Abstract

High-intensity discharge (HID) lamps are one type of arc discharge lamp. They are routinely used to illuminate stadiums, warehouses, roadways, greenhouses and other venues requiring a large amount of light from a compact source. Although HID lamps are comparably efficient—roughly 25% of the electrical energy delivered to these lamps is converted to useful light—further increases in efficiency are limited by buoyancy-driven flows of the hot gas comprising the arc. Researchers have shown that these undesirable flows can be effectively countered by acoustic streaming flows: time-mean flows induced by time-periodic standing acoustic waves, the latter being excited by modulating the lamp current at an acoustic eigenfrequency. Interestingly, neither the very large magnitude nor the orientation of acoustic streaming flows arising in HID lamps can be explained by classical streaming theories. In this talk, a new theory will be described that properly accounts for both these features. A computationally-efficient strategy for modeling the thermo-fluid mechanics of acoustically-stabilized HID lamps will also be discussed.