This highly compact gas turbine airplane engine recirculates most of the post-combustion flow to join with air coming into the engine. The design increases engine performance and reduces the environmental impact of flight by limiting contrail formation. Contrails contribute to global warming more than CO2 emissions from planes; they form when water vapor condenses around soot from the exhaust. Recirculating part of the post-combustion flow can reduce contrail formation via water capture, soot suppression, and total exhaust flow reduction. Semi-closed cycle gas turbine engines have been demonstrated but not applied to airplanes. Normally the addition of a heat exchanger increases the engine weight significantly; however, semi-closed cycle engines provide the dual benefits of low weight and high efficiency, in addition to contrail suppression.
Researchers at the University of Florida have demonstrated a semi-closed cycle engine that employs a heat exchanger that operates at high pressures, allowing high overall engine compactness. The design enables the application of a semi-closed cycle gas turbine engine in airplanes.
Semi-closed gas turbine airplane engine that increases engine performance and limits contrail formation
This engine design for application in airplanes employs a semi-closed cycle that allows for capture of water vapor produced by combustion. The exhaust is nearly soot-free, which also reduces contrail formation, and the total exhaust flow is only one quarter of the normal flow. These three effects combine to produce a dramatic reduction in contrail formation. Further, the design improves engine performance and reduces the engine propulsion system weight as compared to conventional airplane engines.