Bezier函数型径向弯叶片对电站锅炉给水泵空化性能影响研究

Radial bending blade of Bezier function and the effect of cavitation performance on boiler pump

为满足1000MW超超临界电站锅炉给水泵大容量高参数的设计要求,通过CFD技术对锅炉给水泵叶轮的空化性能进行数值研究.提出一种基于Bezier函数思想的径向弯叶片几何参数设计方法,并引入正弯叶片和反弯叶片两种叶片径向弯曲结构.结果表明:直叶片必需空化余量为22.8m,与试验值的绝对误差仅为0.2m,预测结果具有一定的精度;反弯叶片必需空化余量为22.3m,空化性能最好;正弯叶片在叶片进口处压力面最先出现空泡,吸力面空化面积最大,而反弯叶片吸力面空化面积最小;3种径向弯叶片空化后在沿叶高中间流线相对位置0.2处叶片表面存在最大压差,可能导致叶片局部发生断裂.

To meet the demands of large capacity and high parameters on 1000 MW ultra-super- critical pressure boiler feed pump, the numerical simulation of cavitation performances of boiler feed pump blades were carried out through CFD applications. A new design method of geometric profile parameters based on Bezier function was proposed. Two types of radial bending blades were introduced, i.e. forward curved blade and reversed curved blade. Results indicate that the NPSH （net positive suction head） of straight blade is 22.8 m, and the absolute error is 0.2 m. Compared with straight blade and forward curved blade, reversed curved blade has the best cavi- tation performances, and the NPSH is 22.3 m. The vapor firstly generates at pressure surface of forward curved blade near the leading edge, and the cavitation region of suction surface is the largest, but the reversed curved blade is opposite. There is a maximum pressure drop on the middle streamline of blade at the relative position of 0.2, which could lead to local fracture.