基于非结构嵌套网格的旋翼前飞流场计算

Improving Numerical Simulation of Rotor Forward Flight Flow Field with Unstructured Dynamic Overset Grids

发展了一种基于线性弹簧理论的非结构动态嵌套网格方法,通过求解非定常Eu ler方程模拟了旋翼的前飞流场。根据距离参数快速生成便于计算的两个重叠网格子域,利用运动区子域网格的转动来模拟旋翼的旋转运动,并对其运用线性弹簧动态网格技术来处理旋翼的挥舞和变距运动。发展了一种快速查找插值贡献单元的方法,无需建立Inverse网格,提高了计算效率和精度。使用高效双时间方法分区求解非定常Eu ler方程,两个子域的流场参数在重叠区进行耦合。计算了旋翼的两种前飞状态,所得结果与实验和文献结果都很吻合。

Aim. Existing methods for the numerical simulation of rotor forward flight flow field, in our opinion, still suffer mainly from two shortcomings： （1）hole map must be repeatedly established for structured dynamic overset grids; （2）searching for donor elements with Inverse MapE43 is somewhat slow. By using unstructured dynamic overset grids, we can obviate these two shortcomings, thus improving the efficiency and precision of numerical simulation. In the full paper, we explain in detail how to improve such numerical simulation; in the abstract, we just add some pertinent remarks to listing the three topics of explanation： （1）the motion of blades; （2）unstructured dynamic overset grid system; （3）numerical simulation; the subtopics of topic 2 are the establishment of overset grids（subtopic 2. 1）, searching for donor elements（subtopic 2.2）, data transmission（subtopic 2. 3）, and linear spring analogy（subtopic 2.4）; under subtopic 2. 1, we explain the fast generation of two overlapping subdomains-rotational area and static area; under subtopics 2. 1 and 2. 2, we explain why we do not need to repeatedly establish hole map and why we can fast search for donor elements without generating an Inverse Map ; under subtopic 2.4, we describe the linear spring analogy for treating the flapping and pitching motions of the rotor; the subtopics of topic 3 are governing equations （subtopic 3. 1） and time matching（subtopic 3. 2）; under subtopic 3. 2, we explain solving unsteady Euler equations with an efficient physical time matching technique called dual time matching. Finally we give a numerical simulation example. The simulation results, given in Figs. 7and 8 in the full paper, show preliminarily that our calculated results are in fairly good agreement with the test data in the paper by Caradonna et al.