Film Cooling Effectiveness Downstream of Trailing Edge Slots Including Cutback Surface Protuberances

Abstract

The trailing edge of the high pressure turbine blade and vane presents significant challenges to the turbine cooling engineer. The current research has focused specifically on the effect of cutback surface protuberance, or "land", shapes on film cooling effectiveness. A set of six different land geometries has been investigated in a large scale model of the trailing edge pressure side ejection slot exit. Slot height and width and lip height was maintained. Pressure sensitive paint was used to measure adiabatic film cooling effectiveness at five blowing ratios ranging from 0.6 to 1.4 in increments of 0.2. High-resolution full surface distributions of film cooling effectiveness both on the cutback surface and the top of the lands were recorded. It was found that tapering the lands did not significantly increase effectiveness on the lands and slightly reduced effectiveness near the lands. Using a diffuser shape improved average effectiveness greatly and gave the best overall performance up to the end of the lands except at the lowest blowing ratio of 0.6, where having no lands was slightly better.

Assessment of binary PSP technique for film cooling effectiveness measurement on nozzle vane cascade with cutback trailing edge

“…Shifting attention to the cutback region, the comparison is made with literature data coming both from simplified models without mainstream acceleration [11,30] and cascade data [31]. Martini et al [30] and Dannhauer [31] configurations have internal ribs that do not extend outside the slot; in both cases IR thermometry was used to measure the film cooling effectiveness distribution.…”

“…Natsui et al [10] performed a detailed analysis of the influence of experimental aspects like test repeatability that might impact on the uncertainty of film cooling effectiveness values taken by using PSP technique, providing recommendations for testing methodologies able to minimize sources of potential errors. PSP technique has been also used in simplified models of trailing edge cooling slots [11][12], allowing to investigate the influence of slot internal geometry on the thermal protection of the cutback surface.…”

Multi-objective optimization of three rows of film cooling holes by genetic algorithm

“…The relationship between the objective functions and design variables are obtained by using Curve fitting. This method (CFM) is usually applied for analyzing the results of numerical and experimental studies in film cooling technique [28][29][30][31]. The optimum design point can be detected by the following curve fittings equations:…”

Film Cooling Effectiveness Downstream of Optimised Cross Corrugated Slot Geometry with Exit Shaping

“…Yang and Hu (2012) used stereoscopic particle image velocimetry to take flow field measurements of an interrupted slot geometry with and without lands and compared these with film cooling effectiveness maps acquired using the pressure sensitive paint (PSP) technique (Yang and Hu, 2011). The PSP technique was used in a previous study (Wong et al, 2016a) to measure effectiveness on top of the lands with different land geometries. This was taken further by Gurram et al (2016) using PSP on a full blade profile at engine Mach numbers.…”