On-design and off-design operation performance assessmentsof an aero turboprop engine used on unmanned aerial vehicles (UAVs) in terms of aviation, thermodynamic, environmental and sustainability perspectives

In this study, a turboprop engine (TPE) of an unmanned aerial vehicle (UAV) is investigated for "on-design" and "off-design" conditions at maximum operation mode. One project point is chosen for on-design case for the cycle analysis. Other constraints and requirements are considered at off-design analysis in which cycle analysis is not affected. The off-design condition is generally used in emergency situation such as one-engine take-off, extreme flight speed, extreme altitude, and hot day operation. The aviation, energy, exergy, environmental, and sustainability analyses are performed to the TPE. For on-design and off-design conditions of the UAV TPE, the specific fuel consumptions are 0.287 kg/kW h and 0.282 kg/kW h, specific powers are 0.067 kW h/kg and 0.069 kW h/kg, thermal limiting ratios are 3.735 and 3.785, entalphy ratios are 4.482 and 4.555, energy efficiencies are 29.067% and 29.652%, exergy efficiencies are 27.38% and 27.93%, exergetic improvement potentials are 159.26 kW and 182.23 kW, ecological objective functions are -436.366 kW and -488.78 kW, environmental effect factors are 2.652 and 2.580, ecological effect factors are 3.652 and 3.580, exergetic sustainability indexes are 0.38 and 0.39, sustainable efficiency factors are 1.38 and 1.39, respectively. The results show that off-design condition has better fuel consumption, power, efficiency, improvement potential, environmental damage and sustainability than on-design condition. Also, the combustion chamber is the first component to be handled for the improvement of the overall system. UAVs are used for very deligant and important duties and their efficiency and sustainability play important role for their missions. UAV engines such as TPEs are the major power units to operate the overall system. Even a slight increase in efficiency and sustainability for the TPE engine can cause important feedback for the UAV mission. It is also important to assess the TPE for its environmental effects, because UAVs will play important role in the future for the transportation. As a result, this study is useful to assess turboprop engines of unmanned aerial vehicles in efficiency, sustainability and environmental aspects.