Acoustic resonance prediction using a multiphysics model

Summary form only given. High intensity discharge lamps present several advantages over the other light sources (high lumen efficiency, important lifetime, large power range) that made them undeniable for urban lighting applications. Since their consumption represent a non negligible part of the total energy amount consumed on earth, improvement on their efficiency and supply is obviously investigated. However, their supply has always been considered as difficult and dangerous due to the acoustic resonance phenomenon that can cause arc instabilities, reduce lifetime and even lead to lamp destruction. To study these phenomena better, we have developed an experimental setup mixing electrical, optical and acoustics measurements for ceramic metal halides lamps. This enabled us to identify frequencies for which we have acoustic resonances. We then have noticed that the distortion of the arc appeared only for certain frequencies. This some times involves a change in the production of the lamp radiation, and a phenomenon of hysteresis appeared according to whether the frequency increase or decrease. We then developed a fluid model in three dimensions coupling the conservation of mass, momentum, energy and current. The results that we obtain are in perfect agreement with those given by the experimental data and allow us to better understand the various phenomena responsible for these resonances but also their effects and in particular the amplitude of the oscillations