Effervescent atomization

Effervescent atomization is a method of twin-fluid atomization that involve s bubbling a small amount of gas into the liquid before it is ejected from the atomizer. The technique of bubbling gas directly into the Liquid stream inside the atomizer body is essentially different from other methods of tw in-fluid atomization (either internal or external mixing) and leads to sign ificant improvements in performance in terms of smaller drop sizes and/or l ower injection pressures. Furthermore, the amount of atomizing gas required is considerably less than what is employed in all other twin-fluid atomiza tion techniques. Effervescent atomization has been used successfully in a number of applicat ions since its inception over ten years ago. It has been well studied durin g this period, and the published literature includes experimental and analy tical investigations of both atomizer performance and the fundamental mecha nisms involved in the atomization process. The literature also includes app lication-oriented studies that report the development of effervescent atomi zers for gas turbine combustors, consumer products, furnaces and boilers, i nternal combustion (IC) engines, and incinerators. Through these studies a fair appreciation of the capabilities of the technique has been achieved. C ontinuing work is aimed at exploring the use of effervescent atomization in new areas, as well as acquiring a better understanding of current applicat ions. More in-depth studies are also in progress on the various basic mecha nisms that contribute to the overall atomization process. The purpose of this article is threefold. First, to summarize the results o btained from investigations of effervescent atomizer performance embracing wide variations in atomizer design, liquid properties, and operating condit ions. Second, to review current theories on the basic mechanisms involved i n the atomization process and to discuss the scope for future research. Thi rd, to provide an overview of current applications and to suggest possible areas for future practical applications, including fire suppression, paint sprays, agricultural sprays, and fuel injection for liquid-rockets and spar k-ignition IC engines. (C) 2001 Published by Elsevier Science Ltd.