Modelling of three-dimensional jet array impingement and heat transfer on a concave surface

The paper reports computations of the flow and heat-transfer from a row of round jets impinging onto a concave semi-circular surface, designed to reproduce important flow features found in internal turbine blade cooling applications. Linear and non-linear eddy-viscosity models are applied, with wall-functions to cover the near-wall layer. These are shown to capture the overall flow characteristics, including the wall jets created by impingement on the curved surface and the downwashes caused by the collision of these wall jets. Whilst the non-linear model performs slightly better than the linear, both underpredict the turbulence levels close to impingement and in the downwashes. andard, log-law based, form of wall-function is found to be inadequate in predicting the heat-transfer, and a more advanced form developed at Manchester (the AWF) is also tested. The exact way in which convective terms are approximated in this latter approach is shown to be crucial, and a form is presented which leads to stable and reasonably accurate solutions that capture the overall pattern and impingement Nusselt number levels shown in measurements, but underpredict heat transfer levels around the jet downwashes.