Full coverage impingement heat transfer: Cooling effectiveness

Abstract

Cooling effectiveness data are presented for impingement cooled surfaces with no film cooling and the results are directly compared with both effusion film and combined impingement/effusion cooling. The aim was to evaluate the potential of optimised impingement cooling designs to adequately cool combustor wall and turbine blade surfaces. Specific designs relevant to a combustor wall cooling application were investigated, and in particular the situation where all the combustor air flow was used for wall cooling prior to combustion. This requires the impingement pressure loss to be minimised so that an adequate pressure loss remains for the combustion process. Consequently, the impingement plate pressure loss or X/D was the major parameter investigated for a fixed number of holes of 4306/m. It was shown that a nigh cooling effectiveness was achieved with a low pressure loss, thus establishing total impingement cooled combustors as a viable design possibly removing any requirement for the present large combustor film cooling flows.