Determination of Optimum Mixing Parameter for Oil Flow Visualization

It has been very important to determine the flow pattern on the surface of any object. Many times, understanding the flow pattern on the surface of the body has been a priority. With flow visualization techniques, separation points, separation lines, streaklines, and surface shear stress patterns can be examined. A surface oil flow visualization study is carried out on NACA 0020 airfoil with a leading-edge tubercle at a Reynolds number of 200,000. The purpose of this study is to find the optimum oil mixture that gives the best results on the airfoil profile. Flow visualization experiments are conducted at 5°, 10°, 15°, and 20° angles of attack on the NACA 0020 airfoil model using five different oil mixtures. The tubercle leading-edge of the model has double amplitude (a1 = 0.05c, a2 = 0.0125c) and double wavelength (λ1 = 0.5c and λ2 = 0.125c). As a result, it is observed that there is no definite mixing ratio, and the oil mixture should change according to the flow parameters.