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Mathematical Problems in Engineering
Volume 2014, Article ID 259593, 7 pages
http://dx.doi.org/10.1155/2014/259593
Research Article

Numerical Investigation of a Liquid-Gas Ejector Used for Shipping Ballast Water Treatment

1School of Electrical and Electronic Engineering, Merz Court, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
2Department of Mechanical Engineering, Dong-A University, Busan 604-714, Republic of Korea
3Department of Engineering Mechanics, Hohai University, Nanjing 210098, China
4NK Co., Ltd., Shinpyeong-dong, Saha-gu, Busan 604-030, Republic of Korea

Received 31 October 2013; Revised 24 February 2014; Accepted 19 March 2014; Published 4 June 2014

Academic Editor: Yonghong Wu

Copyright © 2014 Xueguan Song et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Shipping ballast water can have significant ecological and economic impacts on aquatic ecosystems. Currently, water ejectors are widely used in marine applications for ballast water treatment owing to their high suction capability and reliability. In this communication, an improved ballast treatment system employing a liquid-gas ejector is introduced to clear the ballast water to reduce environmental risks. Commonly, the liquid-gas ejector uses ballast water as the primary fluid and chemical ozone as the secondary fluid. In this study, high-pressure water and air, instead of ballast water and ozone, are considered through extensive numerical and experimental research. The ejector is particularly studied by a steady three-dimensional multiphase computational fluid dynamics (CFD) analysis with commercial software ANSYS-CFX 14.5. Different turbulence models (including standard , RNG , SST, and ) with different grid size and bubble size are compared extensively and the experiments are carried out to validate the numerical design and optimization. This study concludes that the RNG turbulence model is the most efficient and effective for the ballast water treatment system under consideration and simple change of nozzle shape can greatly improve the ejector performance under high back pressure conditions.