围绕旋翼飞行器的三维结构化运动嵌套网格生成方法

Generation Method for Three-Dimensional Structured Moving-Embedded Grid Around Rotorcraft

考虑到旋翼飞行器的旋翼各种运动和机身复杂外形特点,建立了一种鲁棒性高的三维结构化嵌套网格生成方法。采用三维Poisson方程对初始网格进行迭代,获得了高质量的旋翼桨叶三维结构化网格。以此方法为基础,以复杂外形几何体表面网格为初始网格,建立了一种抛物型法向外推方法。推进过程中,使用经抛物化处理的新Poisson方程进行光顺迭代,源项由Hilgenstock法确定,有效克服了椭圆型方程生成网格时边界点较难调整的困难。通过网格最小正交度的检测,表明了该抛物型方法的先进性。进一步将高效的挖洞法("Top map"法)和贡献单元搜寻法("Inverse map"法)引入上述三维结构化网格生成中,建立了围绕旋翼飞行器的运动嵌套网格生成方法,采用RANS方程分别对Caradonna-Tung旋翼和V-22倾转旋翼机流场进行计算流体力学(Computational fluid dynamics,CFD)计算,表明该网格生成方法能够满足CFD计算的需求。

Considering the characteristics of several kinds of rotor movements and complicated fuselage geometry shape of rotorcraft, a robust generation method for 3-D structured embedded grid is estab- lished. 3-D preliminary grids are generated by using the Poisson equations for iterations, then 3-D struc- tured grid around the rotor blade with high quality is acquired. Based on this method, a parabolic marc- hing method along the normal direction is established, which uses surface grid around complicated ge- ometry shape as its preliminary grid. In the marching process, new Poisson equations modified by para- bolic means, which source terms are determined by the Hilgenstock way, are used for smoothing itera- tions, and the difficulties of adjusting points on boundaries by using elliptic grid generation method are overcome effectively. The advantages of the parabolic method is proved by using examination of mini- mum orthogonality of grid. The efficient way of hole cutting （＂Top map＂） and donor cells searching （＂Inverse map＂） are introduced further to 3-D structured grid generation above, and the method for gen- erating moving-embedded grid around rotorcraft is established. It is demonstrated by conducting compu- tational fluid dynamics （CFD） calculations on the flowfields of Caradonna-Tung rotor and V-22 tilt-rotor aircraft respectively using the RANS equations that the grid generation method could meet the demands of CFD calculations.