Study of Fuel-Controlled Aircraft Engine for Fuel-Powered Unmanned Aerial Vehicle: Energy Conversion Analysis and Optimization

Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UAVs), and it is directly determined by the power characteristics of the aircraft engine in the UAV. In this study, to prolong the flight duration and enhance the power and efficiency of a UAV, an aircraft engine is analyzed based on the fuel injection control system and output power characteristics. First, the mathematical model of a fuel-controlled engine is constructed. In addition, the experimental stations of the aircraft engine are set up to verify the mathematical model. Furthermore, the effects of key parameters on the engine power characteristics are examined. By the experimental and simulation studies validity of the mathematical model is effectively verified which indicates that the increased rotating speed decreases the power efficiency of the aircraft engine, and reducing the fuel injection pulse width from 5 ms to 3.5 ms increases the power efficiency by 10%. Moreover, increasing the advance angle of ignition from 10° to 40° improves the power efficiency by 5%. In addition, when the fuel injection delay width increases from 0.5 mm to 1.5 mm at an engine speed between 3500 rpm and 4000 rpm, the power efficiency is improved by 6%. Finally, when the engine speed is higher than 4000 rpm, increasing the propeller rotor diameter from 650 mm to 800 mm enhances the power efficiency of the aircraft engine by approximately 5%. This research can be considered as the fuel injection system optimization and cruising duration improvement of a fuel-powered UAV.