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An Experimental Study of Air Entrainment and Oxygen Transfer at a Water Jet from a Nozzle with Air Holes
Author(s) -
Baylar Ahmet,
Emiroglu M. Emin
Publication year - 2004
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143004x141780
Subject(s) - nozzle , air entrainment , aeration , entrainment (biomusicology) , mechanics , bubble , air water , jet (fluid) , oxygen , secondary air injection , environmental science , penetration (warfare) , airflow , atmospheric pressure , chemistry , materials science , thermodynamics , meteorology , physics , engineering , organic chemistry , operations research , rhythm , acoustics
An adequate supply of dissolved oxygen is important in natural rivers and in some water treatment processes. The dissolved oxygen concentration can be enhanced by entraining air bubbles in a receiving pool. When a water jet impinges a receiving pool at rest, air bubbles may be entrained and carried away below the pool free surface. This process is called plunging water jet entrainment and aeration . This paper describes an experimental study of the air entrainment rate and oxygen transfer efficiency of circular nozzles with and without air holes. In particular, the effect of varying the number, positions, and open/close status of the air holes is investigated. A negative pressure occurred depending on the air holes opened on the circular nozzles. This phenomenon affected the water jet expansion, water jet shape, air entrainment, and bubble penetration depth and, hence, the oxygen transfer efficiency. It was demonstrated that the air entrainment rate and the oxygen transfer efficiency of the circular nozzles with air holes were better than those of the circular nozzles without air holes. Therefore, adding air holes to a simple, circular nozzle could lead to a significantly increased air entrainment rate and oxygen transfer efficiency.