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

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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.