Claire – Clean Air Engine

Claire – Clean Air Engine

In its Clean Air Engine (Claire) technology roadmap, MTU is combining key technologies into a commercial propulsion system that, by the year 2050, will burn 40 percent less fuel, will reduce CO2 emissions by the same amount, and will cut noise by 65 percent. Plans are to achieve the CO2 and noise targets defined by the European aviation industry and research community in the Strategic Research and Innovation Agenda (SRIA) in three stages.

15 percent, 25 percent, 40 percent less carbon dioxide-these are the staged goals of Claire. In the first stage, the geared turbofan engine alone already provides a reduction in fuel consumption and, hence, carbon dioxide emissions by up to 16 percent. Simultaneously, the aircraft's noise footprint is significantly reduced. Concept studies conducted as part of the second stage of Claire indicate that the geared turbofan configuration lends itself as a platform for further improvement. For example, it is quite conceivable that the fan pressure ratio can be further reduced and thus the bypass ratio further increased from 12:1 (geared turbofan) to up to 20:1 by the year 2030. Moreover, the thermal efficiency of the core engine can be enhanced by higher pressure ratios and temperatures. The aim is to increase the overall pressure ratio from currently almost 50:1 to 70:1 and at the same time appreciably reduce the amount of cooling air required.

In the third and last stage of Claire, major changes are envisaged that may well go beyond today's gas turbine technology. Jointly with universities and other research establishments, MTU is conducting studies for this phase. Among the options under review are the use of highly efficient heat engines with extremely high pressures or the embodiment of recuperative elements to improve the thermodynamic cycle process. Other conceivable concepts include shielded propellers or fans distributed around the fuselage.

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