Pokročilá aerodynamika výškových bezpilotných lietajúcich systémov (UAV)

Abstract

This article deals with the advanced aerodynamics of high-altitude long-endurance unmanned aerial vehicles (HALE UAVs). The aim of the work was to analyze the current knowledge in the field of stratospheric flights and, based on the obtained results, to design a theoretical model of an unmanned aerial vehicle capable of stratospheric flight for specialized applications. The thesis analyzes the specific conditions of stratospheric flight, including low air density, low Reynolds numbers, potential compressibility effects, and reduced control surface effectiveness. Existing HALE UAV systems (e.g., Helios, Zephyr, PHASA-35) and their aerodynamic challenges are examined. Within the scope of the work, a theoretical UAV model with a 10-meter wingspan, S1223 airfoil, and V-tail configuration was designed using Autodesk Inventor software. The aerodynamic performance of the designed model was verified using CFD simulation in ANSYS Fluent software for flight conditions at an altitude of 20 km (temperature 216.65 K, pressure 5.5 kPa, speed 25 m/s) employing the k-ω SST turbulence model and the NIST Real Gas model. The simulation demonstrated the model's ability to generate a lift of 512.5 N with a drag of 38.2 N, allowing it to carry a payload of approximately 12 kg with a total drone weight of 40.2 kg. The achieved L/D ratio is 13.42, confirming the good aerodynamic efficiency of the design for the given conditions. In conclusion, it is stated that stratospheric flight presents significant aerodynamic challenges mainly due to low air density, but the designed model demonstrated potential for specialized missions. Successful HALE UAV design requires a comprehensive and integrated approach combining aerodynamics, structures, materials, propulsion, and control systems.