Study On Drag Reduction Performance Of Adaptive Bionic Non Smooth Structure

With the increasingly exhaustion of the non-renewable energy resource, the model of low carbon and sustainable development has become popular among human beings. In the sector of Large transport ships, plane and pipeline transportation, the surface viscous resistance a object facing in flowing field account for 70%in the total resistance. Large amount of energy are consumed to overcome the resistence in the surface. Therefore the study of resistance reducing technique has a profound significance.As an important branch of fluid resistence reduction technique, the resistence reduction technique of bionic grooved surface has made big headway over the past ten year and more. During the swimming process of a dolphin, it's skin can feel the change of the outer flowing area, then it will change it's shape in real time by the nervous system. With the acceleration of it's swimming speed, the dolphin's skin will change from smooth to nonsmooth certain geometrical shape, and change with the border of the skin-outer flowing area.This paper has taken the dolphin's skin as the biological prototype. Taking the feature of the structure of the dermal ridge as follows:having diverse angle to the flow direction to adapt the changing height. In order to explore the practical solution to keep better drag reduction performance in relatively extensive speed or flow area, we have done the two aspects works.At first, take the theoretical results of fair current groove drag reduction technology as the start point, and set the data to calculate the model to test the figure of the drag reduction effect of the groove surface in different angles and different speeds. The experiment result shows that when the angel with the water (flow) direction in the groove are 0°,30°,45°,60°, and 90°, the drag reduction performance of the groove is the worst when the angle is 45°. When the velocity of water flow is low, the fair current and the 30° groove have better drag reduction performance. When the velocity of water flow is high, the change span of the drag reduction performance of the crosswise flow and the 60° groove is smaller than the fair current groove.In addition, combining with the relative theoretical results of the current research of the adaptive drag reduction technology, an adaptive surface drag reduction scheme was designed, and the numerical test analysis of the drag reduction performance was made by combining the user-defined function programs provided by the software Fluent.The numerical results demonstrate that this method has a certain reference value for the study of flexible wall adaptive drag reduction technology.