Experimental Measurement of Nusselt Number Correlations on Flat Plate and NACA 0010 Section Surfaces

This paper presents forced convection studies on a flat plate and NACA 0010 section airfoil surfaces. The surface temperatures of the models at given stations are measured with K-type thermocouples and used to assess the heat transfer characteristics of the models. The model surfaces are subjected to constant heat fluxes of 1.45kW/m² (for the flat plate) and 0.60kW/m² (for the airfoil) using KH Kapton flexible heaters. The temperature readings are then utilized to determine the heat transfer coefficients on the surfaces over a range of Reynolds numbers, from which Nusselt number correlations are deduced. The experiments were conducted in an open circuit wind tunnel, powered by a 37 kW motor, capable of generating air velocities of up to about 41 m/s in the 24 square-inch test section. For the flat plate, the Nusselt number correlations obtained agree well with what is reported in literature. The plate length (0.25m) used for the experiment was just enough for the initiation of turbulent thermal boundary layer at 35.60 m/s air speed. The flow phenomena and Nusselt number correlations on the NACA 0010 airfoil surface are also evaluated and found to fit correlations similar to that of a cylinder in cross flow for laminar case. However, turbulence on the airfoil surface has a significant influence on the average Nusselt number relation. Correlations for the laminar and turbulent flow regimes have been presented using a modified Hilpert and Churchill correlation for a cylinder in crossflow.