A comparative Analysis and Optimization of two Supersonic Hybrid Solid Oxide Fuel Cell and Turbine-less Jet Engine Propulsion Systems for Unmanned Aerial Vehicles

The propulsion system of an Unmanned Aerial Vehicle (UAV) plays an essential role in its performance, stability, and flight endurance. In this work, two types of propulsion systems for UAVs (differentiated based on the fuel type) are studied in order to determine their characteristics and advantages. These proposed propulsion systems use a solid oxide fuel cell (SOFC) to generate the heat required for the operation of the turbine and generate thrust. In order to achieve the best operating condition, a multi-objective Non-Dominated Sorting Genetic Algorithm (NSGA-II) in MATLAB is used to decide the key design parameters. To reach the best conditions where the acceptable thrust is accompanied by a reasonable flight duration, the TOPSIS decision-making method is considered. The results obtained indicate that the efficiency and generated power of the propulsion system increase with a higher flight altitude or compressor pressure ratio. Also due to the recirculation of fuel in the SOFC's anode, a higher efficiency is observed in comparison to when hydrogen is used since anode-recirculation causes a higher fuel utilization. The optimization result shows that the efficiency and fuel consumption for the hydrogen-fueled system is48.7% and 0.0024g/s, respectively, and 67.9% and 0.0066kg/s for a methane-fueled engine. It is also found that the maximum efficiency for both the hydrogen- and methane-fueled systems are available with the stack temperature of 1025 K; however the maximum thrust for these systems is at the stack temperature of 1075 K. In addition, increasing the fuel rate of the SOFC power unit helps the process of generating extra power and thrust for UAVs.