THE LEADING-EDGE TUBERCLE MODIFICATIONS TO THE BIOMIMETIC WINGS

An experimental investigation was conducted to better understand the effects of the humpback whale flipper's tubercles on biomimetic models. Different configurations of tubercles were investigated for five biomimetic flipper models by performing force measurement experiments at Re = 5×104, 8×104, and 1.2×105 and surface oil flow visualization at Re = 1.2×105. The experiments were carried out with five different test models that are two baseline models, two simply designed tubercle models with uniform distribution, and a proposed tubercle model having a more realistic approach. The proposed model pattern was created by summing two wave functions. The results indicated that the models having leading-edge tubercles increased lift and stall angle and reduced drag than the baseline model. The C3 designed with a more realistic approach has the best performance within other tubercles and baseline models for all Reynolds numbers. It has been seen that the maximum improvement is achieved from the lift coefficient by approximately 18% with the C3 at Re = 5×104. According to flow visualization results, the LSB formed in the smooth baseline model was replaced by a CRVPs in the tubercle models. The improvement of the aerodynamic characteristics is due to the CRVPs formed by the interaction of the leading-edge tubercles with each other and wavelike trailing-edge flow separation pattern. One of the significant findings to emerge from this study is that more realistic approach has the potential to obtain better performance than model with uniform distribution of tubercles.