Influence investigation of engine exhaust on aerodynamic performance for the flying wing UAV

The turbofan engine exhaust simulation is carries out for the flying wing UAV by the means of computational fluid dynamics. Firstly, the grid convergence study is performed with course, medium, and fine grid systems for the flying wing UAV through Reynolds-averaged Navier-Stokes equations and structured grid technology. Secondly, the change of the aerodynamic performance caused by the difference between the flying wing configuration with engine exhaust and without engine exhaust is discussed in the engineering design. Lastly, the turbofan engine exhaust effect is studied with three different nozzle pressure ratio conditions. The study shows that, the change of the configuration generated by engine exhaust makes the drag increased 6%-9% and pitching moment decreases. The engine exhaust has an effect on drag coefficient and pitching moment coefficient, and the influence quantities are varied with the nozzle pressure ratio.