Second Law Analysis of an Experimental Micro Turbojet Engine

Mini class gas turbine engines are today used for small UAVs, cogeneration applications, and hybrid electric vehicle applications. In this paper, exergetic assessment of an indigenous mini class gas turbine engine is investigated. This engine is classified as mini class gas turbine where it differs from similar class engines in two ways, including closed loop lubrication system and bearing damping. A great amount of bench testing studies with required extensive instrumentation were also performed to demonstrate the suitability of this technology. Consequently, an approach in order to evaluate test data parameters for the exergetic performance is presented for mini class gas turbine engines used for small experimental planes and small-scale UAVs by applying the energy and exergy analyses to the engine. Hence, exergetic efficiency, improvement potentials, exergy destruction rates, relative exergy destructions, fuel depletion ratios, productivity lacks, and fuel and product exergy factors are calculated for the engine taking into account only dry air. This study shows that main exergy destruction for a typical gas turbine occurs in the combustion chamber. Exergetic efficiencies for centrifugal compressor, combustion chamber, and high-pressure turbine are found to be as 74.04%, 56.06%, and 98.98%, respectively. Finally, it was flight tested several times on small-scale UAVs and small experimental aircrafts with success.