基于结构化设计的多孔材料渗透率的实验研究

介于流体和固体之间的多孔材料，能够有效稳定壁面剪切层、抑制涡脱落以及调控尾迹流场，从而减小气动阻力与降低噪声，是一种独特潜力的钝体绕流被动控制方法。以往研究表明，决定流动与噪声控制效果的关键参数是渗透率而非孔隙率。传统多孔材料（例如金属泡沫、聚氨酯纤维等）通常具有随机的内部结构，难以精确调整孔隙率以及渗透率大小。利用3D打印技术，使得结构化多孔材料设计成为可能，方便精确控制模型的内部结构，进而实现高渗透率的多孔材料结构设计。本研究自主搭建多孔材料渗透率的实验测量平台，并设计多种结构化多孔材料的实验模型。通过实验测量获得结构化多孔材料的流阻和渗透率等参数，并对比相同孔隙率下的传统与结构化多孔材料的渗透能力区别。之后通过改变结构化多孔材料几何参数，进一步研究孔径大小（PPI）、面密度与孔形状对渗透能力的影响。其次，基于渗透率测试的结果，筛选优化的结构化多孔模型，指导结构化多孔层方柱的模型设计，以获得对流场与声场的有效控制进而实现减阻降噪的效果。下一步工作将在南方科技大学气动声学风洞中对结构化多孔层方柱的升阻力与远场噪声进行试验测试，以验证多孔材料渗透率对钝体减阻降噪性能的影响。

The porous material between fluid and solid can effectively stabilize the wall shear layer, restrain vortex shedding and control the wake flow field, so as to reduce aerodynamic drag and noise. It is a unique potential passive control method for flow around blunt bodies. Previous studies have shown that the key parameter determining the effect of flow and noise control is permeability rather than porosity. Traditional porous materials (such as metal foam, polyurethane fiber, etc.) usually have random internal structure, and it is difficult to precisely adjust porosity and permeability. It is possible to design structured porous materials using 3D printing technology. It is convenient to accurately control the internal structure of the model, and realize the structural design of porous materials with high permeability. In this study, we built the experimental platform for permeability measurement of porous materials, and designed the experimental models of various structured porous materials. The flow resistance and permeability of structured porous materials were obtained by experimental measurement, and the difference of permeability between traditional and structured porous materials with the same porosity was compared. After that, the effects of pore size (PPI), surface density and pore shape on permeability were further studied by changing the geometric parameters of structured porous materials. Secondly, based on the permeability test results, the optimized structured porous model is selected to guide the model design of the structured porous layer of rectangular cylinder, so as to achieve the effective control of the flow field and sound field, and achieve the effect of drag and noise reduction. In the next step, the lift drag and far-field noise of a rectangular cylinder with structured porous layer will be tested in the aeroacoustic wind tunnel of South University of science and technology to verify the influence of porous material permeability on drag and noise reduction performance of rectangular cylinder.