Investigation on the Blade Leading-Edge Film Cooling With Normal and Staggered-Oblique Impinging Jets

Abstract Film cooling is widely employed to protect the external wall of the turbine blade leading edge from hot gas exposure, while impingement cooling is a common internal cooling technique. This article experimentally investigates the effects of normal and novel impinging jets on film cooling effectiveness on the turbine blade leading edge using pressure-sensitive paint (PSP) measurements. Six models were studied, including cylindrical and laidback holes under different impingement conditions: without jets, with normal jets, and with staggered-oblique jets. Experiments were conducted at a mainstream Reynolds number of 3.25×105. Four blowing ratios of 0.75, 1.0, 1.5, and 2.25 were tested at a density ratio of 1.0. The results showed that impinging jets enhanced the uniformity of film cooling effectiveness. For cylindrical holes, impinging jets significantly increased area-averaged effectiveness on both the suction and pressure sides. In contrast, for laidback holes, the impact was more pronounced on the suction side. In the stagnation region, the type of film hole predominantly determined cooling performance. Among all configurations, the laidback hole structure with staggered-oblique impinging jets achieved the best cooling performance and stability. Furthermore, impinging jets improved the discharge coefficient for both types of film holes, with normal jets producing a greater enhancement than staggered-oblique jets. These findings provide valuable insights for optimizing the design of the impingement-film combined cooling structure on the blade leading edge to enhance cooling performance and stability.