Periodic Reporting for period 2 - ThermoTON (Thermophone - a novel heat transfer based approach to global TOnal Noise cancellation in aviation)
Période du rapport: 2021-10-01 au 2023-03-31
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.
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.
Main finding in the period covered in this report provide an insight into the effect of properties such as heat conduction, density, layer thickness and heat capacity on Thermophone performance, and provides initial guidance towards more efficient Thermophones. Furthermore, we have proven that the ratio of thermal to kinetic energy of Thermophones corresponds to a theoretically derived value.
The analysis of data indicates that the ratio of thermal-to-kinetic powers corresponds to the theoretically derived value, after considering the thermal power split between the gas and the substrate, the ratio of acoustic sources’ powers correlates to the specific heat ratio γ of the surrounding media through γ⁄((γ-1) ) relation.
In conclusion, better fundamental insight into thermos-acoustically coupled thermal physics will contribute to the advancement of preexistent emitters, which can be developed into noise cancellation and sound generation applications.
Through an increased flexibility, this technology holds promise to yield superior performance of global on source noise cancellation capabilities.
The analysis of data indicates that the ratio of thermal-to-kinetic powers corresponds to the theoretically derived value, after considering the thermal power split between the gas and the substrate, the ratio of acoustic sources’ powers correlates to the specific heat ratio γ of the surrounding media through γ⁄((γ-1) ) relation.
In conclusion, better fundamental insight into thermos-acoustically coupled thermal physics will contribute to the advancement of preexistent emitters, which can be developed into noise cancellation and sound generation applications.
Through an increased flexibility, this technology holds promise to yield superior performance of global on source noise cancellation capabilities.
To this date, preliminary guidelines towards efficient thermos-acoustic transducers derived.
In addition to that, an evaluation of power split between thermal and kinetic energies can be calculated and advance the research in the field.
Along these lines, until the end of the project we are expecting to achieve active noise cancellation on a ducted fan.
This will be accomplished by improving current theoretical knowledge base in the field of Thermo-acoustics along with database on preferable materials and manufacturing methods of Thermophones.
Publications:
Band selection for mid-wave infrared thermography through extended radiometric calibration and heuristic-based optimization - 10.1016/j.measurement.2021.109242
Analytical and experimental demonstration of global noise cancellation between two co-planar thermo- and vibro-acoustic sources in varying gaseous media - https://doi.org/10.1016/j.jsv.2022.117431
Evaluation of the impact associated with various geometrical and material properties on the overall acoustic performance of generic multi-layer thermo-acoustic sources - submitted to journal of the acoustical society of America (JASA-08839)
In addition to that, an evaluation of power split between thermal and kinetic energies can be calculated and advance the research in the field.
Along these lines, until the end of the project we are expecting to achieve active noise cancellation on a ducted fan.
This will be accomplished by improving current theoretical knowledge base in the field of Thermo-acoustics along with database on preferable materials and manufacturing methods of Thermophones.
Publications:
Band selection for mid-wave infrared thermography through extended radiometric calibration and heuristic-based optimization - 10.1016/j.measurement.2021.109242
Analytical and experimental demonstration of global noise cancellation between two co-planar thermo- and vibro-acoustic sources in varying gaseous media - https://doi.org/10.1016/j.jsv.2022.117431
Evaluation of the impact associated with various geometrical and material properties on the overall acoustic performance of generic multi-layer thermo-acoustic sources - submitted to journal of the acoustical society of America (JASA-08839)