A Study on the Effect of Angle in Diffused Hole Film Cooling Effectiveness at Different Blowing Ratios

Abstract

Higher the turbine inlet temperature of a gas turbine, higher will be the efficiency, however the increase in the turbine inlet temperature is limited to the materials and the cooling strategies employed. This article presents a study on the effect of blowing ratio on film cooling effectiveness for a cylindrical hole and a diffused hole at different angles. The analysis was done for blowing ratios of 0.5, 1.0, 1.5 and 2.0 while the angle in the diffused hole was varied as 5°, 10° and 15°. A grid independence study was performed and the simulation was validated. The results of cylindrical and different angles of diffused holes were compared. For a cylindrical hole as well as diffused hole, a blowing ratio of 1.0 was found to have an optimal effectiveness. The diffused hole was found to improve the near hole and downstream effectiveness at higher blowing ratios.

Numerical study of film cooling effectiveness of a gas turbine blade under variable blowing ratio and turbulence intensity

“…Most research has been done by the RANS approach with the k –$$\varepsilon $$ turbulence method to simulate the film cooling of the typical blades 12 . The main parameters involved in the film cooling phenomena (blowing ratio, turbulence intensity, hole angle, hole geometry, in stagger and in‐line hole arrangement, hole to hole distance, coolant velocity, and temperature) are examined in various studies 13–25 …”

“…By increasing the blowing ratio, the geometry hole with bean‐shaped has the best efficiency in film cooling. Gandhi and Sivan 18 numerically examine the different blowing ratio performances on the cylindrical and various angles of diffused holes. The author's results showed that diffused holes developed the film cooling performance near the injection hole in the low blowing ratio and downstream efficiency in the high blowing ratio.…”

“…12 The main parameters involved in the film cooling phenomena (blowing ratio, turbulence intensity, hole angle, hole geometry, in stagger and in-line hole arrangement, hole to hole distance, coolant velocity, and temperature) are examined in various studies. [13][14][15][16][17][18][19][20][21][22][23][24][25] Leylek et al [13][14][15][16] performed their studies in film cooling physics in four-part complement papers. In Part I, Walters and Leylek 13 analyzed the flow structures discover in film cooling holes and the area of the jet's interaction in the cross-flow.…”