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Effect of the Area Contraction Ratio on the Hydraulic Characteristics of the Toothed Internal Energy Dissipaters

1
College of Water Resources and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
2
Water conservancy engineering design Ltd. of Shanxi Qian Cheng, Taiyuan 030024, China
*
Author to whom correspondence should be addressed.
Water 2019, 11(7), 1406; https://doi.org/10.3390/w11071406
Received: 16 May 2019 / Revised: 30 June 2019 / Accepted: 3 July 2019 / Published: 9 July 2019
(This article belongs to the Special Issue Environmental Hydraulics Research)
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Abstract

Toothed internal energy dissipaters (TIED) are a new type of internal energy dissipaters, which combines the internal energy dissipaters of sudden reduction and sudden enlargement forms with the open-flow energy dissipation together. In order to provide a design basis for an optimized body type of the TIED, the effect of the area contraction ratio (ε) on the hydraulic characteristics, including over-current capability, energy dissipation rate, time-averaged pressure, pulsating pressure, time-averaged velocity, and pulsating velocity, were studied using the methods of a physical model test and theoretical analysis. The main results are as follows. The over-current capability mainly depends on ε, and the larger ε is, the larger the flow coefficient is. The energy dissipation rate is proportional to the quadratic of Re and inversely proportional to ε. The changes of the time-averaged pressure coefficients under each flow are similar along the test pipe, and the differences of the time-averaged pressure coefficient between the inlet of the TIED and the outlet of the TIED decrease with the increase of ε. The peaks of the pulsating pressure coefficient appear at 1.3 D after the TIED and are inversely proportional to ε. When the flow is 18 l/s and ε increases from 0.375 to 0.625, the maximum of time-averaged velocity coefficient on the line of Z/D = 0.42 reduces from 2.53 to 1.17, and that on the line of Z/D = 0 decreases from 2.99 to 1.74. The maximum values of pulsating velocity on the line of Z/D = 0.42 appear at 1.57D and those of Z/D = 0 appear at 2.72D, when the flow is 18 l/s. The maximum values of pulsating velocity decrease with the increase of ε. Finally, two empirical expressions, related to the flow coefficient and energy loss coefficient, are separately presented. View Full-Text
Keywords: toothed internal energy dissipaters (TIED); area contraction ratio; over-current capability; energy dissipation rate; time-averaged pressure; pulsating pressure; time-averaged velocity; pulsating velocity toothed internal energy dissipaters (TIED); area contraction ratio; over-current capability; energy dissipation rate; time-averaged pressure; pulsating pressure; time-averaged velocity; pulsating velocity
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Zhang, T.; Hao, R.-X.; Zheng, X.-Q.; Zhang, Z. Effect of the Area Contraction Ratio on the Hydraulic Characteristics of the Toothed Internal Energy Dissipaters. Water 2019, 11, 1406.

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