摘要
Biomimetics has an immense potential to drive the next generation of technologies forward by propounding competent solutions from nature.For decades,the nonsmooth topography of most living creatures has been critical to their existence and survival.Contrary to human-made smooth surfaces,when adapted for fluid flow applications,nonsmooth surfaces can enhance the overall aerodynamic performance by reducing the drag force.Recently,the bioinspired scale structure of fish has been identified as a key biomimetic derivative for improving the aerodynamic efficiency in various cross-domain applications.This study investigates the aerodynamics of a fish scale array(FSA)NACA 0021 model at a specific Reynolds number(Re)of approximately 2.46×105 that is meant for laminar flow conditions using Computational Fluid Dynamics(CFD)tools and a subsonic wind tunnel facility.A 3D printed biomimetic FSA film is developed and affixed on the NACA 0021 wing profile for the experimental investigation,followed by flow visualization through the smoke tunnel facility.As proved qualitatively under specific aerodynamic conditions,the creation of velocity streaks has a major role in the drag reduction process.To obtain a clear perspective of flow across the overlapping fish scale structures,the results are focused on the central and overlapping regions of the FSA structure.The experiment has proved the existence of a combined formation of low and high velocity streaks in central and overlapping regions.The FSA 0021 model showed a maximum drag reduction of 9.57%,which was attributed to the streak formation phenomenon observed in the overlapping FSA configuration.
