鲨鱼皮盾鳞结构减阻性能数值模拟

Numerical simulation on drag reduction performance of shark skin with denticle structures

海洋中快速游动的鲨鱼因其皮肤表面具有减少摩擦阻力的肋条状盾鳞结构,从而受到研究学者的广泛关注。为了指导减阻表面的设计与制造,选用数值模拟的方法对鲨鱼皮盾鳞结构的减阻机理进行了研究。通过扫描电子显微镜(scanning electron microscope,SEM)观察,获取鲨鱼盾鳞的微观结构,构建出简化的几何模型单元,并设计了不同分布规则和排布的单元阵列,形成了大面积非光滑仿生结构表面。利用Fluent软件对建立的计算域模型进行流体动力学仿真,同时与传统的矩形沟槽非光滑表面进行比较。数值模拟结果表明:仿生非光滑表面均减少了摩擦阻力,并且相较于矩形沟槽非光滑表面,简化盾鳞结构表面的减阻率明显增加;当入口速度为5 m/s时,对齐排布的简化盾鳞结构表面的减阻率可达到17.86%。最后,从壁面附近区域的流体流速和湍流动能2个方面对非光滑表面的减阻机理进行了分析。研究结果可望对设计和制备具有减阻功能的海洋装备仿生表面起到指导作用。

Owing to micro denticle structures, sharks are regarded as one kind of fastest swimmers in the ocean, the efficiency on drag control has aroused a huge attention from researchers. In order to guide the design and manufacture of drag reduction surface, the drag reduction mechanism of denticle scale structure was studied by numerical simulation method. Using scanning electron microscope(SEM), the micro morphologies of shark skin were observed. The observed denticles were simplified and a geometric model cell was constructed. Constructed arrays with different distribution and arrangement were designed to introduce a large-area non-smooth bionic surface. The fluid dynamics simulation was performed on the established computational domain model using Fluent. Traditional rectangular groove non-smooth surface was set as the control. Numerical simulation results show that the bionic non-smooth surface reduces the frictional drag. Compared with the rectangular grooves non-smooth surface, the reduction rate of drag for the simplified bionic surface is significantly increased. Under the inlet velocity of 5 m/s, the reduction rate of the aligned shield scale surface is observed as much as 17.86%. Finally, the drag reduction mechanism of non-smooth surface was revealed by fluid flow velocity and turbulent flow energy in the vicinity of the wall. The research results are expected to play a guiding role in the design and preparation of the bionic surface of marine equipment with drag reduction function.