Evaluating the heat transfer characteristics of mesh-fed slot cooling configuration: Influence of slot height and pin-fin arrangement

Abstract

Understanding the performance of cooling structures under different parameters can provide more effective thermal protection for turbine blades. To better understand how the slot height and in-wall pin–fin arrangement affect heat transfer in slot structures, both experimental and numerical methods were utilized. The adiabatic cooling effectiveness η and heat transfer coefficient (HTC) distribution on the slot-downstream surface were measured via transient thermochromic liquid crystal (TLC) technology to analyse the effects of the slot height and in-wall pin–fin arrangement on the film cooling characteristics of a mesh-fed slot configuration. The blowing ratio M ranged from 0.26 to 1.25. The results indicated that the η of the mesh-fed slot configuration did not exhibit jet lift-off from the wall as M increased. Owing to the influence of the pin-fins and the inclined surface downstream of the slot, counter-rotating vortices formed downstream of the slot, resulting in a relatively high η downstream of the end row of pin-fins. At a low M of 0.26, the laterally averaged HTC ratio for the configuration with a 3 mm slot height was higher than that of the case with a 5 mm slot height in a staggered pin–fin arrangement. However, this trend was reversed as M increased. Under the in-line pin–fin arrangement, the η distribution downstream of the slot was more uniform, and at a high M, the laterally averaged η was 23 %∼84 % greater than that of the staggered arrangement, with the HTC ratio being 11 % greater. When M was less than 1, the discharge coefficient C_d of the in-line arrangement was greater, whereas when M was greater than 1, the staggered arrangement demonstrated superiority.