Bauhaus Luftfahrt Details Concept Piston-Turbofan Engine

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Munich-based Bauhaus Luftfahrt recently presented a composite concept engine design at ILA Berlin that incorporates piston engines into a conventional turbo engine design. (Photo courtesy of Bauhaus Luftfahrt.)

Aerospace research company Bauhaus Luftfahrt showed off some cutting-edge technological concepts at its booth during the ILA Berlin aerospace industry trade event in late April. Perhaps chief among them was the Munich-based company’s hybrid propulsion concept, which it refers to as the Composite Cycle Engine, or CCE. Bauhaus Luftfahrt says the CCE “incorporates piston engines into the core of an aircraft turbo engine.” Early estimates from Bauhaus Luftfahrt suggest the engine could be available by 2050 with the potential to significantly reduce fuel burn.

Up To 50%

In a news release promoting the concept, Bauhaus Luftfahrt, which refers to itself as “the futurologists,” explains that by using non-stationary isochoric-isobaric combustion, piston engines enhance thermal efficiency, thus enabling higher peak pressures and temperatures within the engine’s core. A current design for the company’s concept entails a piston engine connected with a high-pressure spool and powering an axial-radial high-pressure compressor.

“The low-pressure system is similar to a conventional geared turbofan architecture,” the company explains. “This way, the outstanding power-to-weight ratio of low-pressure turbines can be fully utilized and an ultra-high bypass ratio is realized.” If the engine enters service by 2050, Bauhaus Luftfahrt states “fuel burn improvements up to 50% relative to year 2000 turbofan technology (11% relative to year 2050 advanced GTF [geared turbofan] technology, respectively) can be reached.”

Targeting Engine Efficiency

Based on illustrations and information from Bauhaus Luftfahrt’s website, the concept engine’s fan measures 9.4 feet (2.87 meters) in diameter, while the entire engine stretches 19.3 feet (5.88 meters) long and weighs 2.45 tons (2.2 metric tons). Additionally, the engine incorporates 16 fan blades and 20 pistons.

Also on its website, Bauhaus Luftfahrt notes that while the concept resembles a conventional turbofan architecture at first glance, the piston system replaces the high-pressure section and as such, “the lightweight turbo components provide engine thrust, pressurize the piston system, and extract the energy from the core-engine flow.” The piston system, the company notes, “tops the turbo-engine cycle at pressures and temperatures unseen in turbofan engines.”

Bauhaus Luftfahrt indicates that the concept engine achieves peak pressure ratios of more than 300-to-1 vs. roughly 60-to-1 for advanced turbofan engines. “This reduces fuel consumption of the aircraft by 15%, allowing it to meet engine efficiency targets for year 2035, although engine weight increases by 30%,” the company notes. “The engine core size remains constant compared to a turbofan. NOx [oxides of nitrogen] emissions can also be reduced by 10%, compared to advanced lean-burn combustion technology.”

Source: Bauhaus Luftfahrt

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