Research On Numerical Virtual Flight Technology Of Low-speed Aircraft

Compared with flight test and wind tunnel-based virtual flight,numerical virtual flight（NVF）has the advantage of shortening the aircraft development cycle,reducing aircraft development costs and flight test safety risks.This paper studies the NVF technology of low-speed aircraft.The main research contents are as follows:Firstly,the finite volume method is used to discretize the flow field control equations in space,and the second-order backward difference discretization method is used to discretize this governing equation in time,and parallel calculation is used to accelerate the numerical simulation.The RKF45 method is used to solve the aircraft’s six-degree-of-freedom motion equation.Then,in order to control the movement of aircraft components,a control solution module was established.The dynamic overset grid technology and two grid update methods are used to realize the position update of the aircraft’s overall overset grid and the aircraft component overset grid,and the loose coupling method is used to realize NVF based on CFD coupled aerodynamics/motion/control disciplines.Secondly,the steady simulation of the NACA0012 two-dimensional airfoil and the M6 three-dimensional airfoil and the unsteady simulation of the NACA0012 two-dimensional airfoil pitching oscillation along the leading edge verify the effectiveness of the numerical calculation algorithm for the flow field of the low-speed aircraft.The simulation of the free-falling motion of the small ball and the rotating motion of the cylinder verifies the effectiveness of the algorithm for solving the low-speed aircraft motion.The simulation of the combined movement of the cylinder and the rectangular parallelepiped verifies the effectiveness of the mesh update algorithm.The simulation of the projectile with initial velocity flying forward under the action of gravity in the flow field verifies the effectiveness of the coupling algorithm.Finally,the two-dimensional wing is deflection controlled by proportional-integralderivative（PID）,the propeller is controlled to rotate,and the aircraft motion in space is simulated.The simulation results can reflect that the controlled motion causes the flow field sequence change and the multidisciplinary coupling effect.