粗糙度对压气机叶型性能影响的数值模拟方法研究

Investigation of the Numerical Method for the Influence of the Surface Roughness on the Performance of Compressor Blade Airfoils

表面粗糙度对压气机叶型性能有重要的影响,但如何利用数值模拟方法还原粗糙度对叶型性能的影响规律仍是当前需要解决的问题之一。本文通过精细地设置叶栅对比实验,单独改变叶中区域特定位置粗糙度大小,从而得到了粗糙度大小对叶型性能的影响规律。以此实验数据为依据,分别通过改变湍流模型、壁面第一层网格高度、进口湍流度、等效沙砾粗糙度等参数,利用CFX数值模拟软件对粗糙度大小对叶型性能的影响展开了数值研究。结果表明,当叶表较为粗糙时,叶表边界层的发展状态对叶型性能有较大影响,所以数值模拟时应启用转捩模型而非全湍流设置。壁面第一层网格的高度应参考计算所选取的粗糙度大小。此外,在数值模拟时进口湍流度的准确获取也很重要。

Surface roughness has an important effect on the performance of compressor blade airfoils,but it is still one of the unsolved problems that how to simulate this influence by using CFD methods.In this paper,a series of compressor cascade experiments were set elaborately,i.e.,the roughness of a specific position in the middle part of the blade was changed separately,so as to obtain the influence rule of the roughness on the performance of blade airfoils.Based on the experimental data,ANSYS CFX was used to simulate the influence of the surface roughness on the performance of compressor blade airfoils,and the effect of some numerical factors such as the turbulence model,the height of the first grid near the wall,and the inlet flow turbulence intensity on the numerical accuracy was investigated.The results showed that when the blade surface is rough,the evolution of the blade surface boundary layer and the height of the first grid near the wall have great influence on the performance of blade airfoils,so the transition model rather than full turbulence should be adopted when the turbulence model is used,and the height of the first grid near the wall should be selected according to the magnitude of the surface roughness.In addition,the inlet flow turbulence intensity has also great influence on the performance of blade airfoils,so it should be also considered carefully in the simulation.