ACOCTIA · Active Control Of Cavity Tones In Aircrafts

Airframe noise is equal to or louder than engine noise during the landing approach of a commercial aircraft. With the growth of air traffic as well as the ever increasing level of urbanisation around most airports in Europe, the annoyance near airports is increasing, and the environmental concerns and noise certification regulations make the study of airframe noise an important research topic. The European Commission, within the Advisory Council for Aeronautics Research in Europe (ACARE) has set an ambitious environmental objective; a noise reduction target for the air traffic noise of 10 dB reduction per aircraft operation as the first 2020 goal (CALM 2007).Cavity noise is one of the most important airframe noises. When flow passes over a cavity or opening, due to vortex shedding at the upstream edge of the cavity, intensive tone noises may be generated. The tone noise generated in this way could be categorized as fluid-dynamic oscillation noise. However, at low flow speed depending on the geometry of the cavity, another type of tone noise due to fluid resonant oscillation within the cavity may occur.The objective of the proposed IEF project focuses on the source noise reduction of airframe noise due to the landing gear cavities; specifically the cavity tones produced as a result of a fluid-dynamic or fluid-resonant oscillation, with the aim to generate solutions that will bring improvement towards the ACARE objectives. The goal will be achieved by consolidating and linking the state-of-art in the field and by implementing hybrid passive/active strategies.