Parallel plate combustor wall cooling was investigated. The combustor air flowed down the gap between two flat surfaces in a low pressure loss configuration. The work was aimed at combustor liner external air cooling for regenerative combustor cooling prior to entering a lean low NOx combustor. The test rig was 152 mm square and the test section was a duct of 152mm width and height of 10 and 5mm with a 152mm length. The experimental investigation involved the measurement of the heat transfer coefficient using the lumped capacity method. together with overall wall cooling effectiveness measurements in a hot duct test rig. The compromise between increased pressure loss and enhanced heat transfer for obstacles in the duct was investigated. It was shown that at coolant flow rates comparable with combustor requirements, adequate wall cooling effectiveness could be achieved using this technique. The cooling effectiveness performance was compared with the alternative technique of impingement cooling using low impingement jet pressure loss

This paper presents computational predictions of adiabatic film cooling effectiveness for effusion cooling systems with 90o and 30o holes. Predictions are performed for a range of coolant injection mass flow rates per unit surface area, G, of 0.1kg/sm2 - 1.6 kg/sm2 for 90o holes with constant pitch-todiameter ratio of X/D = 11 and 10 rows of holes and for 30o inclined holes with X/D = 11 and 15 rows of holes over a 152mm surface length. The computational works performed are steady-state and the turbulent governing equations are solved by a control-volume-based finite difference method with second-order upwind scheme and the k-epsilon turbulence model. The velocity and pressure terms of momentum equations are solved by the SIMPLE method. The CFD prediction were validated by comparing the predictions with literature data for single rows of inclined holes and then applied to effusion cooling. The predictions included the use of a tracer gas in the coolant, which was used to predict the mixing of the coolant with the hot mainstream gases. Also the surface distribution of the tracer gas was a direct prediction of the cooling effectiveness. The mixing of coolant with the mainstream was studied and boundary layer temperature and coolant mixing profiles were predicted. These were compared with temperature measurement in a hot effusion cooling test rig.