) in the profile 3 and base case are studied. When compared to stationary domain Nu avg is reduced for base case and profile 3. In rotating domain profile 3 shows improvement for different M when compared with base case. For M= 0.2, the Nu avg is increased by 2.7%, for M=0.4, Nu avg is increased by 3.98% and for M=0.6, it is negligible.