Numerical investigation on the effect of sealing clearance on endwall film cooling effectiveness under rotating condition

By using an integrated numerical model with disc cavity and turbine blade, the endwall film cooling effectiveness is investigated numerically in this paper. The numerical simulation is conducted by using the shear stress transfer model to solve the Reynolds-averaged Naiver Stokes equation. Carbon dioxide is chosen as the coolant to maintain the coolant-to-mainstream density ratio. The diffusion process of coolant is characterized by solving the turbulent transport equation. Effects of axial clearance (AC1 = -3mm, -1.5 mm, 0 mm, 1.5 mm, 3 mm) and radial clearance (SC1 = 0.8 mm, 1.2 mm, 1.6 mm, 2.0 mm, 2.4 mm) on the endwall film cooling effectiveness are investigated under different coolant-to-mainstream mass flow ratios (MFR = 0.5 %, 1.0 %, 1.5 %, 2.0 %, 2.5 %). Both MFR and sealing clearance can influence the endwall film cooling effectiveness. It is found that: (1) With increasing MFR, the endwall film cooling effectiveness is improved. (2) When MFR >= 1 %, the endwall film cooling effectiveness increases with increasing AC1 for lower circumferential velocity component of the leakage flow. (3) When MFR >= 1 %, the endwall film cooling effectiveness increases with increasing SC1 for more leakage flow flowing out from the cavity.