Oxygen transfer characteristics of bubbly jet in regular waves
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Available online at https://link.springer.com/journal/42241 http://www.jhydrodynamics.com Journal of Hydrodynamics, 2020, 32(5): 879-887 https://doi.org/10.1007/s42241-020-0061-x
Oxygen transfer characteristics of bubbly jet in regular waves * Ze-gao Yin , De-chun Liu, Yuan Li, Yan-xu Wang College of Engineering, Ocean University of China, Qingdao 266100, China (Received February 15, 2019, Revised July 23, 2019, Accepted August 29, 2019, Published online October 29, 2020) ©China Ship Scientific Research Center 2020 Abstract: The dissolved oxygen level is an important index of the water environment, and in this paper, the oxygen transfer of the bubbly jet in regular waves is investigated numerically and experimentally. The Reynolds-averaged Navier-Stokes equations, the re-normalisation group k - equations, and the volume of fluid (VOF) technique are used along with a 2-D CFD model to simulate the wave and bubble motions as well as the turbulence, and a dissolved oxygen transport equation is used to model the oxygen transfer behavior both through the bubbly interface and the wave surface. A series of experiments are conducted to validate the mathematical model, with good agreement. In addition, a group of dimensionless parameters are defined from the wave parameter and the aeration parameter, and their relationships with the total oxygen transfer coefficient are explored. Furthermore, the dimensional analysis and the least squares methods are used to derive simple prediction formulas for the total oxygen transfer coefficient, and they are validated with the related experimental data. Key words: Bubbly jet, regular wave, mathematical model, total oxygen transfer coefficient
Introduction The dissolved oxygen (DO) plays an important role in the survival and the reproduction of fishes and other species in water, and it is closely related to the environment and the ecology of the oceans. In recent years, the sea hypoxia aggravates due to the water eutrophication and the climate warming tendency[1-2]. Artificial aeration is widely used to increase the oxygen in water of lakes, reservoirs and wastewater treatment systems[3-4]. Tojo and Miyanami[5] and Mueller et al.[6] investigated the oxygen transfer characteristics in the gas-liquid jet tank experimentally. Baylar and Emiroglu[7] studied the entrainment rate and the oxygen transfer efficiency of the air bubbles through circular nozzles. Surinder[8] experimentally examined the oxygen transfer efficiency of multiple inclined plunging jets in a water pool. Bagatur and Onen[9] presented new formulations to explore the flow characteristics in the plunging water jet system. Jahromi and Khiadani[10] proposed two equations to estimate the oxygen transfer * Project supported by the National Natural Science Foundation of China (Grant Nos. 51879251, 51579229), the Key Research and Development Plan of Shandong Province, China (Grant No. 2017GHY15103) . Biography: Ze-gao Yin (1977-), Male, Ph. D., Professor Corresponding author: Ze-gao Yin, E-mail: [email protected]
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