The EU has demanded greater efficiency from the aviation industry. Engineers have many ideas for achieving that, including radical new aircraft architectures and propulsion systems. Yet designers must first mathematically model their proposed changes. Any aviation project needs highly sophisticated modelling and simulation capability available throughout its duration. A previous EU project, VIVACE, developed a European standard simulation software intended for this kind of modelling, called PROOSIS.
PROOSIS for aircraft design
The EU-funded DEMOS project used PROOSIS for the design and optimisation of various advanced propulsion systems. DEMOS is part of the Innovative Aircraft Architecture technology stream of the EU’s Clean Sky 2, in the programme Airframe. The team investigated two new propulsion systems. First was a counter-rotating open rotor (CROR). This is a propeller with two rows of blades rotating in opposite directions. The rotor’s swept-back blades allow it to use a larger volume of air than comparable rotors. The rotor produces more thrust but uses 25-30 % less fuel than comparable alternatives. The second propulsion system is an ultra-high bypass ratio (UHBR) geared turbofan. A UHBR turbofan is like a conventional turbofan but with a bypass ratio greater than 15. The new design increases the amount of air drawn into an engine, improving propulsive efficiency. Engineers begin a novel design project with assumptions about performance and technology limits. As the analysis progresses, the assumptions may need updating, leading to a further design iteration. “In DEMOS,” says project technical lead, Alexios Alexiou, “we developed a single-step approach linking the thermodynamic and aerodynamic design disciplines. We also increased the level of integration to allow multidisciplinary assessments at aircraft level. “This enables rethnking and consistent design optimisation of novel propulsion systems.”
Using the new design framework, the team optimised a geared turbofan to minimise the amount of fuel burn. This lowers both CO2 emissions and fuel costs. The resulting design achieves a higher bypass ratio than current engines. Compared to conventional turbofan engines, the optimal DEMOS design could lead to fuel burn and CO2 reductions 18 % better than engines of 20 years ago. DEMOS also investigated key enabling sub-technologies that allow optimisation of CROR and UHBR during operation. These include a variable-area fan nozzle, a blade pitch control mechanism and power transmission gearboxes. The company that owns PROOSIS, Empresarios Agrupados Internacional, is also the lead partner of the DEMOS consortium. The company releases updates annually to keep the tool state of the art. Work in DEMOS led to several advanced modules being added to the software, giving new design functionality. “The developments in DEMOS provide a new capability for exploring the design space, and optimising performance, for virtually any future propulsion concept,” adds Alexiou. The new framework is robust, flexible, modular and extendable, which guarantees its long-term applicability to design simulation applications. “Thus, the developed tool is an ideal platform for collaborative work on assessing innovative engine configurations.” Following the success of DEMOS, the consortium has won further funding. A new project, UTOPEA, will develop the UHBR propulsion systems and assess their potential.
DEMOS, design, propulsion system, PROOSIS, aviation, modelling, aerodynamic, aircraft design