不同导叶预旋角下离心压缩机径向间隙区雷诺应力的测量

Measurements for Reynolds Stresses under Different Inlet Prewhirl in Centrifugal Compressor

使用X热膜技术,研究了离心压缩机设计流量下3个不同进口导叶预旋角对径向间隙区雷诺应力的影响.结果表明:进口导叶为-20°时,径向间隙区的湍流强度和雷诺应力最大,0°预旋角其次,20°预旋角最小;湍动能大的区域,相应的雷诺剪应力也较大.在3个预旋角下,10%和50%叶高处的时间平均径向雷诺应力均明显大于切向雷诺应力,显示出明显的流动各向异性,叶轮出口处的时间平均径向雷诺应力为切向雷诺应力的1.5倍以上,但在扩压器进口处减少到1.25倍左右;90%叶高处的时间平均径向雷诺应力和切向雷诺应力值相差不到10%,流动更接近各向同性.0°预旋角下流动的各向异性最强.研究显示,需要更好的湍流模型来预测流动中复杂的混合过程.

The effects of inlet guide vanes （IGV） prewhirl angles on Reynolds stresses in radial gap between impeller and vane diffuser in a centrifugal compressor are experimentally investigated under design condition by X-type hot-film anemometry. The results show that the levels of the turbulence intensity and the Reynolds stresses in the radial gap get the highest under -20°of prewhirl angle, while they are moderate at 0°and the lowest at 20°of prewhirl angles. High levels of Reynolds shear stresses look to be related with high levels of turbulence kinetic energy, or vice versa. In the lengths of 10% and 50% spanwise, at three prewhirl angles, the time-average Reynolds stresses in the radial direction are obviously larger than that in the tangential direction to indicate the significant anisotropy of turbulence. At the impeller outlet the time-average Reynolds stresses in the radial direction are above 1.5 times larger than those in the tangential direction, and this ratio decreases to 1.25 at the diffuser inlet. However, in the length of 90% spanwise, the turbulence is close to isotropy since the difference of the Reynolds stresses in two directions is less than 10%. The degree of turbulence anisotropy at 0°of prewhirl angle is higher than those under other two prewhirl angles.