Flow and Heat Transfer Characteristics of Impinging Bubbly Jet

Abstract

The effect of adding air into water jet flow for heat transfer enhancement was investigated for submerged impinging jet. The Reynolds number of water jet was fixed at ReL = 2.4x104, the nozzle to impingement surface distance was also fixed at L = 2D, and the volumetric fraction was varied from ???? = 0.0 to 0.7. The heat transfer measurement was studied using an infrared thermal imaging camera. The flow behavior of bubbly jet was observed by a high-speed camera. The result showed that the heat transfer of the bubbly jet for all cases were higher than the water jet case. The average Nusselt number on surface was continuously increased for increasing volumetric fraction ???? = 0.0 to 0.2. It was found that the volumetric fraction at ???? = 0.2 gave the maximum heat transfer enhancement about 33% compared to case of water jet. But the increase of volumetric fraction in range ???? = 0.2 to 0.7 decreased the average Nusselt number.