基于高阶逆风通量差分裂格式的直升机旋翼前飞流场模拟  

Calculations for the flowfield of helicopter rotors in forward flight based on high-order upwind flux-difference splitting scheme

作　　者：招启军[1] 徐国华[1] 

机构地区：[1]南京航空航天大学直升机旋翼动力学国家级重点实验室,江苏南京210016

出　　处：《空气动力学学报》2005年第4期408-413,共6页Acta Aerodynamica Sinica

基　　金：全国优秀博士论文专项基金(200050)资助

摘　　要：描述了三维雷诺平均NS方程数值模拟前飞状态旋翼非定常流场的方法和模型。在该模型中,将三阶逆风格式(MUSCL)与通量差分裂方法相结合,无需添加人工粘性,因而可有效地减少Jameson二阶中心差分有限体积法导致的旋翼尾迹数值耗散。为充分考虑旋翼尾迹对流场的影响和计入桨叶的旋转、挥舞、变距运动,发展了一种运动嵌套网格。针对嵌套网格中关键的贡献单元搜寻问题,提出了一种新的“伪贡献单元搜寻法”。应用上述方法,对Caradonna模型旋翼在周期变距和挥舞运动条件下的前飞流场进行了计算,与采用Jameson二阶中心差分方法相比,计算结果更贴近实验值。并针对几种不同桨尖形状的旋翼前飞流场进行计算,表明后掠桨尖可有效减弱超临界流动。A Reynolds-average NS solver has been developed for the prediction of 3-D unsteady flow phenomena that occur on helicopter rotors in forward flight. For the solution of NS equations the combination of the third-order upwind scheme （MUSCL） and flux-differenco splitting scheme without adding artificial viscosity has been employed. As a result, the method can reduce the false dissipation of the rotor wake vorticity effectively when compared to Jameson＇s second-order cell-centered finite volume approach. To incorporate the important effects of the rotor wake and account for the rigid blade motions in rotation, flapping and pitching, a moving embedded grids methodology has been adopted. Aiming at the key identification issue of donor elements in embedded grids, the present analysis implements a new searching scheme, the Pseu-do-Searehing Scheme of Donor Elements （PSSDE）, for improvement purposes. As numerical examples, simulation results on surface pressure distributions are presented for a two-bladed Caradonna model rotor in forward flight at different.pitching and flapping angles. Better agreements are found with measurements or other calculated results contrast with the second-order center-difference scheme. Also, unsteady lifting results, simulated for three different blade-tip planforms, are given and the benefit of swept tips in suppressing supercritical flow is demonstrated.

关 键 词：旋翼 直升机 逆风格式 通量差分裂格式 运动嵌套网格 

分 类 号：V212.4[航空宇航科学与技术—航空宇航推进理论与工程]