Heat transfer enhancement of return channel by using rib turbulator for a new impingement cooling scheme

Abstract

Impingement cooling method is widely applied to leading edge of turbine blade to ease thermal load. However, spent jet always develops into crossflow, which weakens cooling efficiency by deflecting the impingement direction of jet. An innovative impingement cooling structure can suppress the crossflow effect by drawing spent jet into return channel through return holes. This study further improves the heat transfer capability of the structure by introducing ribbed sidewall to the return channel. The effects of rib arrangements are investigated as the Reynolds number increases from 5000 to 15,000. The flow field and the heat transfer performance of the structure are analyzed numerically. The BSL turbulence model is utilized to conduct the simulation. The numerical results indicate that the ribs have a positive effect on improving heat transfer performance. The ribs disturbs the original flow in the return channel and increase the total pressure loss. The average Nusselt number on the sidewall of the return channel in the case with the optimal rib arrangement in this study is increased by 5.4% ∼ 10.4% compared to baseline value as the jet Reynolds number rises.