Conjugate Heat Transfer on the Effect of Impinging Distance for Film-Cooled Blade Leading Edge With Staggered-Oblique Impinging Jets

As turbine inlet temperature gradually increases, cooling demands on the blade leading edge become notably more pronounced. Staggered-oblique impingement scheme has been proved to be a favorable scheme for achieving great cooling performance while ensuring a uniform temperature distribution on the blade leading edge. Conjugate heat transfer simulations are conducted to investigate the effects of impinging distance on the flow structures and heat transfer characteristics of film-cooled blade leading edge with staggered-oblique impinging jets. Three different impinging distances (L/djet = 3, 4, 5) are discussed at jet Reynolds number of 6000, 12000, and 18000 using a validated SST k-ω turbulence model. Results indicate that Nusselt number and overall cooling effectiveness are enhanced by increasing jet Reynolds number. With an increasing impinging distance, the impingement stagnation point moves far away from the blade stagnation line, enlarging the influenced target area. However, this leads to a reduction in the area-averaged Nusselt number due to diminished wall jet momentum. As the impinging distance increases, there is a slight increase for the area-averaged overall cooling effectiveness on the concerning leading edge wall, while a decrease is observed in the mainstream stagnation region. Moreover, higher impinging distances contribute to improved temperature uniformity on the leading edge external wall. Consequently, the staggered-oblique impingement scheme with impinging distance of L/djet = 4 appears to be the most optimal choice.