叶片前缘对吸力面边界层3维流动影响分析

Impact Analysis of Leading Edges on Blade Suction Surface Boundary Layer Three-dimensional Flow

为了分析叶片前缘形状对吸力面边界层3维流动过程的影响,对1组具有不同前缘形状的叶栅进行试验与数值模拟。以2维结论为基础,利用数值计算建立了前缘对吸力面边界层的2维影响与3维影响之间的联系。结果表明:对于1个竖直叶栅,端壁附近的展向截面吸力面边界层早期的发展过程主要保持2维特性,且这一特性能对边界层的3维流动产生直接影响。展向截面边界层形状因子与边界层展向流动趋势直接相关,在分离泡区域内,形状因子较大,使得边界层展向流动的趋势急剧增加,低能流体沿展向大幅发展。通过试验考察不同前缘叶型的竖直叶栅出口总压损失和出口气流角的展向分布发现,在2维计算中优秀的前缘造型或特定的前缘形状均能改善吸力面边界层的3维流动,有效减小整体的总压损失。

In order to study the influence of blade leading edge shape on three-dimensional flow process of suction surface boundary layer,a group of cascades with different leading edge shapes were studied experimentally and numerically. Based on the two-dimensional conclusions,the relationship between the two-dimensional and three-dimensional effects of the leading edge on the suction surface boundary layer was established by numerical calculation. The results showed that for a vertical cascade,the early development process of the endwall boundary layer along the spanwise section surface mainly maintains the two-dimensional characteristics,and these characteristics have a direct impact on the three-dimensional flow of the boundary layer. The spanwise section boundary layer shape factor is directly related to the spanwise flow trend of the boundary layer. In the separation bubble region,the shape factor is large,which makes the spanwise flow trend of the boundary layer increase sharply,and the low-energy fluid will develop significantly along the spanwise direction. Finally,the spanwise distribution of outlet total pressure loss and outlet flow angle of vertical cascades with different leading edge were investigated experimentally. It was found that excellent leading edge shape or specific leading edge shape in two-dimensional calculation can improve the three-dimensional flow of suction surface boundary layer and effectively suppress the overall total pressure loss.