Experimental Studies of Effusion Cooling

Abstract: The desire to increase the efficiency of jet engines, has led to an increase in the temperature in the combustion chambers and in the turbine stage. There is thus an interest in efficient cooling methods. Film cooling and effusion cooling are often used where there is a great heat load.

A parametric study of surface temperature distributions on effusion cooled plates was done by means of infrared thermography. The effects of different temperature ratios, velocity ratios, Reynolds numbers, hole spacings, injection angles and thermal heat conductivity of the wall material were investigated. The experiment was designed to scale with a combustion chamber condition of a real gas turbine. The results show how the different parameters act and their relative importance. It is intended that the results of this study will be helpful in finding a design in which it is ascertained that the wall temperature is kept below a certain value.

A complete mapping of the 3D velocity field and turbulence fields near one of the injection holes in the third row of holes was made using three-component laser-Doppler anemometry. In this case, T_jet /T_c=1, Re_d=5800, U_jet /U0=0.89 and the jet was injected at an angle of 30° to the crossflow. The three velocity components and the complete turbulent stress tensor have been measured in 35340 points around and behind the jet. A topological map of the flow field is presented, and the vorticity field and pressure field are discussed. The different terms in the production of the Reynolds stresses are presented.