EFFECT OF COOLANT TEMPERATURE AND MASS-FLOW ON FILM-COOLING OF TURBINE-BLADES

A three-dimensional Navier-Stokes code has been used to study the effe ct of coolant temperature, and coolant to mainstream mass flow ratio o n the adiabatic effectiveness of a film-cooled turbine blade. The blad e chosen is the VKI rotor with six rows of cooling holes including thr ee rows on the shower head. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900K and stagnation p ressure = 3 MPa. Generally, the adiabatic effectiveness is lower for a higher coolant temperature due to nonlinear effects via the compressi bility of air. However, over the suction side of shower-head holes, th e effectiveness is higher for a higher coolant temperature than that f or a lower coolant temperature when the coolant to mainstream mass flo w ratio is 5% or more. For a fixed coolant temperature, the effectiven ess passes through a minima on the suction side of shower-head holes a s the coolant to mainstream mass flow ratio increases, while on the pr essure side of shower-head holes, the effectiveness decreases with inc rease in coolant mass flow due to coolant jet lift-off. In all cases, the adiabatic effectiveness is highly three-dimensional. Copyright (C) 1996 Elsevier Science Ltd.