Numerical investigations on film cooling effectiveness and heat transfer performance of inclined film hole on the turbine blade squealer tip with plasma actuation

Abstract

The turbine blade tip frequently encounters elevated thermal loads, necessitating effective protection measures. Conventional film cooling techniques, while employed to mitigate erosion, face challenges in achieving optimal performance due to intricate tip leakage flow dynamics. Thus, the development of advanced film cooling methodologies becomes imperative to ensure the optimal operation of blade tips. In this study, a novel film cooling approach is proposed, leveraging a combination of dielectric barrier discharge (DBD) plasma actuators and inclined film holes. This strategy aims to direct cooling jets towards the tip wall surface, enhancing film cooling efficacy on highly-loaded turbine squealer tips. Numerical investigations are conducted to assess film cooling effectiveness, heat transfer coefficients, and coolant jet flow characteristics across varying actuation strengths (0, 0.6, 0.8, and 1.0) by integrating plasma actuation forces into the Reynolds-Averaged Navier-Stokes equations. Additionally, the impact of different blow ratios (0.5, 1.0, and 1.5) on plasma flow control is examined. Results demonstrate that plasma actuation improves film cooling performance and effectively mitigates tip heat transfer, even in the presence of interfering tip leakage flow. Specifically, at an actuation strength of 1.0, the average blade tip film cooling effectiveness increases by 7.1%, accompanied by a 12.3% reduction in average heat transfer coefficient compared to scenarios without plasma actuation. Furthermore, the blow ratio influences plasma actuation performance, with minimal disparity observed between configurations with and without plasma devices under extreme blow ratio conditions.