Six degrees of freedom flight simulation of tilt-rotor aircraft with nacelle conversion

摘要

This paper presents six degrees of freedom flight simulation with mode conversion between airplane mode and helicopter mode as an application for realizing Digital Flight of the tiltrotor aircraft. The tiltrotor aircraft has the characteristics of both helicopters and propeller planes with changing the flight mode by tilting the engine nacelles. However, much less work with continuously changing these modes has been done so far. In this paper, the main components such as rotors, engine nacelles, fixed wings and a fuselage are considered. In order to perform large deformations of mesh geometry such as the rotation of the rotor and nacelle as well as the change of the position and attitude of the aircraft, the computational domain is decomposed into multiple domains corresponding to each component. Independently moving these domains makes possible to perform the characteristic behavior of a tiltrotor aircraft. To deal with rotations of multiple decomposed domains, the multi-axis sliding mesh approach is applied. As the solver for simulating unsteady flow driven by complicated moving boundaries, the unstructured Moving-Grid Finite-Volume method is adopted. Based on this solver, the Moving Computational Domain method enables the aircraft to fly in any size of region without restriction of mesh size. The airframe is treated as a rigid body, and the coupled simulations considering interaction with surrounding fluid of the aircraft are demonstrated. The result shows complicated fluid phenomena around the tiltrotor aircraft that occur when it flies with mode change. (C) 2020 Elsevier B.V. All rights reserved.