Study of flow and heat transfer for pulsating film cooling by dynamic modal decomposition

Abstract

The effect of pulsating jet on the unsteady film cooling performance was studied by experimental and numerical simulation. The FLIR thermal infrared thermal camera was used the measure the adiabatic temperature of the surface. The large eddy simulation was conducted for analyzing the adiabatic film cooling effectiveness at four different jet non-dimensionalized pulsated frequency of St = 0, 0.1, 0.2, and 0.3. The analysis of the dynamic model decomposition of both the velocity and temperature fields obtained by numerical calculation was performed to obtain the coupling relationship between the flow and heat transfer. Results show that the cooling effectiveness of steady film cooling (St = 0) decreases with the increase of blowing ratio. At low blowing ratio (M = 0.65), the cooling efficiency of the pulsating jet is significantly lower than the steady-state jet. At the blowing ratio of 1.0 and 1.5, the cooling efficiency of the low frequency pulsating jet (St = 0.1) is a little higher than the steady-state jet, indicating that the low frequency pulsation under the high blowing ratio can improve the coverage of the cooling air. At high pulsating frequency (St = 0.3), the cooling effectiveness is obviously declined.