微小型摆线桨气动特性数值研究

Numerical Study on the Aerodynamics of Micro/Small Cycloidal Propeller

对微小型摆线桨模型进行了理论分析，确定了一种常见的桨叶绕自身轴旋转运动的规律。由于摆线桨产生的气动力主要来自于桨叶自转带来的动态升力，通过NACA0012翼型低雷诺数动态失速过程的数值模拟和实验对比，验证了采用嵌套网格技术的非定常N-S方程数值解法的准确性。通过对摆线桨二维非定常流场的计算和分析，得到了在悬停和前飞状态下，摆线桨产生气动力的大小、方向以及气动效率与桨叶运动规律的关系。然后分析了不同数量桨叶之间的相互干扰，发现3-4片桨叶较为合适。最后对三维摆线桨流场进行了仿真模拟，发现在转速不变的情况下，随着前进比J的增加，摆线桨产生的矢量推力大小变化不大，但方向变化明显。

Based on the theoretical analysis of micro cycloidal propeller model, a common law of pitch motion around its own axis of the blade was determined. Since the motion of cycloidal propeller contained the dynamic stall process, by comparing numerical simulation results with experimental results of the dynamic stall process of NACA0012 airfoil at low Reynolds number, the accuracy of numerical solution of the unsteady N-S equation on overset grid was veriifed. By simulation and analysis of 2D unsteady lfow ifeld around the cycloidal propeller in hovering and forward lfight, the relationship of the generated aerodynamic force and power with the law of the motion of the blades were obtained. Then with the analysis of the mutual interference to aerodynamic force and power between the blades with different numbers, taking account of the aerodynamic efifciency, the number of the blades should be set as three or four more appropriately. Finally, by simulation of the 3D lfow ifeld of cycloidal propeller, it was found that at the constant speed, with the increase of forward ratioJ, the value of the vectored thrust produced by cycloidal propeller changes little, while the direction of the thrust vector changes rapidly.