Water Science and Engineering 2010, 3(2) 190-199 DOI:   10.3882/j.issn.1674-2370.2010.02.007  ISSN: 1674-2370 CN: 32-1785/TV

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Keywords
orifice energy dissipator
theoretical analysis
numerical simulation
two-equation turbulent model
hydraulic characteristics
Authors
HE Ning
DIAO Zhen-Xin
PubMed
Article by He,n
Article by Diao,Z.X

Theoretical and numerical study of hydraulic characteristics of orifice energy dissipator

NingHE*1, Zhen-xing ZHAO2

1. Institute of High Energy Physics, CAS, Beijing 100049, P. R. China 
2. College of Mechanics and Materials, Hohai University, Nanjing 210098, P. R. China

Abstract

Different factors affecting the efficiency of the orifice energy dissipator were investigated based on a series of theoretical analyses and numerical simulations. The main factors investigated by dimension analysis were identified, including the Reynolds number (Re), the ratio of the orifice diameter to the inner diameter of the pipe ( ), and the ratio of distances between orifices to the inner diameter of the pipe ( ). Then, numerical simulations were conducted with a two-equation turbulence model. The calculation results show the following: Hydraulic characteristics change dramatically as flow passes through the orifice, with abruptly increasing velocity and turbulent energy, and decreasing pressure. The turbulent energy appears to be low in the middle and high near the pipe wall. For the energy dissipation setup with only one orifice, when Re is smaller than 105, the orifice energy dissipation coefficient K increases rapidly with the increase of Re. When Re is larger than 105, K gradually stabilizes. As increases, K and the length of the recirculation region L1 show similar variation patterns, which inversely vary with . The function curves can be approximated as straight lines. For the energy dissipation model with two orifices, because of different incoming flows at different orifices, the energy dissipation coefficient of the second orifice (K2) is smaller than that of the first. If is less than 5, the K value of the model, depending on the variation of K2, increases with the spacing between two orifices L , and an orifice cannot fulfill its energy dissipation function. If is greater than 5, K2 tends to be steady; thus, the K value of the model gradually stabilizes. Then, the flow fully develops, and L has almost no impact on the value of K.

Keywords orifice energy dissipator   theoretical analysis   numerical simulation   two-equation turbulent model   hydraulic characteristics  
Received 2010-06-25 Revised  Online: 2010-06-25 
DOI: 10.3882/j.issn.1674-2370.2010.02.007
Fund:
Corresponding Authors: Ning HE
Email: hening@ihep.ac.cn
About author:

References:

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