前缘点曲率可控的曲率连续前缘几何设计

Geometric Design of Leading Edge with Specified Curvature at Leading Edge Point

传统的圆形和椭圆形前缘通常在前缘与叶型拼接处仅能达到1阶连续,曲率不连续对压气机叶型的损失有较大影响.为解决此问题,提出了一种可指定前缘点曲率的曲率连续前缘设计方法.首先从几何插值的角度对前缘设计进行分析;然后根据叶盆、叶背曲线的定义方式获得构造前缘的端点插值条件;再指定前缘点的位置、切矢和曲率;最后利用经典的2阶几何插值算法分2段构造前缘,将叶背曲线起始点到前缘点作为1段,叶盆曲线起始点到前缘点作为1段.文中方法不仅保证前缘与叶盆、叶背曲线的曲率连续拼接,而且可指定前缘点曲率.设计实例和分析结果表明,该方法能够改善压气机叶型的气动性能.

Traditional leading edge generating method using circular and elliptical arc, only can achieve 1G continuity at the junction points between leading edge and suction or pressure curves. The discontinuous curvature around the leading edge has an important influence on the profile loss of compressor. A design method for continuous curvature leading edge with specifiable curvature at leading edge point was presented. Firstly the design of leading edge is analyzed from the view of geometric interpolation; secondly the endpoint interpolating conditions are obtained from the definitions of pressure curve and suction curve, and then the position, tangent vector and curvature at the leading edge point are specified; finally the leading edge is constructed as two parts by traditional geometric Hermite interpolation, with one from start point of pressure curve to leading edge, and the other from start point of suction curve to leading edge point. The leading edge generated using this method not only can guarantee curvature continuity between leading edge and suction/pressure curves, but also can specify the curvature at leading edge point.