叶片表面粗糙度对前弯压气机叶片流动特性影响的试验研究

Experimental Investigation of Surface Roughness on Flow Around Forward-Skewed Compressor Blade

关键词:  压气机  前弯叶型  表面粗糙度  雷诺数  攻角  喷砂

Key words:  Compressor  Forward-skewed blade  Surface roughness  Reynolds number  Angle of attack  Sand blasting

摘要:

为了探究叶片表面粗糙度对叶型性能的影响规律，对压气机前弯叶片进行了变雷诺数多攻角工况的叶栅试验。不同粗糙度（Ra=3.0,6.2,12.3）叶片是在轮廓度有所保证的前提下，通过线切割机械加工、喷砂工艺改变表面粗糙度的方式获得。试验结果表明，粗糙度升高确实会诱发层流提前转捩，引起吸力面层流分离泡消失，除此之外，在低雷诺数（Re=9×10⁵）下,Ra=3.0与Ra=6.2下叶片表面马赫数分布基本一致，到Ra=12.3时才会较明显表现出叶片吸力面峰值马赫数降低的现象。随着雷诺数升高，叶片表面马赫数分布随粗糙度变化的差异性逐渐显现，但当处于堵塞负攻角i=-6.4°下，粗糙度Ra≥6.2后，叶片性能却维持稳定。另外，粗糙度的增加会降低压力面的粘性损失，升高吸力面的粘性损失及尾迹掺混损失，因此随粗糙度升高，低雷诺数（Re=9×10⁵）下总压损失随粗糙度升高呈先增后降的趋势。在高雷诺数（Re≥1.08×10⁶），i=2.6°~-2.4°下粗糙度升高会导致损失升高，甚至发生严重的湍流边界层分离。与此同时，发现被研究叶型吸力面前缘（20%弦长前）马赫数分布对粗糙度并不敏感，不会因粗糙度的不同而发生变化。

Abstract:

In order to study the impact of the surface roughness on the blade performance, the experiment on forward-skewed compressor blade was carried out with different Reynold numbers and angles of attack. The different surface roughness blades （Ra=3.0,6.2,12.3） resulted from wire-electrode cutting and sand blasting,while the blade geometry was guaranteed. The results showed that the laminar separation bubble is removed due to the transition of laminar flow in advance by increasing surface roughness. For low Reynolds number（Re=9×10⁵）, the surface Mach number distribution of Ra=3.0,6.2 are similar while the peak of isentropic Mach number distribution at the suction side decreases at Ra=12.3,and the difference becomes larger because of increasing surface roughness as the Reynolds number increases, but the overall performance keeps stable at occlusion attack angle i=-6.4° with Ra≥6.2. On the other hand, the viscosity loss on pressure side would decrease with the increasing surface roughness, which is opposite on the suction side and wake mixing loss. For low Reynolds number (Re=9×10⁵), the overall total pressure loss first ascends and then descends with the adding of the surface roughness, and for high Reynolds number (Re≥1.08×10⁶), i=2.6°~-2.4°,the total pressure loss ascends all the time, even inducing serious turbulent boundary layer separation. Furthermore, the Mach number distribution of the leading edge(before 20% chord length) on the suction side would not change with the adding of the roughness.