Effect of Airfoil Thickness, Camber and Reynolds Number on Plunging Airfoil Propulsion

Abstract

The flow over an airfoil undergoing pure plunging motion was simulated to study the effect of airfoil thickness, camber and Reynolds number on the thrust generation and propulsive efficiency. The plunging motion of the airfoil was implemented by the introduction of a source term in the Navier-Stokes equations. At a Reynolds number of 20,000, for symmetric airfoil shapes, it was found that increasing the thickness of the airfoil can benefit both thrust generation and propulsive efficiency. When the airfoil thickness was increased from 6% to 15%, the time-averaged thrust coefficient and propulsive efficiency were increased by almost 200%. For a cambered airfoil, around 6-10% loss in both thrust coefficient and propulsive efficiency was found compared to a symmetric airfoil. By varying Reynolds number from 20 to 200,000 for flow over a plunging NACA0015 airfoil, it has been found that both the thrust coefficient and propulsive efficiency increase with increasing Reynolds number.