Fraunhofer at the Paris Air Show 2015 – Setting the Course for ‘Green Aviation’

Le Bourget, June 15, 2015: Fraunhofer, Europe’s largest application-oriented research organization, used this year’s Paris Air Show to up new vistas in order to reduce the environmental impact of aviation through innovation. The following report gives an overview on some key activities shown in Le Bourget.

The “Aviation Energy Efficiency and Climate Protection Report 2014” published by the German Aviation Association (BDL) states that 700 million tons of CO2 were emitted due to global air travel in 2013. If no action is taken apart from upgrading fleets and increasing the passenger load factor, the report warns that this figure could rise to 1,226 million tons by 2030. To avoid this happening, experts are increasingly focusing on the ecological aspects of air travel as well as the economic issues. One factor that has an impact on emissions is the aircraft cabin environment.

The 18,000 – odd passenger planes currently in operation worldwide not only seek to get their customers to their destination quickly, safely and in the most energy-efficient manner possible, they also want to make the time passengers spend in the air as pleasant as can be. Working within the framework of various programs – including the European “Clean Sky” technology initiative – the Fraunhofer Institute for Building Physics IBP is working with other Fraunhofer Institutes and industry partners to find ways of creating energy – efficient, clean and comfortable aircraft cabin environments. Researchers at Fraunhofer IBP are also investigating how to model and optimize the thermal management of electric aircraft components, an issue that is becoming more pressing as the development of more-electric and all-electric aircraft picks up speed.

“Flying is not only a luxury; an increasingly globalized society means aviation is more and more in competitive demand. That’s why it’s crucial to take an ‘ecolonomic’ approach to technology development by considering both ecological and economic factors. With this in mind, the Fraunhofer Institute for Building Physics IBP is also working on new aircraft architectures to make them more environmentally friendly while maximizing comfort and performance for passengers,” says John Cullen Simpson, General Director Aviation of the Fraunhofer-Gesellschaft.


Flight testing on the ground – the Ground Thermal Test Bench

One ecolonomical approach at trial in aviation industry, literally a hot topic for more use in modern aircraft, is the ‘all – electric’ design. This involves electrical systems to replace hydraulic means in aircraft functions. At the same time, efforts are being made to promote the use of lightweight materials in the development of new aircraft, reducing weight in order to cut fuel consumption. Fraunhofer IBP recently added another unique test laboratory to its facilities that will help scientists develop, validate and ultimately demonstrate the workability of these designs and the associated energy management concepts. The “Ground Thermal Test Bench (GTTB)” has enabled Fraunhofer IBP and its industry partners to expand the scope of their research activities.

The GTTB plays a key role in the simulation and testing of new systems with regard to thermal behavior, allowing a wide range of thermal measurements to be conducted on a genuine aircraft fuselage split into the three main sections of cockpit, cabin and empennage. Different structures, such as a helicopter cabin, can also be used in place of the aircraft fuselage. The test facility also includes the AirCraft Calorimeter (ACC) that simulates extreme conditions such as rapid decompression and thermal shock, in other words extremely rapid changes in temperature that can be caused by incidents such as damage to the cabin shell during the flight. “The test bench was developed as part of the European Clean Sky initiative and is capable of simulating conditions both inside and outside the aircraft – the same conditions you would experience during flight or on the ground,” says Markus Siede, responsible manager for the GTTB. The benefits offered by the GTTB are huge: by reducing the number of real-life test flights it cuts costs while simultaneously protecting the environment. (At this year’s Paris Air Show, Fraunhofer IBP has shown an in – depth animation explaining how the GTTB was created and what kind of tests it can be used for.)


Localized air conditioning with a vortex ring effect

Scientists at Fraunhofer IBP are also conducting major research into the environmental conditions inside aircraft cabins. On passenger flights, air humidity is generally kept very low to avoid problems with condensation on the outer skin of the aircraft. This can lead to passengers complaining of discomfort. Although it is unfeasible to raise the air humidity throughout the aircraft, experts are keen to find ways of improving air quality in passengers’ individual breathing zones. That requires a method of bringing pre-conditioned air with high moisture content directly to each passenger without implementing a generalized increase in air humidity through mixing ventilation. Researchers are hoping they can create this kind of personalized aircraft cabin environment by using what is known as the vortex ring effect. Using a linear motor, the scientists move a piston very rapidly in a cylinder. This forces air through a circular opening so that it emerges as a vortex ring and collides with the passenger’s chest area before being breathed in. Thanks to the natural convection around the passenger’s body, the vortex is barely perceived as a flow of air in the chest area and is simply transported to the breathing zone by the ascending layer of air. Research is currently focusing on the technical formation of stable vortex rings, the distance the rings can be projected, the effects of interfering air currents, and the type and method of continuous air conditioning at the air source. (Visitors to the exhibition booth in Paris could witness examples of this kind of vortex rings created using smoke.) The next stage of the Fraunhofer IBP development process is to add moisture to the air and closely measure the impact this has on passengers.


Aviation – a broad field of research at Fraunhofer IBP

Fraunhofer IBP is also drawing on its expertise in the core fields of acoustics, building chemistry, building biology, hygiene, life cycle engineering and indoor climates to assist in the “Clean Sky 2” European technology initiative, the follow-on program to “Clean Sky”. In recent years, Fraunhofer IBP’s research and development work in the aviation arena has made major use of the integrated technology demonstrator (ITD) eco DESIGN®”. The institute runs a unique Flight Test Facility (FTF) at its site in Valley near Holzkirchen. This consists of a low-pressure chamber housing the front section of a real aircraft segment that is approximately 15 meters long with space for up to 80 test subjects. As well as using the FTF to investigate cabin air quality, the researchers also conduct studies of aircraft as complete systems by investigating the energy aspects and usage requirements of areas such as the cockpit, passenger cabin, avionics and cargo bay.

One of the key areas of research is the aircraft cabin environment, which is a frequent source of passenger complaints. As well as using human test subjects, the researchers also rely on feedback from test dummies. The DressMAN 2.0 climate measuring system was specially developed by Fraunhofer IBP to monitor the indoor climate in aircraft, vehicles and offices. An innovative sensor developed by the Fraunhofer researchers enables them to determine the equivalent temperature”, in other words the homogeneous temperature of the intended space with an air speed equal to zero in which a person emits the same dry heat through radiation and convection as they would in the real -life environment without uniform conditions. This enables the scientists to express thermal environmental conditions as a single numerical value known as the climate index, opening up the opportunity to run comparative assessments of different climate scenarios with the ultimate goal of optimizing the indoor climate.

In order to provide a next-generation low-noise solution for the high lift devices, the researchers of the department Acoustics have designed a full – span droop nose (DN) wing configuration for the future geared turbofan aircraft. High aerodynamic and aeroacoustic performance of this configuration has been proved both in a wind tunnel test (WTT) campaign and in Computational Fluid Dynamics (CFD) and Computational Aero-Acoustics(CAA) analysis. Mechanical feasibility and extended environmental loads have been verified by a full-scale DN demonstrator. The scientists have also contributed to low – noise treatment of landing gears (LG) on new generation regional aircraft. The main LG bay configuration has been optimized based on the measurement with an acoustic beamforming system. Effectiveness of a hub cap low – noise solution for the nose LG has been verified both in WTT and in CFD/CAA analysis.

Another key ecolonomic aspect is the ongoing development of the eco DESIGN® Tool ENDAMI. Although the methodology Life Cycle Assessments (LCAs) isalready common practice in most industry sectors, the aviation industry still has development potential. An LCA is a recognized and standardized method of systematically evaluating all environmental aspects of a product through all the various stages of its life cycle, from raw material extraction, production and use until its recycling or disposal. As part of the European “Clean Sky” research program, Fraunhofer IBP and its project partners developed the eco DESIGN®tool ENDAMI with the goal of giving planners and designers easier access to LCA data and, crucially, direct and real-time feedback on the environmental impact of their aircraft. ENDAMI offers aircraft manufacturers by simple means the modeling of multiple design variations of their aircraft and a variety of different technology design choices. They can then optimize these variants while keeping a close eye on environmental and LCA aspects in real-time.


Background information: From Clean Sky to Clean Sky 2

Mid-2014 saw the launch of Clean Sky 2, the second part of a major European research initiative in which Fraunhofer will play a continued key role. The European Commission and the private sector will together be providing a further budget of some 4 billion euros. The project is designed to complemen tthe objectives of Flightpath 2050, which sets out a vision for air travel and aviation in the year 2050. Clean Sky 2 also takes into account the new agenda for strategic research and innovation drawn up by the Advisory Council for Aeronautics Research in Europe (ACARE). Clean Sky 2 is a private public partnership established under the Council Regulation until the end of 2024. Further information can be found under the links,,


Added power for airplane galleys

The galleys inside airliners voraciously consume power – a vital yet limited resource in a plane. Additional power units may soon come to the rescue: housed inside trolley carts in the galleys, these units deliver both supplemental power and thus uncouple the power to the cabin and the kitchen from that which is supplied to the rest of the aircraft. This novel technology was a debut feature at the International Paris Air Show.

Airplanes are built for long life: their use typically spans several decades. Interior furnishings in the cabins get renovated many times over the lifetime of the aircraft, same as the galleys. This pattern, however, harbors a certain problem: obsolete equipment is replaced by new equipment that usually requires more power – be they high-performance galley appliances, or amenities like miniature TVs in each individual seat back rest. Yet an airplane’s available power – generated in-flight by the turbines – is a limited resource. An auxiliary power unit supplies requisite power during periods when the turbines are not running, such as when passengers board or disembark.
There’s another hitch: once you add subsequent electrical loads in the passenger section of the cabin, then the power system of the entire airplane has to be re-approved and reauthorized, because new devices could disrupt the power supply and in a worst case scenario, paralyze the whole system.


Additional power supply to the galleys

A supplemental power unit in each galley in the shape of a movable trolley cart provides power. Researchers at the ICT-IMM branch of the Fraunhofer Institute for Chemical Technology ICT engineered the system in joint collaboration with Diehl Aerospace GmbH and the German Aerospace Center DLR. “This new power source lets us eliminate the energy shortfall,” states Prof. Dr. Gunther Kolb, Department Head at ICT-IMM. The cart can even facilitate the approval process since it does not need new approval every time the airplane gets a retrofit or a face-lift: The power supplied to the galleys and cabins is autonomous of the power to the rest of the aircraft.


Reformer and fuel cell

For their clever innovation, the researchers relied on fuel cells: they not only generate power efficiently, but quietly as well. However, things are not that cut-and-dried when it comes to using fuel in mid-air. Because hydrogen can only be stored in containers pressurized to roughly 800 bar: a considerable risk in the airplane’s cargo hold. This also precludes combustible fluids, like gasoline. “We use propylene glycol,” Kolb reveals. There is a major advantage: it is a liquid substance, i.e., it requires no pressurized containers, becomes non-flammable when mixed with water and, in addition, it is non-toxic. Moreover, it is already being used in airplanes as a coolant and de-icing agent.

Propylene glycol consists of hydrogen, carbon and oxygen. A chemical system, the reformer, breaks down the liquid and extracts the hydrogen, which flows directly into the fuel cell and thus, energizes it. Since the carbon monoxide resulting from hydrogen production is not healthy for either the passengers and flight crew or for the fuel cell, the reformer transforms it into a non-toxic carbon dioxide. The system has its origins at Fraunhofer’s laboratories. The employees not only engineered the requisite catalysts that were available in it, they also made sure that the device would take up the least amount of a plane’s precious space. “In the current reformer, we successfully configured the components that break down the carbon monoxide in a way that saves 90 percent more space than with conventional technology,” Kolb affirms.

The research team has already produced a mock-up of the reformer – even the individual components are in place available. Over the next few months, these scientists will assemble and test the very first prototype.

Source: Fraunhofer-Gesellschaft