Thermophone - a novel heat transfer based approach to global TOnal Noise cancellation in aviation

ongoing

Limiting the number of people affected by significant aircraft noise is one of the most important tasks of modern civil aviation. Among different contributors, tonal noise is the most important due to regulatory definitions and its attenuation characteristics, with the largest contributor being the fan aero-acoustics. Current passive noise reduction methods alone are insufficient to conform with the increasingly stringent noise emission regulations. This motivates our research in active noise cancellation, based on creation of equal amplitude and frequency pressure waves, in opposite phase to the disturbance. Having identified that the actuator technology is the main hindrance against hardware implementation in flying platforms, we have been investigating a revolutionary technology based on a truly static and surface-deposited sound emitter (thermophone), which creates pressure fields by thermo-acoustic effects rather than the vibro-acoustics utilized by common speakers. Comprising of a periodically Joule heated electrically conductive thin layer, a highly efficient thermophone requires modeling of non-Fourier heat conduction in deposits. The project is divided into 4 multi-disciplinary objectives: 1. Derivation of accurate macro-scale heat conduction model, including non-Fourier effects 2. Developing thermophone performance model by analyzing thermo-acoustic effect 3. Optimization of performance by material and geometric selection, and by manufacturing processes 4. Demonstrating aero-acoustic fan noise cancelation via the thermo-acoustic effect created by static heat flux transducer In addition to the significance that this project will have to the field of aviation, I strongly believe that successful completion of each work package will provide dramatic improvements over the state of the arts in conduction heat transfer modelling, consumer electronics such as speakers, manufacturing methods for thermo-acoustic devices, and active aero-acoustic noise cancellation.