Aerodynamic numerical simulation of four-axis vertical take-off and landing jet unmanned aerial vehicle

Based on the strict requirements of high maneuverability, high load and high dynamic response of unmanned vertical take-off and landing (VTOL) aircraft, a four-axis VTOL jet unmanned aerial vehicle (UAV) was researched and designed. According to the three basic equations of fluid mechanics and turbulence k−ε equation, the aerodynamic numerical simulation was carried out to determine the calculation domain of the external flow field during UAV flight. ICEM CFD software was used to divide the external flow field into hybrid unstructured grids. The flow field boundary conditions were set in the Fluent solver, and the turbulence model was taken as the basic model. The aerodynamic performance of the whole UAV were simulated and solved. The resistance coefficient, flow velocity distribution, pressure distribution and turbulent kinetic energy of each part of the UAV surface were obtained, and the aerodynamic characteristics were analyzed. The analysis shows that there are problems of large kinetic energy loss and high resistance coefficient at the top, tail, lower surface head and jet bracket of the upper surface of the UAV. According to the simulation results, the aerodynamic modeling of the above parts of the UAV was optimized. The results show that the total resistance coefficient of the UAV is reduced from the original 0.165 to 0.121, and the surface pressure, flow velocity and turbulence of the UAV are effectively improved. After optimization, the aerodynamic characteristics are better and the aerodynamic modeling is in line with the design concept.