Aerodynamic Loss in a Linear Turbine Cascade with Tip Clearance and Upstream Casing Coolant Injection

Abstract

This study describes the effect of casing coolant injection on aerodynamic loss in a linear turbine cascade with tip clearance. Four test cases with and without tip clearance and casing coolant injection are compared for this study. The mass flow rate and the non-dimensional swirl of the coolant are 0.5% of the main flow and 100% of the blade tip velocity respectively. Regardless of the presence of the tip clearance, casing coolant injection increases losses associated with the passage vortex and the trailing shed vortex and move their spanwise locations toward midspan. The loss near the casing without tip clearance increases significantly with casing coolant injection. However, in the casing with tip clearance, the loss near the casing is slightly decreased by the casing coolant injection. With casing coolant injection, tip clearance flow is reduced, and the loss associated with the tip clearance vortex decreases. Without tip clearance, the mass-averaged loss increases by 53.9% with casing coolant injection. However, with tip clearance, the loss increases by 15.9%.