Effects of Mainstream Velocity and Turbulence Intensity on the Sweeping Jet and Film Composite Cooling

Abstract

The jet always sweeps to the leftmost and rightmost points in the sweeping jet and film composite cooling (SJF) process, resulting in a different coolant flow in each film hole. The film can not easily cover the outer surface evenly under the scouring of the mainstream. This work presents a case study to analyze the effects of two mainstream variables on the film areodynamic and cooling performance of the SJF. Three different mainstream velocities (Vm= 10 m/s, 50 m/s, 90 m/s) and three different mainstream turbulence intensities (Tu = 1%, 10%, 20%) are discussed. Results indicate that the increase of mainstream velocity yields to better film attachment. When the mainstream velocity increases from 10 m/s to 50 m/s, the overall cooling effectiveness and total pressure loss coefficient are reduced by 17.68% and 98.60%, respectively. When the mainstream velocity increases from 50 m/s to 90 m/s, the overall cooling effectiveness and total pressure loss coefficient are almost unchanged. The effect of turbulence intensity on the overall cooling effectiveness and total pressure loss coefficient are relatively small. The increase of mainstream turbulence intensity enhances the disturbance of the mainstream to the coolant from the middle film holes, and the distribution of adiabatic film cooling effectiveness is more uneven when the mainstream turbulence intensity is raised to 10% and 20%. In the research scope of present work, the flow structure, total pressure loss coefficient and overall cooling effectiveness are the most expected under the conditions of lower turbulence intensity and higher mainstream velocity (Tu = 1%, Vm= 90 m/s).