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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.

• Influence of the orifice plate area contraction ratio on the two-phase pressure drop. • Uses 27 databases of two-phase multipliers to develop the proposed model and 5 databases to test. • Introduce an attractor to improve the two-phase multiplier prediction and the accuracy of the fits. • The procedure for orifice plate is the same for nozzles, venturi tubes, flow control valves, and similies. • The proposed model prediction presents good agreement with experimental data. The flow of a gas-liquid across the orifice plate occurs a pressure drop. It employs a two-phase multiplier to estimate the average pressure drop. In the present times, the two-phase multiplier does not account for the orifice size, becoming incomplete models. The introduction of the area contraction ratio is the novelty of this paper. The proposed model employs a two-phase multiplier depending on the quality, densities ratio, area contraction ratio, and two constants extracted from experimental databases. The proposed model has a low bias, applicable for densities ratio, (ρ L /ρ G), of 3.05 to 800 and an area contraction ratio of 0.072 to 1.000. Demonstration experimental of the dependence of the area contraction ratio. The two graphics below have the same coordinates: two-phase multiplier versus quality. The graphics use air-water databases with (rL/rG) of 773. Figure (a) shows each line corresponds to an area contraction ratio, σ. The use of log scale is necessary, otherwise the symbols will be squeeze near 0.0001 to 0.01. The x axis span of 0.0001 to 0.2 and 1 to 100 and y axis span of 1 to 100. Figure (b) shows for area contraction ratio of: 1.00, 0.75, 0.50 and 0.25 using Eq. (24). The x axis span of 0 to 1 and y axis varies from 1 to 800. The area contraction ratio spans of 0 < s £ 1. For constant x, then the higher is the fL2 so does the area contraction ratio. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]