融合微吹气的各向同性渗透材料对平板湍流边界层结构的影响研究

Study on the effect of isotropic permeable materials fused with microblowing on the turbulent boundary layer structure of a flat plate

  • 摘要: 黏性阻力是民用飞机所受阻力的主要来源之一,而湍流阻力在黏性阻力中占主导地位,因此开展湍流的减阻控制具有极其重要的工程和科学意义。本文在零压力梯度实验条件下,开展了融合微吹气的各向同性渗透材料对平板边界层的减阻控制研究。研究结果表明融合微吹气的各向同性渗透材料可以显著降低平板表面摩擦阻力,在本文中局部最大减阻率可达55.4%。此外,相比于单一的各向同性渗透材料控制,融合微吹气的各向同性渗透材料不仅提高了局部区域的减阻率,并且由于微吹气对湍流结构影响的“记忆性”,使得下游减阻区域的流向面积增加,提高了减阻的效率。由热线测速结果显示,融合微吹气的各向同性渗透材料可以降低边界层黏性底层的速度梯度,减少内外层之间的动量交换。通过PIV(Particle Image Velocimetry)流动可视技术表明,融合微吹气的各向同性渗透材料可以增加湍流边界层厚度和流向的脉动强度,同时还使得流展向的大尺度高速条带结构分解为小尺度结构,抑制了靠近壁面的自持过程和扫掠过程,从而实现减阻。

     

    Abstract: Viscous drag is one of the main sources of civil aircraft drag, and turbulence drag plays a dominant role in viscous drag, so it is of great engineering and scientific significance to carry out turbulence drag reduction control. In this paper, under the condition of a zero pressure gradient experiment, the drag reduction control of the plate boundary layer with isotropic permeating materials fused with micro-blowing is studied. The results show that the isotropic permeable material can significantly reduce the friction drag of the plate surface, and the maximum local drag reduction rate in this paper can reach 55.4%. In addition, compared with the control of a single isotropic permeating material, the isotropic permeating material integrated with micro-blowing not only improves the drag reduction rate in the local region but also increases the flow area of the downstream drag reduction region due to the "memory" of the influence of micro-blowing on the turbulent structure, improving the efficiency of drag reduction. Hot-wire velocity measurement results show that the isotropic permeable material with microblowing can reduce the velocity gradient of the viscous bottom layer of the boundary layer and reduce the momentum exchange between the inner and outer layers. The flow visualization technology of Particle Image Velocimetry (PIV) showed that the isotropic permeable material integrated with micro-blowing could increase the thickness of the turbulent boundary layer and the pulsation intensity of the flow direction. At the same time, the large-scale high-speed strip structure of the flow direction was decomposed into the small-scale structure. The self-holding process and sweeping process near the wall are suppressed, thus achieving drag reduction.

     

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