Three dimensional transient analysis of bubble dynamics in centrifugal bubble singlet oxygen generator for scalable COIL

Abstract

Chemical Oxygen Iodine Laser (COIL) is the shortest wavelength (1.315 μm) chemical laser employing singlet oxygen molecules as the pumping species and iodine atoms as lasing species. Singlet Oxygen Generator (SOG) is essentially the heart of this laser device which is basically a gas–liquid phase chemical reactor. SOG facilitates the reaction between a basic hydrogen peroxide solution (BHP, H2O2 + KOH) and chlorine gas to produce singlet oxygen molecules. Centrifugal Bubble Single Oxygen Generator (CBSOG) is a potential candidate for an alternative SOG with better operating conditions for high throughput and high power COIL systems. In CBSOG Chlorine gas is bubbled through a layer of BHP solution and the required reaction takes place at the gas–liquid interface of the formed bubbles under high speed rotation of the chamber for gravity independent operation. The performance of this device largely depends on the bubble formation characteristics and their traverse inside the BHP layer. The aim of this paper is to present the numerical analysis of the mechanics of bubble formation, detachment and movement in the BHP layer for different operating parameters as applicable to COIL. The determination of conditions for the transition from bubbling to the jetting regime at different centrifugal accelerations of high magnitude (G ∼ 204 g, 306 g & 387 g) with low liquid column thickness (∼6–8 mm) operating under low pressure (∼100 torr) is another point of focus. The Volume of Fluid (VOF) method has been used for the 3-D transient interface tracking between the phases. This paper also compares the simulation results for various gas flow rates and centrifugal accelerations with select experimental results reported elsewhere showing reasonably good agreement.