Rotational influences on aerodynamic and heat transfer behavior of gas turbine blade vortex cooling with bleed holes

Abstract

The suitable vortex chamber model with bleed holes is established to further investigate vortex cooling mechanism. Numerical simulations are performed by solving 3D steady Reynolds Averaged Navier-Stokes (RANS) equations and the k-ω turbulence model. Grid independence analysis is conducted to obtain the proper grid dimension. Effects of rotation number (Ro=0, 0.227, 0.464, 0.718, 1), rotating direction (Ro=−0.464, 0.464), density ratio (Δρ/ρ=0.2, 0.3, 0.4, 0.5) on flow and heat transfer behavior of vortex cooling with bleed holes are researched in detail. The rotation number is defined as Ro=ωDh/U, where ω, Dh and U represent the rotational angular velocity, chamber cross section hydraulic diameter and mean axial velocity. Results indicate that the existence of bleed holes can disturb vortex flow and enhance heat transfer intensity. Model rotation has obvious influences on flow and thermal performance of vortex cooling with bleed holes. As the rotation number increases from 0 to 1, the air rotational flow velocity and static pressure decrease, thus leading to decreasing heat transfer intensity by 19.2%. Compared with Ro=−0.464, higher rotational velocity flow and lower inlet static pressure exist at Ro=0.464, hence the heat transfer intensity is higher and shows more uniform. The cooling air rotational flow in the vortex chamber is almost independent of density ratio. The vortex heat transfer intensity will increase by 29.6% with the increasing density ratio from 0.2 to 0.5.