Convective Heat Transfer from a NACA Airfoil at Varying Angles of Attack

Abstract

Airfoil icing in aircraft and wind turbine applications has an adverse impact on aerodynamic performance, controllability, and system efficiency. A detailed understanding of convective heat transfer from airfoils is critical in the development of effective de-icing methods. In this paper, experimental correlations of heat transfer at different angles of attack of a NACA 63-421 airfoil are developed. Various angles of attack between 0 to 25 deg are investigated at different Reynolds numbers. The experimental data are correlated with respect to the Nusselt and Reynolds numbers, through a modified Hilpert correlation with an angular dependence on angles of attack. Conduction within the airfoil is balanced against heat transfer by convection from the airfoil surface in steady-state conditions. Both average and spatial variations of the heat transfer coefficients are nondimensionalized, through modifications of a Hilpert correlation for cylinders in crossflow. It is shown that the functional form of the Hilpert equation can effectively correlate the measured data for the NACA airfoil over a range of Reynolds numbers and angles of attack.