Design And Manufacture Of Bionic Non-smooth Drag Reduction Surfaceand The Study Of Drag Reduction Technology

In recent years, with the increasing demand for energy and the requirements forenvironmental protection, how to find a both efficient and environmentally friendlymethodthat can realize drag reductionhave become hot issues for scholars from variouscountries. The non-smooth drag reduction technology based on bionics principle wasstudied, the non-smooth surface structure of organisms were abstractedasdimpleconcave, and the configuration of dimple concave was based on the phylloxy theory,thephyllotactic pattern dimple concave surface non-smooth surface used in field of air dragreduction was presented. Therefore, the following tasks were carried out:The growth characteristics of the plant tissue were analyzedand the phyllotaxygrowth curve was obtained, then applied the principle of least to fit the generatrix of therevolution body and the phyllotaxy growth curve and obtained the parameters that affectthe phyllotactic pattern, combined with practical engineering,the phyllotactic patterndimple concave surface was designed.The drag reduction effect of phyllotactic dimple concave surface of differentlocation on the revolution body was studied by the way of numerical simulation withAnsys Fluent, simulation results showed that the phyllotactic dimple concave arrangedon the rearward can achieve better total drag reduction effect; secondly, the dragreduction effect of dimple concave surface with parallel pattern, staggered pattern andphyllotactic pattern were comparedunder the same simulation conditions, simulationresults indicated that the phyllotcatic pattern dimple concave surface can achieve betterdrag reduction effect than the other two pattern surface; thirdly, the influence of the sizeof the dimple concave on the drag reduction was also studied, the range of dimpleconcave size that can reduce drag reduction was obtained; finally,using analysis ofrange, the factors that affect the drag of revolution bodywere analyzed and the optimalcombination andlevels were obtained, with the optimized parametersof the surface configuration on rearward of the revolution body, the total drag can bereduced by3.81%.By analyzing the influence on flow characteristics with near-wall region ofphyllotactic dimple concave surface on revolution body, it can be found that phyllotacticdimple concave decreased the wall shear stress of certain areas by reducing the velocitygradient of near-wall region, due to the rotating airflow formed inside dimple concave,the form of friction between the gas and the wall of revolution has been changed,it canbe found that if the same area were configured the same amount of dimple concave withdifferent pattern, the phyllotactic dimple concave surface have more dimple concave actas “ball bearing”, both in terms of reducing the friction and pressure drag thephyllotactic pattern dimple surface can have better results thanthe parallel pattern andstaggered pattern.