Experimental and Numerical Impingement Heat Transfer in an Airfoil Leading-Edge Cooling Channel With Cross-Flow

Abstract

To enhance the internal heat transfer around the airfoil leading-edge area, a combination of rib-roughened cooling channels, film cooling, and impingement cooling is often employed. Experimental data for impingement on various leading-edge geometries are reported by these and other investigators. The effects of strong cross-flows on the leading—edge impingement heat transfer, however, have not been studied to that extent. This investigation dealt with impingement on the leading edge of an airfoil in the presence of cross-flows beyond the cross-flow created by the upstream jets (spent air). Measurements of heat transfer coefficients on the airfoil nose area as well as the pressure and suction side areas are reported. The tests were run for a range of axial to jet mass flow rates (Maxial∕Mjet) ranging from 1.14 to 6.4 and jet Reynolds numbers ranging from 8000 to 48,000. Comparisons are also made between the experimental results of impingement with and without the presence of cross-flow and between representative numerical and measured heat transfer results. It was concluded that (a) the presence of the external cross-flow reduces the impinging jet effectiveness both on the nose and sidewalls; (b) even for an axial to jet mass flow ratio as high as 5, the convective heat transfer coefficient produced by the axial channel flow was less than that of the impinging jet without the presence of the external cross-flow; and (c) the agreement between the numerical and experimental results was reasonable with an average difference ranging from −8% to −20%.