Economic growth of airline markets has been the major factor for greater demand for air travel.
Aircraft noise remains one of the greatest barriers to airport expansion and new airport construction around the world. The US General Accounting Office (GAO, 2000a) has reported noise as the greatest environmental concern for the busiest US airports.
Aircraft noise is from four sources: engine, propulsion and airframe interactions, high-lift devices andlanding gear. There is not much change in the engine noise during take-off and landing, however, the airframe noise is significantly higher during landing compared to take off. You can find detailed information about our research related to noise in our Green Aviation Booklet.
Fractal grid spoilers
Spoilers are deployed during aircraft landing and act to reduce lift and increase drag. The contribution of spoilers and other control surfaces to the overall noise produced by an aircraft during landing is an important issue. Fractal spoilers are a new concept that has been very recently introduced by the Department of Aeronautics at Imperial College London. It has already been demonstrated that such devices can reduce noise by up to 4dB (relative to conventional spoilers) while preserving the main lift and drag characteristics required of a spoiler.
Supressing combustion and thermo-acoustic instabilities
The development of low NOx, reduced-noise combustors for aero engines is limited by the problem of combustion instabilities. Models developed in the Department of Aeronautics at Imperial College London match well to experimental results and can monitor fuel flow rate and combustion instabilities. The next steps are to extend these models to investigate adaptive control approaches, automatically tracking any changes in operating conditions of the engine, to take into account more realistic flame models.
Modelling of noise around airports
The effect of aircraft operations on the noise climate around airports can be determined through monitoring and modelling. Noise monitoring is excessively costly due to huge arrays of noise monitors that will have to be employed to measure aircraft noise. For this reason aircraft noise models have been developed at Imperial which can accurately predict sound propagation as an aircraft passes over housing on its approach to an airport.