运用动态嵌套网格技术和双时间推进算法，对微型共轴式双旋翼的非定常粘性绕流进行数值模拟和研究.针对上、下两层旋翼间距离较小和流动粘性影响较大的特点，在动态嵌套网格技术的基础上引入滑移网格技术，保证了流动信息交换的准确性.首先，模拟低雷诺数下单旋翼的流动，结果与实验数据吻合较好，验证了算法的有效性；然后，利用该方法实现对微型共轴式双旋翼流场的数值模拟.结果表明，微型共轴式双旋翼流场中，桨尖涡起主要作用，其以螺旋方式向下运动，同时与周期性运动的旋翼相互作用，使得作用在旋翼上的总体拉力呈现出周期性的变化规律.

Unsteady viscous flows of a microcoaxial rotor are simulated and studied using moving overlapped grids and the dualtime stepping method. We discuss the small space between the up- and down-rotor and large flow viscosity, and introduce a sliding mesh based on moving overlapped grids, which ensure accurate exchange of flow information. Micro-single rotor flows with a low Reynolds number are calculated. The results are consistent with experimental results, showing effectiveness of the algorithm. Microcoaxial rotor flows are then simulated with this method. The results indicate that the blade tip vortex, which moves down in a spiral way, plays a leading role in microcoaxial rotor flows. It makes the total thrust of the rotor periodic due to its interaction with the rotary rotor.