"Effects of nocturnal aircraft noise on sleep " in the DLR-Project "Quiet Air Traffic I"

Description of the Project "Quiet Air Traffic"

In Germany, aircraft noise is one of the most urgent environmental problems and threatens to obstruct acceptance and further development of air traffic in the future.

Since the sixties, the number of aircraft passengers in German airports has increased to the sevenfold amount. Cargo and mail traffic has increased ninefold, and the greater part of this cargo is processed by night. The DLR in its function as the organisation responsible for aviation research in Germany is requested to work on this important problem area in its substantial aspects. The DLR is prepared especially well for this, as it is the only German research facility that commands the whole range of necessary disciplines and abilities.

In practice, only the effects of single noise-reducing measures have been examined up to this time. So far, a research of noise scenarios, effect patterns and purposefully structured counter measures in their entirety doesn't exist. Therefore, the DLR has been combining its existing abilities and activities in the fields of medicine, aero-acoustics, flight and engine technology, atmosphere physics, flight control and traffic research.

Within the project, the DLR institutes involved have the following aims of research: 

The  Department of Flight Physiology of the Institute of Aerospace Medicine examines the effects of nocturnal flight noise on humans in the largest study world-wide (four sleep facility studies and two field studies). You can find more about this study under the respective sections of this homepage. 

The Institute of Propulsion Technology compiles construction suggestions on lowering the fan noise in jet engines by a decrease of the peripheral speed and the noise-optimized hovel draft. Furthermore, procedures for the reduction of single frequencies of turbo-machine noise on the basis of active acoustic processes are being tested.The improvement of these procedures also requires the optimization of the methods used for the sound field analysis of the engines.

The Institute of Aerodynamics and Flow Technology is responsible for research concerning the reduction of noise caused by the surge flow of the plane. This area covers chassis noise, the uncovering of the mechanisms responsible for the production of tonal and broadband noise at the slat and at the landing flap side edge and the development of technologies for noise reduction in high lift systems, as well as the clarification of the effect mechanisms among other things. The wind tunnel measurements necessary for this are validated by flyovers in controlled conditions. 

The Institute of Flight Research and the Institute of Flight Guidance improve the flight procedures with respect to the influences of flight security, work strain of the pilots, passenger comfort and fuel consumption. These improved procedures will be assessed with regard to their noise reduction potential in view of reference procedures (computer simulation, flight tests for the clarification of flight-operational problems). An optimization of nocturnal aircraft traffic in particular is intended. Additionally, concept for the integration of modern air traffic management systems will be provided. 

The Institute of Air Transport and Airport Research will first provide an overview of the procedures planned or used in German and international airports. These procedures will then be examined with regard to airport-specific basic conditions and evaluated in respect of their potential for noise reduction, their effects on traffic and their subsequent economic effects. The criterium of valuation here is a high noise reduction potential with restrictions as low as possible in regard of traffic and economic development. On the basis of these results, new promising solutions will be conceived. 

The Institute of Aerodynamics and Flow Technology will develop an EDP-supported procedure for the determination of aircraft noise strain in the environment of civilian airports. The basis for this is the computational simulation of single flights and the modelling of the sound emission of the plane caused by partial acoustic sources. The model will be laid out in such a way that the results of the project "Quiet Air Traffic" concerning sound creation mechanisms and the sound propagation model can be integrated. The goal is to derive a simple computation method from this comprehensive simulation model which meets the requirements for a practicable, legally fixable model and is thus necessary - mainly in respect of the planned amendment of the Aircraft Noise Law. 

The Institute of Atmospheric Physics will develop a model system for the consistent simulation of the metereological and topographical influences on sound propagation. The model system consists of an existing metereological model and of an acoustic model which has yet to be developed. It is necessary for the acoustic model to describe the physics of sound propagation as exactly as possible, but at the same time it has to be economical in order to be practicable. For this reason, the development of the model will be executed in gradated complexity. The basics for the parameter setting will be tested on a physically extensive model and then be integrated into a practicable progonosis model. 

The overall Project "Quiet Air Traffic" has got its own homepage and the DLR is also part of the Research Network "Quiet Traffic".

Dr.rer.nat. Ullrich Isermann
German Aerospace Center

Institute of Aerodynamics and Flow Technology
, Helicopters
Tel: +49 551 709-2255

Fax: +49 551 709-2581

E-Mail: Ullrich.Isermann@dlr.de
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