Experimental Testing and Optimization-Based Performance Modeling of a Microjet Engine

In this paper, experimental results for a JetCat P80 microjet engine mounted on the GUNT ET796 microscale testing facility are presented. The data set is initially used to verify trends in performance parameters, including thrust force, compressor pressure ratio, maximum temperature and fuel consumption. This study reveals that the available air and fuel mass flow measurements are not adequate for a thermodynamic analysis, and additional effects need to be considered. For the specific engine, a secondary air flow cools the combustion products before entering the turbine, while a portion of fuel flow is used for lubrication. These issues are included in the development of a computational model used for simulating the engine’s operation. To estimate temperatures and pressures after the combustion chamber, as well as the portion of air used for cooling, an additional control volume accounting for the mixing process is assumed. An optimization algorithm is incorporated to determine the air bleeding ratio as well as components’ isentropic efficiencies, which represent the design parameters. The objective is the minimization of the relative error between the measured and estimated thrust while the agreement of the corresponding values for the mass flow rate is imposed as a constraint. The study demonstrates how experimental testing combined with advanced thermodynamic modeling and optimization can enhance the understanding of microjet engines operation and performance characteristics.