直升机旋翼非定常涡尾迹演化与相关气动特性的数值研究

Vortex wake evolution and related aerodynamic characteristic problem of unsteady flows around a rotor is a challenging task of the aerodynamics of the helicopter rotor for years, as well as a study focus of the aerospace industry and the scientific community. To overcome the limitation of recognization for the unsteady complicated flow field, the project will carry out numerical study on not only the physical mechanism of blade tip vortex formation and rotor wake evolution, also the influence of rotor wake on the rotor aerodynamic characteristics. Therefore, identification method for tip vortex and vortex sheet structures is to be detected. Meanwhile, advanced numerical methods including an adaptive grid technique, a new scheme with the property of resisting wake dissipation, and a high order overlapping grid interpolation method will be developed in this project. Based on these methods, the flow field of the helicopter rotor will be simulated. At the same time, the rotor vortex wake evolution and related aerodynamic characteristic is to be deeply discussed. The rotor wake geometry, the vortex core position and the variation of the wake vorticity strength during the wake transportation can be comprehensively analyzed. In addition, the structural characteristics of rotor wake and the related mechanical mechanism during the blade tip vortex formation and the wake transportation will be explored. Furthermore, the larger purpose of the project is to reveal the complicated phenomena and flow mechanism in the flow field around the helicopter rotor and thereby to provide the theoretical foundation for the development of helicopter rotor aerodynamics.

旋翼非定常流动的涡尾迹演化及相关气动力特性问题一直是直升机旋翼空气动力学的难题，也是航空工业界和科学界相关研究的热点。为突破旋翼非定常复杂涡流场认识的局限性，本项目将对旋翼桨尖涡尾迹的产生与发展演变过程的物理机理，及尾迹对旋翼气动力特性的影响进行数值模拟研究。旨在通过建立描述旋翼桨尖涡和涡切的物理参量标准，及发展先进的数值方法：涡自适应网格技术、一种新的抗涡尾迹耗散格式、高阶插值重叠网格方法，深入讨论旋翼涡流场中的尾迹演化过程和旋翼气动力特性，分析涡系几何结构、涡核位置和涡强度的可能影响，探索旋翼桨尖涡的发生、发展过程中尾迹结构特征与相关的力学机理，揭示旋翼流动的复杂现象及其流动机理，为推动直升机旋翼空气动力学的发展提供理论基础。

旋翼非定常流动的涡尾迹演化及相关气动力特性问题一直是直升机旋翼空气动力学的难题，也是航空工业界和科学界相关研究的热点。为突破旋翼非定常复杂涡流场认识的局限性，本项目对旋翼桨尖涡尾迹的产生与发展演变过程的物理机理，及尾迹对旋翼气动力特性的影响进行了数值模拟研究。为更准确捕捉复杂流场的流动细节，通过对WENO格式的光滑因子进行改进，发展了一种新的五阶WENO格式。研究了结构网格上的高精度WENO格式的构造，对一维双曲守恒律网格模板的选取、插值多项式的构造、精度进行了比较详细地分析和论证，然后推广到二维双曲守恒律。并对典型算例进行了计算，验证了格式对激波以及接触间断具有较高的分辨率。发展了一套适用于二维/三维、定常/非定常粘性流动的高效、高精度数值计算方法和计算程序。将改进WENO高精度格式应用于悬停旋翼绕流的数值模拟，发展了一种基于五阶迎风WENO格式的计算悬停旋翼流场的低耗散数值方法。基于改进的五阶WENO格式和运动重叠网格技术研究发展了适用于前飞直升机旋翼非定常粘性绕流的低耗散高精度数值计算方法。本项目研究在一定程度上能为推动直升机旋翼空气动力学的发展提供理论基础。