Supervision: Hervé Lissek
Project type:
Semester project (master)
Master thesis
Available
The Corona Discharge (CD) principle has been demonstrated to allow achieving linear acoustic flow velocity source without relying on an intermediate membrane, presenting an almost perfect electroacoustic transduction with an extremely sharp impulse response. The CD loudpeaker generally consists of two electrodes, a "corona" electrode of extremely thin size (array of wires, needles, etc.) put at a sufficiently high voltage to ionize the surrounding medium particles, and a "collector" electrode, conductor of larger size than the "corona" connected to the ground, attracting the ions while being sufficiently transparent to particle streams (eg. a metallic grid).
With this configuration, the CD loudspeaker presents a combination of two intrinsic sources: a monopolar "Heat" source, due to the local heat exchanges occurring in the ionization process, and a dipolar "Force" source, resulting from the electrostatic force accelerating the charged particles (and the surrounding medium) back and forth around the transducer. This transducer has been proven to be an ideal flow velocity source, and a recent PhD thesis proposed a detailed model of the transducer that can serve now for further optimization.
Besides the absence of membrane, this arrangement allows imagining various geometries that are not possible with membrane-based loudspeakers. However, the absence of membrane imposes a "high-pass" behaviour for this sound source in the far field, making it almost inneffective as a "direct-radiation" sound source.
The proposed semester project intends to work on identifying and eventually implementing CD loudspeaker configurations improving the sound radiation efficacy, especially presenting a meaningful band-pass behaviour over a relatively large frequency band in the audible range, and eventually improving the radiated sound power level of the source.
The project will consist in the development of a COMSOL (and/or analytical) model of the transducer, that will serve for geometry optimization. After defining a set of optimal geometries, one or several prototype(s) will be constructed and tested in anechoic conditions.
Content
- COMSOL and/or Matlab simulations
- Electroacoustic measurements
Prerequisite
- BA5-Electroacoustique
- or MA1-Audio Engineering