Effect of square dimples on the temperature distribution and heat transfer coefficient of an NACA0012 airfoil

Abstract

ABSTRACTThe thermal boundary layer is the barrier for convective heat transfer, since the temperature within the thermal boundary layer is lower than the free stream temperature; therefore, it is preferable to maintain a small thermal boundary layer thickness (δt). Among the various categories of dimples like square, rectangle and triangle we considered square dimples for the upper surface of the NACA0012 wing throughout the span. The dimples increase the coefficient of lift due to delayed flow separation. The skin friction coefficient improvement reduces the δh which in turn reduces the (δt), therefore the rate of heat transfer is increased and surface temperature distribution becomes smooth. Dimples also act as fins, reducing the upper surface temperature to lower than the lower surface, which in turn increases the lift particularly in low-speed and micro-scale airfoils [Kim, Jongmin, Zvi Rusak, and Nikhil Koratkar. 2003. ‘Small-Scale Airfoil Aerodynamic Efficiency Improvement by Surface Temperature and Heat Transfer.’ AIAA Journal 41 (11): 2105–2113].