基于贝塞尔曲线的液力变矩器三维叶片造型方法

Three Dimensional Torque Converter Blade Modelling Based on Bezier Curves

为满足液力变矩器三维流动设计的需要,解决传统基于一维束流理论叶片造型方法精度差、适应性低的缺点,提出基于贝塞尔曲线及保形变换的三维叶片造型方法。叶片二维型线由骨线叠加厚度分布的形式构造,叶片骨线和厚度均由两段三次贝塞尔曲线构成。为实现直接通过关键几何参数进行叶片设计,建立叶片几何参数与贝塞尔曲线控制点之间的数学关系式。利用保形变换方法进行叶片二维型线与三维曲线间的无误差转换,将二维叶片型线投影到循环圆环面生成三维叶片曲线,然后再堆叠三维曲线以构造叶片实体。新型叶片造型方法能够实现二阶导数连续、曲率连续的叶片曲线设计,从而提高了叶片液力性能,同时改善了叶片造型精度及适应性。利用新型造型方法对原始液力变矩器叶片进行优化设计,结果表明,新方法优化后的叶片液力性能要明显优于初始叶片,验证了新方法的可行性。

Because of the lack of accuracy and flexibility, the traditional blade modelling method is not suitable for torque converter 3D flow design. The novel 3D blade modelling approach based on Bezier curves and conformal transformation is proposed to solve the problem. The 2D blade profile is constructed by adding a thickness distribution to the camber line, and both the camber line and thickness distribution composed of two cubic Bezier curves. The control points are derived from the main geometric control parameters, by which geometric blade design is achieved. The conformal transformation is carried out to transform between 2D blade profile and 3D blade curve, which improves the design accuracy. The 3D blade entity is constructed by stacking 3D curves. The second derivative and curvature of the blade curve generated by the novel method are continuous, thus the hydrodynamic performance is improved, and the novel blade design method improves the accuracy and flexibility. An optimum pump blade is generated based on the new method and then tested. The hydrodynamic performance of the optimized torque converter is improved and thus the novel Bezier blade modeling method is validated.