Computational fluid dynamics analysis of aerodynamic characteristics in long-endurance unmanned aerial vehicles.

Long-endurance unmanned aerial vehicles (UAVs) play an increasingly important role in various aspects of societal life. In response to the national emphasis on air force development, a study on the aerodynamic characteristics of long-endurance UAVs was conducted. This paper utilizes SolidWorks software to construct a geometric model based on the MQ-9 UAV, and a CFD method to establish a simulation model for UAV cruising flight. The aerodynamic coefficients, required thrust, and total mass during UAV cruise were calculated, and the variation of aerodynamic coefficients as airflow passes through the UAV was described. A comparative analysis was performed on the effects of different angles of attack, flight speeds, and flight altitudes on aerodynamic efficiency. The study results indicate that at an altitude of 10 km, with a 0° angle of attack, the UAV achieves a lift coefficient of 0.8888, a drag coefficient of 0.0679, and a lift-to-drag ratio of 13.0988. The required thrust is approximately 2236 N, and the total flight mass is approximately 3090 Kg. The angle of attack has the greatest impact on aerodynamic efficiency, followed by flight altitude, while flight speed has the least impact on aerodynamic performance. The lift-to-drag ratio initially increases sharply and then decreases rapidly with increasing angle of attack. It is recommended to control the angle of attack within the range of 0°-6°. The lift-to-drag ratio increases slowly with increasing flight speed, suggesting that the flight speed should be maintained near the maximum cruise speed. The lift-to-drag ratio generally decreases with increasing flight altitude, and it is recommended to maintain the flight altitude within the range of 9 km-11 km.