Chief Engineer's Editorial - October 2008

[Begleittext / Subline: Joerg Sieber, NEWAC Chief Engineer ]

Commercial aviation has an impressive history of success, having become a means of mass transportation that carries in excess of 2 billion passengers a year. Breathtaking technological improvements have occurred in the past on economical and ecological fronts alike. Air traffic nonetheless faces novel challenges in the wake of diminishing energy supplies and worsening climate changes.

In the past, air traffic grew some 5% a year, and the outlook for the future is much the same (Fig. 1). Technological improvements have indeed appreciably reduced specific fuel consumption (per passenger kilometer), yet fast-paced traffic growth keeps increasing fuel consumption and hence CO2 emissions of the world's aircraft fleets by about 3% annually (Fig. 1).

[Begleittext / Subline: Fig. 1: Air traffic and CO2 emissions ]

Society expects the aviation industry to satisfy its continuously rising mobility needs while sparing the environment and resources. The European Union, for instance, has aimed to reduce CO2 emissions 20% by 2020, compared with 1990 levels. As it will become apparent from Fig. 1, however, the rate of past technological improvement will no longer be adequate to reach this goal.

A reduction of the CO2 emissions can be attained only if all stakeholders collaborate in the improvement of air traffic management, in the introduction of biofuels and the development of innovative airframe and engine technologies.

A large part of the necessary improvements will have to come from the engine industry, to a degree such that continuous improvement of engine components in itself will no longer be sufficient. That is why under the NEWAC technology project, novel engine cycles permitting quantum leap improvements are being explored and the necessary technologies are being developed. A highly promising approach, for instance, is the intercooled, recuperated engine configuration shown in Fig. 2, which is based on numerous novel technologies that are all being investigated under the NEWAC project.

[Begleittext / Subline: Fig. 2: NEWAC key technologies for new engine cycles ]

Most NEWAC activities focus on the compressor (Fig. 3), for which fundamentally novel approaches are pursued as well, such as improving the surge limit through tip injection, reducing clearance losses through active clearance control and increasing aerodynamic loading through aspiration on blades. These technologies can also find use on conventional engines.

[Begleittext / Subline: Fig. 3: NEWAC key technologies for compressors ]

As it will become apparent from Figs. 2 and 3, the individual technologies being developed by the various participating companies complement each other to form a coherent package. I am hopeful that by the time NEWAC draws to a close, we will be able to provide technologies to meet the requirements awaiting us down the road.