基于动态嵌套网格技术的微型共轴式双旋翼流场的数值模拟

Numerical Simulation of Flows over Micro-coaxial Rotor Based on Moving Overlapped Grids

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.