穿孔壁面通道流动阻力特性研究

THE FLOW RESISTANCE CHARACTERISTICS OF PERFORATED LINER DUCTS

  • 摘要: 利用计算流体力学方法对穿孔壁面通道内部流动进行了数值模拟,分析了其流动沿程摩擦阻力特性。计算中,假设流体不通过小孔进出穿孔壁面背后的吸声材料。经实验对比,采用Realizable k--" 湍流模型结合增强型壁面函数,可获得比较理想的计算结果,数值模拟与实验测量的压损值相对偏差在10% 以内。对于穿孔壁面通道流动阻力计算,提出了等效粗糙度概念,结合达西公式、克罗布鲁克公式计算获得了等效粗糙度数值。研究了穿孔板小孔孔径、穿孔率对等效粗糙度的影响,发现等效粗糙度与孔径成二次方关系、与穿孔率成线性关系。

     

    Abstract: In this paper, the inner flow of perforated liner ducts is studied numerically by the computational fluid dynamics method. The fractional resistance characteristics of the ducts are analyzed. In the simulation,it is assumed that the air flow will not go into or out of the sound absorbing material through the pinholes. It is found that the combination of the realizable k--" model with an enhanced wall function can be used for the simulation of this kind of duct flows, and the pressure drop deviation between the numerical simulation and the experimental measurement is less than 10%. In the flow resistance calculation for perforated liner ducts in the engineering design, the concept of equivalent roughness is proposed, which can be calculated by the Colebrook equation and the Darcy--Weisbach Formula based on the pressure drop data obtained by numerical simulations.The in fluence of the size of the pinholes and the perforation rate of the perforated plates on the equivalent roughness is examined. It is found that the equivalent roughness is proportional to the square of the perforation rate, and is linear to the size of the pinholes.

     

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