Study on the relationship between geometric features and aerodynamic performance of bionic wings

To reveal the relationship between the special structures of birds' wings and their aerodynamic performances and hence provide useful information and support based on bionics theory for the design and development of high efficiency and low noise bionic airfoils, four kinds of birds (red billed Leiothrix, black tailed Grosbeak, starling, pigeon) as research objects were scanned using 3D laser scanner to reconstruct bionic wing models. Three-dimensional bionic airfoils from various sections of the birds' wings were obtained. Numerical simulation was conducted to investigate the aerodynamic performances and corresponding noise characteristics of the bionic wings. Firstly, through comparing the aerodynamic performances of the wings at varied attach angles and different Reynolds numbers, it was found that the performance curves of the four bionic wings change consistently, and are influenced by the Reynolds number in the similar way. When Reynolds number increases beyond 100 000, the performances of the bionic wings show little difference with the change of Reynolds number. The starling bionic wing performs better but only suitable for the case where the attack angle has little change. By contrast, the wing of red billed Leiothrix performs worse while its performance is not dependent on the angle of attack. Besides, the wings of good-at-flying birds can be divided into two parts: the root part of the wing is overall bending with asymmetrical airfoil; the top part is generally straight with symmetrical airfoil. The noise characteristics in certain cases were revealed according to the results of noise simulation. Also, the wake and flying speed can influence the distribution of noise.