Optimization of working process parameters of small-scale turbojet for unmanned aircraft

This article describes the results of optimization of the working process parameters (overall pressure ratio and turbine inlet temperature) of small-scale turbojet for cruise missiles and target airplanes. The influence of engine scale factor upon the efficiency of turbomachines, as well as the principal operational constraints were taken into account during the multi-criteria optimization. Specific fuel consumption and the total mass of engine and required fuel were selected as the optimization criteria. Optimal regions of the working process parameters were identified for the turbojet engines of thrust ranging from 0.1 kN to 2 kN. The results show that different types of turbomachinery (e.g. axial vs. centrifugal compressor) have substantially different optimal regions, thus the stage of optimization of working process parameters for the small-scale engines could not be implemented independently, unlike the full-sized engines. According to results, the optimal values of working process parameters decrease as the engine scale factor decreases, and the optimal regions shrink too. The results presented in this paper also include the most efficient values of the working process parameters and the rational types of turbomachines for various thrust levels and aircraft missions.