Effects of soot deposition and slot erosion on the mist film-cooling of a flat plate in the presence of upstream ramp

Abstract

In the present work, the numerical analysis is conducted on the film cooling of a flat plate with the air and mist injection from a slot. The effect of soot deposition and erosion of the cooling slot has been investigated in the presence of an upstream ramp. Simulations are performed at blowing ratios, M = 1, 1.5 and 2 with the slot angles, θ = 30°, 45° and 60°. The effect of presence of upstream ramp is studied by varying ramp angles from α = 5° to 15°. The numerical study is carried out on Eulerian-Eulerian framework. Thermal phase change model based on the evaporation and condensation is used to account heat and mass transfer. It is found that the film cooling effectiveness is better for the mist injection as compared to the air injection. Soot deposition on the cooling slot has a significant influence on the film cooling effectiveness. The soot deposition is not always adversely affecting the film cooling effectiveness. Moreover, the film cooling effectiveness decreases for the eroded slot for all the investigated slot angles and ramp angles for mist injection. An increment in the film cooling effectiveness is observed for 0 < x/2w < 15 in the presence of the upstream ramp; thereafter film cooling decreases as compared to the case without the upstream ramp. The optimum slot angle to inject the mist is found to be θ = 45°.