Low Reynolds Number Laminar Separation Bubble Control Using a Backward Facing Step

A backward facing step is used to increase the lift to drag ratio of an airfoil with a separation bubble. Three airfoils are tested leading to the conclusion that the step works better for airfoils that have large separation bubbles near the mid-chord. It does not work well for separation bubbles near the leading edge, but has a positive effect for a separation bubble closerto the trailing edge. Results are preliminary and indicate that research is needed to characterize the size and location of the step, as well as the effect of freestream turbulence and Reynolds number.