The basic problem addressed in this research is reducing noise pollution caused by machinery in modern societies.
Along these lines, Aircraft noise is the most significant cause of adverse community reaction related to the operation and expansion of airports.
Therefore, limiting or reducing the number of people affected by significant aircraft noise is one of the most important tasks of modern civil aviation. This has motivated much research in active noise cancellation both in the EU and US.
The present research effort deals with development of a novel noise cancellation method based on deposition of non-mechanical thermo-acoustic transducer (Thermophone) directly at a source of noise in an aircraft engine.
Noise reduction via sound cancellation is a trending mechanism for diminishing acoustic pollution in a multitude of sectors, including aviation, energy generation, transportation, military applications and elsewhere.
Such systems use local annihilation of an unwanted acoustic pressure field through the creation of an out-of-phase sound wave at the same amplitude and frequency, actively modulated in a control circuit according to the unwanted sounds as detected by sensing elements.
This typically involves an array of loudspeakers, which convert electric power into acoustic energy through vibro-mechanics. This solution works well in a limited number of clearly localized and defined situations, but the geometric limitations of conventional loudspeakers prevent the effective use of these anti-phase pressure emitters from being used in a distributed manner. Therefore, the common implementation of prior art noise cancellation is generally localized to the observer, rather than providing an overall elimination or reduction at the source.
Overall objectives are creating a physical model which enables to overcome current knowledge gap in Thermophone performance, establishing guidelines for selecting adequate materials and manufacturing processes for Thermophones, and demonstrating active noise cancellation on exemplary ducted fan, like the once used in civil aviation.
