Coolant Jets Interaction in Effusion Cooling System: Experimental and Numerical Study

Abstract

The interaction of coolant jets is significant in effusion settings as a result of the short streamwise and spanwise distance between films. This complicates the design of effusion cooling devices because computing the interaction between numerous, closely spaced rows of films is a challenging task. A flat plate effusion cooling model is investigated at both low and high blowing ratios. Pressure-sensitive paint (PSP) is used to measure film effectiveness. Computational fluid dynamics (CFD) calculations are performed to examine the cooling flow features in detail. The mesh sensitivity is studied to demonstrate the effect of mesh size on film effectiveness. The solution obtained by coarse mesh may not capture the correct trend with blowing ratio variation. Results of the computational work by fine mesh demonstrate good agreement with the measured effectiveness. Coolant jets interaction is also investigated. The profile of quantities such as velocity, temperature, kinetic energy, and Reynolds stress at several locations in the flow field is compared. The boundary layer profiles are scaled by the thermal boundary layer thickness to study the feature of heat transfer. It is observed that profiles of the flow quantities are self-similar. Two distinct scalings are found: an outer scaling based on boundary layer thickness which collapses the upper part of the profiles; an inner scaling which collapses the profiles at distances from the wall comparable to the penetration depth of a single jet. The latter scaling is based on the distance from the wall to the minimum temperature profile. This distance identifies the location of the coolant leaving the effusion cooling device.