A Transient Method Using Liquid Crystal for Film Cooling Over a Convex surface

Abstract

In order to explore the effect of blowing ratio on film cooling over a convex surface, the present study adopts the transient liquid crystal thermography for the film cooling measurement on a straight circular hole configuration. The test piece has a strength of curvature (2r/D) of 92.5, pitch to diameter ratio (P/D) of 3 and streamwise injection angle (γ) of 35∘ All measurements were conducted under the mainstream Reynolds number (Red) of 1700 with turbulence intensity (Tu) of 3.8%, and the density ratio between coolant and mainstream (ρc/ρm) is 0.98. In current study, the effect of blowing ratio (M) on film cooling performance is investigated by varying the range of blowing ratio from 0.5 to 2.0. Two transient tests of different injection flow temperature were conducted to obtain both detailed heat transfer coefficient and film cooling effectiveness distributions of measured region. The present measured results show that both the spanwise averaged heat transfer coefficient and film cooling effectiveness increase with decreased blowing ratio.

Keywords

• Convex surface
• Film cooling
• Liquid crystal thermography.