Numerical Simulation Research On The Drag Reduction Of Body With Non-smooth Bionic Surface

Based on bionic methodologies, with abstraction and simplification, five non-smooth units used to process high-speed body, namely triangle groove, semi-cycle groove, rectangle groove, convex dome and spherical dimple are studied. Subsequently, the models of computational domains of 50 bionic non-smooth bodies in their entirety are built with SolidWorks and Gambit. Computational domains are meshed with structured grid and local grid refinement is used to improve the quality of grid. With Fluent software, the experiments are carried out to numerically simulate a three-dimensional flow field outside the body, and the findings of how 50 non-smooth bodies affect drag reduction in terms of shape, spacing and depth of non-smooth units are obtained.This paper gets the drag rate of the surface of some kinds of non-smooth rotating objects through numerical experiments. And this paper compares the drag rate of the non-smooth rotating objects with that of the smooth rotating objects. By calculate the 28 varied-parameter models with triangle groove, we get the scope of parameters of the optimize unit which has the effect of decreasing drag. According to the results, we determine the parameters of the other 4 kinds of units. And then, we find that the drag rate of the 5 types of units is to increase and then decrease. By the simulate calculation, we get the minimum value of the drag rate of this 5 types of units. The drag rate of triangle groove model can get its minimum value and the maximum drag reduction rate is 12.02% when the depth of groove H=0.6mm and spacing of groove S=1.6mm. When H=0.4mm and S=1.4mm, the drag rate of semi-circle groove model can get its minimum value and the maximum drag reduction rate is 13.11%. Similarly, when H=0.6mm and S=1.4mm, the drag rate of rectangle groove model also get its minimum value and the maximum drag reduction rate is 11.62%. However, with respect to the unit with convex dome and the unit with spherical dimple all get they best effect of drag reduction when H=2.0mm and S=0.8mm. The maximum drag reduction rate of them is respectively 13.85% and 14.58%.Finally, based on the comparison between simulated results of non-smooth unit and that of the smooth unit, it is found that the mechanism of non-smooth surface characteristic of drag reduction is to decrease sheer stress on unit's surface. In order to verify the simulated results, we built an experimental platform. We put the unit into a cup that is full of oil. According to the temperature of the surface of the cup, we can find indirectly the effect of drag reduction of the unit. The experiment has an obvious result, the drag reduction rate of triangle groove is 11.11%.