Multidisciplinary research method for designing and selection of bio-inspired profiles in the conceptual designing stage

A multidisciplinary research method was employed with the intention to create a series of bio-inspired flattened airfoils, observe their aerodynamic characteristics, and analyse their applicability to small devices or to designs of high-speed trains, within the shortest period in the conceptual stage. A research specimen of a kingfisher, selected for biomimicry, was examined with the following methods: visual inspection, analysis of photographs, manufacturing quality control measurement with a 3D laser scanner, and microscopy. A basic multi-arc-line profile, re-engineered from the overlapped specimen shape data and based on the observations, was used for designing a series of seven derived airfoils. The aerodynamic characteristics of the bio-inspired airfoils were obtained with the panel methods at low and moderate subsonic speeds, while the small transonic difference method was used in the high-subsonic speed range. Basic and ellipse-like airfoils produce higher total drag at low and moderate velocities and higher forebody drag in the high-subsonic range when compared to derived and parabola-like airfoils. The obtained critical Mach numbers are in the range from 0.76 to 0.78, where three bionic airfoils show values equal to or smaller than the values of ellipse- and parabola-like airfoils. The profile with the shortest bio-inspired relative chord has a higher critical Mach number value than the parabola-like profile. The sonic lines above these profiles appear at close positions. The applied set of examination methods of the bio-inspired design is not time consuming and produces sufficiently good results in the conceptual stage. Therefore, a further development of unique and adjusted numerical methods and codes at pre-computational fluid dynamics run is encouraged, together with shape parameterization.