Research On Hydrodynamic Characteristics Of Bionic Concave-convex Structure Based On Different Materials

Cylinders and airfoils are very important infrastructures in the fields of shipping,aviation and architecture,and have a very wide range of engineering applications.Studying the hydrodynamic performance of cylinder and airfoil can provide a more direct reference for the optimal design of structure,which is also a hot research topic of domestic and foreign scholars.In animals and plants of nature,the Blossom of the Saguaro Cactus and humpback pectoral fin are flexible structures with bionic bumps,corresponding to the two basic structures of the cylinder and airfoil.In this paper,the principle of bionics and the application of flexible materials to the hydrodynamic direction were studied.The shape of Blossom of the Saguaro Cactus and humpback pectoral fin were used for reference.The effect of flexible material was also considered.The numerical simulation and experimental research have been carried out.It provides a new route for the research and design of the cylinder and airfoil in the field of engineering.Researchers at home and abroad had conducted some studies on rigid bionic bump structures and two-dimensional flexible structures.However,few studies had combined bionic bump patterns with flexible materials to systematically study them.In terms of bionic cylinder structure,this article was based on the morphological characteristics of the Blossom of the Saguaro Cactus,a three-dimensional model and its control domain of fluid and solid were established.The numerical simulation analysis of the flow around the rigid and flexible imitations of the Blossom of the Saguaro Cactus under different Reynolds numbers was carried out.The lift,drag and flow field characteristics were obtained.It was found that the turbulent vortex street was formed by the flow around the cylinder,which produced the vortex induced vibration and had the obvious three dimensional characteristics.And the shape of the irregular section and the flexible material had a certain influence on the flow around the cylinder in most of the working conditions.Aiming at the numerical calculation results of the imitations of the Blossom of the Saguaro Cactus,this paper adopts 3D printing method to make a model structure.The experimental study was carried out in the circulation water channel.The results showed that compared with the cylinder,the imitations of the Blossom of the Saguaro Cactus with irregular section generally had the effect of drag reduction and vibration reduction,while the effect of flexible material was general.In terms of bionic airfoil structure,the three-dimensional geometric model was designed by observing the contour of the pectoral fin of the humpback whale,and the relevant variables were set up.The lift,drag and flow field characteristics of the imitations of the fin of the humpback whale were obtained under different angles of attack.The results showed that the flexible material had significant influence on the fin studied in this paper.