叶型几何变形对涡轮载荷分布的影响

Influence of a turbine airfoil's geometry deformation on loading distribution of a turbine

为了寻找将中部加载涡轮叶片改型为后加载涡轮叶片的设计规律,用三维流体软件NUMECA对某四级动力涡轮的第一静叶进行了后加载改型设计研究.通过调整Bezier曲线控制点改变叶型的中弧线和内背弧.数值模拟结果表明:保持叶型中弧线轴向长度不变而缩小中弧线的周向长度,同时通过增加叶型厚度来控制喉部面积,可以得到性能先进且保持与原始涡轮级动叶气动匹配的后加载静叶叶型.三维流场研究表明:后加载叶型改善了叶型损失,同时减小了二次流损失,改型的后加载静叶使得涡轮级效率提高了0.62%.

In order to find the design law that enables a mid-loaded turbine blade to be inserted into an aft-loaded turbine blade, the first stator of a four-stage power turbine was researched by the three-dimensional fluid dynamics software NUMECA. The camber curve and side curve of the blade were controlled by using a Bezier curve. Numerical simulation shows that when keeping the axial length invariant, narrowing the tangential length of the camber curve of the turbine and in the meantime increasing the thickness of the blades can control the throat area, and thereby obtain aft-loaded turbine cascades, which are advanced in performance and matching with the original ones. Study of three-dimensional flow fields shows that aft-loaded turbine cascades can reduce both profile loss and secondary flow loss. The new turbine cascades which are characterized by aft-loaded airfoil increase the turbine efficiency by 0.62%.