基于微结构疏水界面减阻调控的微尺度动力学特性及沟槽仿生设计研究

The microstructural hydrophobic surface has excellent drag reduction effect, which makes it have a very wide range of applications and values in many aspects such as drag reduction and noise reduction of marine crafts, low-resistance and frost-reducing of aerospace, pipeline non-destructive transportation and other applications. In particular, the "shark skin effect" groove model for drag reduction provides the research enlightenment for the interface contact and adhesion mechanism. The interaction between the placoid microstructure and the counter-rotating vortex effectively could weaken the ability of buildup and uplift low-speed fluid, in further reducing the turbulent burst strength as well as the stability of the boundary layer flow. While it correspondingly weakens the development and exchange of momentum within the boundary layer, so as to achieve the purpose of regulating the hydrophobic drag reduction of the microstructure. The research intends to study the drag reduction mechanism of the microstructure hydrophobic surface with wetting behavior and the theoretical analysis of the micro-scale dynamics characteristics containing resistance and near-wall flow field and sliding interface of the hydrophobic model in different flows. A drag reduction model of micro-grooves that can consider slip boundary and thinning effect is established. Lattice Boltzmann equation of motion for the micro-scale flow on the hydrophobic surface is solved. And also the effect of the microstructure of the groove on the drag reduction can be summarized. The design method of the optimal shape and size of the groove microstructure based on the flow characteristics is presented. The study could propose new design thinking and significant reference for the drag-reduction behavior regulation of the moving body and the media interface.

微结构疏水表面优异的减阻效果使其在海洋航行器减阻降噪、航空航天低阻消霜、管道无损运输等方面有着十分广泛的应用前景与价值。尤以“鲨鱼皮效应”减阻沟槽模型为界面接触与粘着机理提供了研究启示，该鳞盾微结构与顺流向的反向旋转涡对相互作用，有效削弱集结及向上抬升低速流体的能力，降低湍流猝发强度，提高边界层流动稳定性。同时相应减弱发展和边界层内动量的交换，从而达到微结构疏水减阻调控的目的。本课题拟对微结构疏水表面润湿行为的减阻机理进行深入研究，理论分析疏水模型在不同流态下的阻力、近壁面流场、气液界面滑移等微尺度动力学特性，建立能够考虑滑移边界和稀薄效应的微沟槽疏水减阻模型，离散求解表界面微尺度流场的格子 Boltzmann 运动方程，总结沟槽微结构形式对流动减阻规律的影响，给出基于流动特性的最优沟槽微结构形状及其尺寸的设计方法。本课题研究为运动体与介质界面减阻行为调控提出了一种新的设计思路及重要参考。

微结构疏水表面优异的减阻效果使其在海洋航行器减阻降噪、航空航天低阻消霜、管道无损运输等方面有着十分广泛的应用前景与价值。尤以“鲨鱼皮效应”减阻沟槽模型为界面接触与粘着机理提供了研究启示，该鳞盾微结构与顺流向的反向旋转涡对相互作用，有效削弱集结及向上抬升低速流体的能力，降低湍流猝发强度，提高边界层流动稳定性。同时相应减弱发展和边界层内动量的交换，从而达到微结构疏水减阻调控的目的。本研究对微结构疏水表面润湿行为的减阻机理进行深入研究，采用流体动力学求解技术，确定合适的SST k-ω湍流模型，数值仿真不同的仿鲨鱼皮微结构模型的表面流动，计算表明雷诺数为4×10^4时，多行仿生鲨鱼皮微结构的减阻率最佳，减阻效果达到20.15%，其他构型的仿生结构也具有一定的减阻效果。经过研究分析，仿生微结构的减阻机理主要为：微结构之间存在沟槽，底部的流体流速较为平缓，所受的剪切应力较小，且该微结构能缓冲横向的流体脉动，并在附近产生了细小的漩涡，与主向流体产生对冲，避免了高速流体对避免的直接冲击，保持了层流边界层结构，减少了避免与流体之间的摩擦阻力，起到了减阻的作用。本研究完成了仿生微结构形式对流动减阻规律的影响分析，建立了基于流动特性的最优微结构形状的设计方法。该课题研究为运动体与介质界面减阻行为调控提出了一种新的设计思路及重要参考。