基于NURBS曲线的离心透平叶型设计

Centrifugal Turbine Blade Design based on NURBS Curves

针对离心透平的环列叶栅叶型,采用四段三次NURBS曲线(非均匀有理B样条曲线),分别对前缘圆弧、尾缘圆弧、叶背、叶盆进行参数化表达,环列叶栅叶型的设计自由度为14个,可灵活进行局部调整。采用高精度流场模拟方法,基于优选法,获得气动性能较高的设计参数。结果表明上述方法简单易行,优选出的离心透平级设计工况及变工况气动性能都得到了显著提升,与已有文献相比,单排静叶总压损失系数降低18.85%,整级轮周效率提高4.08%,动叶叶片数也减少17个。

The purpose of this paper is to propose an innovative design method for the optimal shape of the annular cascade blades of a centrifugal turbine. Four cubic NURBS curves were used as parameterized expressions for the leading edge,trailing edge,suction surface and pressure surface of the blade. The design freedom degree of the centrifugal turbine blade was 14 but could be flexibly adjusted for the partial area of the blade. Based on the optimum seeking method,the favorable design parameters of the blade that can produce optimal aerodynamic performance were determined with the aid of high accuracy schemes in numerical simulations of turbine flow field. The results obtained in this work suggested that the design procedure proposed for the centrifugal turbine blade in this paper is relatively easy and convenient to be performed in practice. The aerodynamic performance of the centrifugal turbine stage with the optimized blades has been found to be significantly improved at both design and off-design conditions. Compared to the published results in available literature,the total pressure loss coefficient of a single-row of stator blades is reduced by 18. 85%,and the adiabatic efficiency of the turbine stage is increased by 4. 08%. Furthermore,the number of turbine rotor blades is reduced by 17.