Experimental and numerical investigations on the lateral stability of a rotorcraft in ground effect

该研究项目的目标是识别和表征影响旋翼系统飞行稳定性的不同参数，以及对地面涡旋系统的基本反馈机制进行空气动力学分析。需要澄清的基本问题是，在哪种连接中，回流或地面涡拓扑与飞机上的载荷有关，以及风的影响是否会导致配平转子上的非线性侧向力。通过改变运行参数(根部切断、推力、接地距离、转子倾斜)，具体设置不同的运行条件。通过激发不同的地面涡旋拓扑结构，还将研究它们与位置损失发生的关系。通过将模拟结果与实验结果进行比较，可以得出能够准确再现悬停飞行中旋翼尾迹的必要设置。此外，数值模拟可以超越实验使用的测量技术的限制来研究关于地面涡旋的细节。特别是，对瞬变力的时间回溯成为可能，这应该有助于澄清根本原因。此外，还可以洞察难以通过实验访问的区域，因此实验和模拟在这里理想地相辅相成。

The objectives of the research project are the identification and characterization of different parameters influencing the flight stability of rotor systems as well as the aerodynamic analysis of fundamental feedback mechanisms of the ground vortex system. The fundamental question to be clarified, is in which connection the recirculation or ground vortex topology is related to the loads on the aircraft and whether wind influences lead to a non-linear lateral force on the trimmed rotor. By varying the operating parameters (root cutout, thrust, ground separation, rotor inclination), different operating conditions are to be specifically set. By exciting different ground vortex topologies, their relationship to the occurrence of position loss will also be investigated. The comparison of the simulations with the experiment allows a statement about the necessary settings to be able to achieve an exact reproduction of the rotor wake in hover flight. Furthermore, the numerical simulations allow to investigate details about the ground vortex beyond the limitation of the experimentally used measurement techniques. In particular, temporal backtracking of transient forces becomes possible, which should help to clarify the fundamental causes. In addition, insight into areas that are difficult to access experimentally is made possible, so that experiment and simulation ideally complement each other here.