基于NURBS曲线的任意圆心角度叶型前尾缘构造

Parametric construction of blade leading and trailing edges with arbitrary central angles using NURBS curves

  • 摘要: 具有良好灵活性的叶型前尾缘构造方法对于叶轮机械的叶型设计和优化至关重要。本文研究了一种在经典 NURBS 表示框架下,结合圆锥截线和圆弧几何特性,实现叶片前缘与尾缘的多自由度构造方法。该方法在叶栅气动弦长基本不变、保证补圆曲线与叶盆、叶背曲线在连接处的 G1 连续性的前提下,通过少量参数灵活调节圆锥截线的斜度、锥度和尺寸,实现对前缘和尾缘形状的有效控制。基于补圆类型及圆心角信息,求解控制点和权因子,精确构造任意圆心角度满足凸包性要求的圆锥截线。此外,将补圆参数与展向叶型截面数相关联,实现补圆几何随展向的动态变化,完成三维叶片复杂前尾缘的高效参数化建模。数值模拟表明,与原始叶型相比,采用本文方法构造前尾缘的跨声速叶片具有更高的等熵压缩效率,且前缘区域的激波强度明显减弱。

     

    Abstract: A highly flexible method for constructing the leading and trailing edges of airfoils plays a significant role in the design and optimization of turbomachinery blade profiles. This paper investigates a multi-degree-of-freedom approach for shaping the leading and trailing edges based on the classical NURBS representation framework, incorporating the geometric characteristics of conic sections and circular arcs. The proposed method enables effective control over the leading and trailing edge profiles by flexibly adjusting the slope, taper, and size of the conic section using only a few parameters, while maintaining the aerodynamic chord length of the blade row and ensuring G1 continuity at the junctions between the fillet curves and the suction/pressure side curves. Control points and weights are computed based on the specified fillet type and central angle to precisely construct conic sections satisfying convex hull requirements. Furthermore, the fillet parameters are linked to the number of blade sections along the spanwise direction, allowing for dynamic variation of the fillet geometry and enabling efficient parametric modeling of complex 3D blade leading and trailing edges. Numerical simulations demonstrate that, compared with the original airfoil, transonic blades incorporating the proposed edge construction method exhibit significantly improved isentropic compression efficiency and a noticeable weakening of shock waves in the leading-edge region.

     

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