Numerical Assessment of the Backward Facing Step for NACA 0015 Airfoil using Computational Fluid Dynamics

Abstract

The objective of this work was to investigate the lift and drag characteristics of a NACA 0015 airfoil with a backward facing step. For a free stream velocity of 30m/s, the point of separation was determined via CFD analysis for an increasing angle of attack. A backward facing step was then introduced just prior to the point of separation which extended till the trailing edge. Computational studies were conducted with the goal of enhancing the aerodynamic performance of the airfoil by inserting several backward facing steps of gradually increasing depth. The CFD analysis was conducted for 30 m/s wind speed, with steps placed just prior to the point of separation for 18° angle of attack. The results produced show that as much as a 26% reduction in drag is possible by introducing the step. But at the same time, about 12% reduction in the lift was also observed. A wind tunnel test on a NACA 0015 was also conducted to verify the results from CFD analysis. Predominantly the goal of this thesis was to numerically determine whether or not the aerodynamic performance of an airfoil can be enhanced by introducing a backward facing step on the upper surface of the airfoil.