successful program completion: enoval achieves its objectives


February 28, 2019

For almost five years, 35 partners conducted extensive research work under the EU’s ENOVAL (ENgine mOdule VALidators) technology programme. The result of the concerted efforts is now available: With the newly developed technologies for turbofan engines, it will be possible to significantly cut emissions of carbon dioxide and of noise. “We’ve fully achieved the objectives we had in mind when we started,” says MTU Aero Engines’ Dr Edgar Merkl, who coordinated the technology program, “and clearly demonstrated how much additional potential still exists in turbofans.” The new technology is slated to fly starting in 2025.

ENOVAL focused on the development of new technologies for low-pressure components for medium-sized, large and very large turbofans incorporating geared turbofan technology. The research looked into higher overall pressure ratios of between 50:1 and 70:1, as well as higher bypass ratios of between 12:1 and 20:1 combined with increased overall pressure ratios of up to 70:1. Says Merkl: “The bypass ratio achieved in the ENOVAL programme was in the range of 14:1 to 16:1.” This results in improved propulsion efficiency, thus reducing fuel burn and pollutant emissions. “And, on top of that, this will bring the noise emitted by emerging engines down further, even below the noise level of the geared turbofan, which is already very quiet as it is now.” Just look at some of the figures: Noise can be cut by up to 1.3 dB and CO2 emissions by up to five percent. For a typical medium-range aircraft, such as an Airbus A320, this would translate into savings of 1,200 tons of CO2 a year, the equivalent of the carbon dioxide emissions produced annually by electricity use in 325 average households.

The new engine component technologies for the fan, nacelle, gearbox, low-pressure compressor, low-pressure turbine and low-pressure shaft and for casings were developed by the ENOVAL partners – aviation companies, research institutes and universities from ten European countries. 18 rigs were set up and tested successfully, a number of patent applications filed, and the results reported in around 50 publications and compiled in ten learning modules, which have been made available on the ENOVAL website at The work was conducted on the basis of an integral approach, where the research did not just look at the individual components, but likewise took the interactions and mutual effects into account.

ENOVAL rounds off the EU’s roadmap of level 2 aero engine programs (component validation) under the EU’s Seventh Framework Programme (FP7), building on its two level 2 predecessor programs, LEMCOTEC and E-BREAK. “If you take a year-2000 engine as the baseline, ENOVAL technologies, combined with those resulting from the predecessor projects, allow us to cut noise by as much as nine decibels and, depending on the application, reduce CO2 emission by 20 to almost 40 percent,” explains ENOVAL Chief Engineer Dr. Jörg Sieber, who also works at MTU. According to Sieber, these values already meet ACARE’s targets for the year 2020 in terms of CO2 emissions.

Whereas the aim of LEMCOTEC and E-BREAK was, first, to develop technologies that increase the overall pressure ratio, and hence thermal efficiency, and, second, to adapt materials and subsystems so that they are capable of withstanding the pressures and temperatures that will increase in future, ENOVAL focused on the development of the low-pressure system for ultra-high bypass ratio aero engines. Bypass ratios larger than 12:1 being referred to as ultra-high bypass ratios (UHBRs).

The “tremendous interdisciplinary cooperation” was spurred by the high significance of the technologies, says Merkl: “All of the partners were aware of the vital importance of the new technologies for the future. Today already, they are part of the concepts developed by all engine manufacturers,” Merkl continues. The results presented again underlined the advantages of geared turbofan technology. “Given the benefits of a geared configuration in terms of overall efficiency, all competitors now tend towards this type of construction,” according to Merkl.