четверг, 29 июня 2017 г.

Lowering aircraft emissions with next-generation engines

EU-funded researchers are pushing the limits of modern aircraft engine technology, developing ultra-efficient turbofans to cut CO2 emissions and reduce aircraft noise in order to meet ambitious environmental objectives over the coming years.
Bringing together 35 partners from 10 countries, the ENOVAL project is one of a family of European research initiatives aimed at cutting aircraft fuel consumption, emissions and noise. In combination, these initiatives provide the basis for the next generation of passenger aircraft engines that will meet or surpass the environmental goals set by the Advisory Council for Aviation Research and Innovation in Europe, including reducing aircraft CO2 and noise emissions per passenger kilometre by at least half from 2000 levels.
“ENOVAL is a key part of efforts to lower the environmental impact of aviation through innovative propulsion technologies that should enter into service from 2025 onwards,” says Edgar Merkl, the project coordinator at MTU Aero Engines in Germany.
Through uniting the expertise of leading engine manufacturers, component-makers and research institutes, the ENOVAL project is developing and validating improved designs for the fan modules of ducted geared turbofan engines that use ultra-high bypass ratio systems to increase thrust and lower fuel burn. Bypass ratio, or BPR, refers to the ratio between the mass flow rate of air drawn through the fan that bypasses the engine core compared with the mass flow rate of air combusted with fuel in the engine core. While current high-bypass aircraft engines have a ratio of up to 12:1, designs under investigation in ENOVAL should increase that up to 20:1, providing significant efficiency gains.
To reach such ultra-high bypass ratios, the ENOVAL team is working on a substantial increase in the diameter of the fan, which would also feature advanced fan blades optimised in number, shape and weight. A gearing system would enable fan rotation to be slowed to ensure peak performance at different stages of flight, while a variable-area fan nozzle will improve stability and performance.
At the same time, the researchers are also applying innovative designs and alternative materials to reduce weight and overcome the increased drag of a larger fan diameter.
“There is always a trade-off with any modification: any increase in the size or weight of a component needs to be compensated in order to produce a net positive impact,” Merkl explains.
Due for testing
The ENOVAL technologies are due to be tested and validated using 18 mechanical and aero-acoustic rigs in order to bring them up to Technology Readiness Level 5, three grades short of being ready for commercial deployment. At that point, the researchers expect to be able to demonstrate a 5 %reduction in CO2 emissions in long-range applications and a 3 %reduction during short-haul flights from the improved fan module technology alone. Taken in combination with other engine enhancements expected or achieved to date, that will represent a combined 24 %to 26 %reduction in CO2 emissions compared to year 2000 reference engines.
In addition, the project team estimates that by slowing the fan’s rate of rotation, the effective perceived noise level will be reduced by 1.3 decibels, accumulating a decline of nine decibels compared to year 2000 technologies and contributing to a significant decrease in noise pollution around increasingly busy airports.
The efficiency, noise and emissions improvements promised by ENOVAL tie in closely with advances being made by other projects funded under the European Commission’s FP7 programme, including LEMCOTEC for engine core efficiency, E-BREAK for component and sub-system technologies and OPENAIR for noise reduction.
“Together, this family of projects is pushing the very boundaries of what is achievable with current engine designs,” Merkl says. “They will result in the next generation of turbofan engines, providing significant efficiency gains for decades to come, but totally new technologies, including the use of alternative fuels, will likely be required to lower emissions beyond that point.”
Project detail
  • Project acronym: ENOVAL
  • Participants: Germany (Coordinator), Italy, UK, Spain, France, Sweden, Belgium, Russia, Austria, Netherlands
  • Project N°: 604999
  • Total costs: € 45 043 663
  • EU contribution: € 26 459 215
  • Duration: October 2013 - September 2017
Project website: