The effect of trip wire roughness on the performance of the Wortmann FX 63-137 airfoil at low Reynolds numbers

An experimental investigation was conducted on the performance and boundary layer characteristics of the Wortmann FX 63-137 airfoil with and without trip wire roughness. Data were obtained through use of a three-component strain gage force balance and static pressure measurement equipment at a test Reynolds number of Rc = 100,000. Emphasis was placed on determining the effect of trip wire placement and size on such performance parameters as (Cl/Cd)max and (Cl3/2/Cd)max. Prediction of transition location by the criterion due to Tani and Gibbings was found to have limited application. Most trip wire locations resulted in degraded performance, but for some locations, minimum drag was reduced, maximum lift to drag ratio increased, and hysteresis averted.