包含多孔材料插件的突扩通道湍流计算

Calculation of Turbulent Flow in a Suddenly Expanded Pipe With Porous Insert

多孔材料插件常用于管道整流或消声.本文以二维和三维的突扩通道流动为研究对象,数值计算多孔材料插件的位置、厚度和渗透率对流动的影响。结果表明,多孔插件厚度的增加或渗透率的降低都将增大通道内的压力损失,而插件的位置对压力损失的影响则较小.通道内的涡强和速度脉动随着插件位置的后移及渗透率的增大而减小。对于包含单频谐波的非定常来流,经过多孔插件后的压力信号、轴向速度脉动、湍动能及湍动能耗散率等参数的波动幅值均降低,但相位不发生变化。

Porous inserts are widely used for straightening and silencing the flows in pipes. In this paper, turbulent flows in two-dimensional and three-dimensional suddenly expanded channels are calculated. The influences of three parameters of the porous inserts, i.e., the thickness, the permeability and the location, on the flow fields are studied numerically. The results show that the pressure loss in the channels increases when the porous insert is either enlarged in thickness or decreased in permeability, while the location of the porous insert has less effects on the pressure loss. With the increase of either the permeability or the distance of porous insert from the expansion, the strength of vortices and velocity fluctuations decrease. For the unsteady inflow which contains a harmonic wave, all the fluctuation amplitudes of pressure signal, axial velocity, turbulent kinetic energy and the dissipation rate of turbulence are reduced when the fluid flows through the porous insert, but the phases of these waves are not changed.