Experimental and Simulated Straightening of Metal Halide Arcs Using Power Modulation

Years of research in the fundamentals of acoustically generated flows in high-intensity-discharge arc tubes for enhancement have recently produced record-breaking performance in converting wall-plug power to useful white light. In this paper, simulated results show how power modulation produces straightened arcs in horizontally running lamps. A fully unsteady compressible 2-D flow model is used to reproduce observed instantaneous pressure and temperature oscillations, and the results are time averaged and rendered to visualize the bulk gas flows. Sound-wave propagation and induced flows result from full coupling between the oscillating current, the energy balance, the ideal-gas law, and the conservation of mass and momentum on two separate timescales. Experimental verifications of the instantaneous and time-averaged effects are included.