The Incipient Cavitation Number of Square-Edged Orifice Plate

2014 ◽  
Vol 568-570 ◽  
pp. 1702-1705
Author(s):  
Wei Jun Wang
Keyword(s):  
Reynolds Number ◽  
Plate Thickness ◽  
Cavitation Number ◽  
Orifice Plate ◽  
Simulation Methods ◽  
Contraction Ratio ◽  
Theoretical Considerations

In the present paper, the incipient cavitations number was analyzed by theoretical considerations. By using simulation methods, it could be regarded that the incipient cavitations number was mainly dominated by the contraction ratio of the orifice plate. The less the contraction ratio of the orifice plate is, the larger is the incipient cavitations number. The effects of orifice plate’ thickness on the incipient cavitations number was not obviously and could be neglected. When Reynolds number is more than 105, Reynolds number has little impact on the incipient cavitations number.

scholarly journals Correction and laboratory investigation for energy loss coefficient of square-edged orifice plate

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110185
Author(s):  
Ai Wanzheng ◽  
Zhu Pengfei
Keyword(s):  
Energy Loss ◽  
Model Experiment ◽  
Plate Thickness ◽  
Primary Objective ◽  
Loss Coefficient ◽  
Orifice Plate ◽  
Discharge Tunnel ◽  
Energy Dissipater ◽  
Contraction Ratio ◽  
Relative Errors

A lot of studies have shown that the hydraulic characteristics of orifice plate are mainly controlled by its contraction ratio, but the thickness of square-edged orifice plate also has many impacts on energy loss characteristics. The primary objective of this study was to investigated the effects of square-edged orifice plate thickness on energy loss characteristics. In this paper, the effects of square-edged orifice plate thickness on energy loss characteristics are investigated by numerical simulation using CFD. Orifice plate discharge tunnel is axial symmetric, two dimensional numerical simulations of orifice plate discharge tunnel flow was used. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed. The results of the present research demonstrate that energy loss coefficient decreases with increase of the orifice plate thickness. The results of model experiment are consistence with the results calculated by using rectified equation in present paper. The CFD simulations and Model experiment for the flow through an orifice plate are carried out. For square-edged orifice plate energy dissipater, the relative orifice plate thickness T/D has remarkable impacts on its energy loss coefficient ξ. The Traditional equation (8) is corrected by numerical results. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed and this equation is available in the condition of d/D = 0.4–0.8, T/D = 0.05–0.25, and Re > 105(Re is Reynolds number). Comparing with the physical model experimental data, the relative errors of equation (9) is smaller than 15%.

Numerical Simulation of Characteristics of Sudden Reduction Tube Flow Based on FLUENT

2011 ◽  
Vol 255-260 ◽  
pp. 3461-3465
Author(s):  
Wan Zheng Ai ◽  
Bai Gang Huang
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Loss Coefficient ◽  
Experiment Data ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Flow Through ◽  
Spillway Tunnel ◽  
Theoretical Considerations ◽  
Sudden Reduction

Sudden reduction tube was always used in spillway tunnel, drainage pipes and so on. The energy loss coefficient of sudden reduction tube flows is an important index of sudden reduction tube. In the present paper, this coefficient and relative parameters, such as the contraction ratio and Reynolds number of the flow through sudden reduction tube, were analyzed by theoretical considerations, and their relationships were obtained by the numerical simulations. It could be concluded that the energy loss coefficient was mainly dominated by the contraction ratio. The less the contraction ratio is, the larger is the energy loss coefficient. When Reynolds number is more than 105, Reynolds number has little impact on it. An empirical expression, which was verified by comparison with other experiment data, was presented to calculate the energy loss coefficient of sudden reduction tube flows.

scholarly journals Research on the Flow Characteristics of Sudden-Reduction Oil Tube

2015 ◽  
Vol 9 (1) ◽  
pp. 77-79 ◽  
Author(s):  
Zhibin Zhang ◽  
Chunxi Lin ◽  
Weiqiang Ye ◽  
An Wei ◽  
Leming Xiao ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Region Length ◽  
Sudden Reduction

The backflow region length in sudden-reduction oil tube is not only closely associated with its energy loss, but is also closely related to the partition between orifice plate and plug. In this paper, the characteristics of backflow region length in sudden-reduction oil tube are researched. The results illustrated that backflow region length decreases with the increase in the contraction ratio. Moreover, when Reynolds number is more than 105, Reynolds number has little impact on backflow region length. Empirical expression about backflow region length in sudden-reduction oil tube is also discussed in this paper.

INCOMPRESSIBLE FLOW AT LOW REYNOLDS NUMBER IN A CONICAL ENTRANCE ORIFICE PLATE

2019 ◽  
Author(s):  
MARA NILZA ESTANISLAU REIS ◽  
Wender Oliveira ◽  
Pedro Américo Almeida Magalhães Júnior
Keyword(s):  
Reynolds Number ◽  
Incompressible Flow ◽  
Low Reynolds Number ◽  
Orifice Plate ◽  
Low Reynolds

Difference in Critical Reynolds Number Between Hagen-Poiseuille and Plane Poiseuille Flows

2001 ◽  
Author(s):  
Hidesada Kanda
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Poiseuille Flow ◽  
Average Velocity ◽  
Critical Reynolds Number ◽  
Inlet Section ◽  
Parallel Plates ◽  
Plane Poiseuille Flow ◽  
Contraction Ratio ◽  
Significant Difference

Abstract For plane Poiseuille flow, results of previous investigations were studied, focusing on experimental data on the critical Reynolds number, the entrance length, and the transition length. Consequently, concerning the natural transition, it was confirmed from the experimental data that (i) the transition occurs in the entrance region, (ii) the critical Reynolds number increases as the contraction ratio in the inlet section increases, and (iii) the minimum critical Reynolds number is obtained when the contraction ratio is the smallest or one, and there is no-shaped entrance or straight parallel plates. Its value exists in the neighborhood of 1300, based on the channel height and the average velocity. Although, for Hagen-Poiseuille flow, the minimum critical Reynolds number is approximately 2000, based on the pipe diameter and the average velocity, there seems to be no significant difference in the transition from laminar to turbulent flow between Hagen-Poiseuille flow and plane Poiseuille flow.

Reynolds number dependence of an orifice plate

2013 ◽  
Vol 30 ◽  
pp. 123-132 ◽  
Author(s):  
Oliver Büker ◽  
Peter Lau ◽  
Karsten Tawackolian
Keyword(s):  
Reynolds Number ◽  
Orifice Plate ◽  
Reynolds Number Dependence

Experimental Study of Aerodynamic Behavior Downstream of Three Flow Conditioners

2002 ◽  
Author(s):  
Boualem Laribi ◽  
Pierre Wauters ◽  
Mohamed Aichouni
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Comparative Study ◽  
Pipe Flow ◽  
Discharge Coefficient ◽  
Tube Bundle ◽  
Turbulent Pipe Flow ◽  
Orifice Plate ◽  
Flow Meter ◽  
Discharge Coefficients

The present work is concerned a comparative study of the decay of swirling turbulent pipe flow downstream of three flow conditioners, the Etoile, the Tube bundle, and the Laws perforate plate, and its effect on accuracy of orifice plate flow meter. The swirl was generated by a double 90° degrees elbows in perpendicular planes. The discharge coefficients were measured with 3 different orifice meters with β = 0.5, 0.62, 0.70 at different Reynolds number. As a conclusion, the experimental study of the three flow conditioners used separately shows that the flow need longer distance for close to fully developed pipe flow and some errors, by reason of the swirl, on the discharge coefficient were inevitable for distance less 12D.

scholarly journals The transition from sheet to cloud cavitation

2017 ◽  
Vol 817 ◽  
pp. 439-454 ◽  
Author(s):  
P. F. Pelz ◽  
T. Keil ◽  
T. F. Groß
Keyword(s):  
Reynolds Number ◽  
Cavitation Number ◽  
Wall Friction ◽  
Bubble Collapse ◽  
Penetration Length ◽  
Cloud Cavitation ◽  
Viscous Film ◽  
History Of ◽  
Good Agreement

Recent studies indicate that the transition from sheet to cloud cavitation depends on both cavitation number and Reynolds number. In the present paper this transition is investigated analytically and a physical model is introduced. In order to include the entire process, the model consists of two parts, a model for the growth of the sheet cavity and a viscous film flow model for the so-called re-entrant jet. The models allow the calculation of the length of the sheet cavity for given nucleation rates and initial nuclei radii and the spreading history of the viscous film. By definition, the transition occurs when the re-entrant jet reaches the point of origin of the sheet cavity, implying that the cavity length and the penetration length of the re-entrant jet are equal. Following this criterion, a stability map is derived showing that the transition depends on a critical Reynolds number which is a function of cavitation number and relative surface roughness. A good agreement was found between the model-based calculations and the experimental measurements. In conclusion, the presented research shows the evidence of nucleation and bubble collapse for the growth of the sheet cavity and underlines the role of wall friction for the evolution of the re-entrant jet.

FLOW FORMS IN A CHANNEL OF SMALL EXPONENTIAL DIVERGENCE

1934 ◽  
Vol 11 (6) ◽  
pp. 770-779 ◽  
Author(s):  
G. N. Patterson
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Velocity Distribution ◽  
Initial Velocity ◽  
Reynolds Numbers ◽  
Transitional Region ◽  
Empirical Equations ◽  
Initial Velocity Distribution ◽  
General Flow ◽  
Theoretical Considerations

The motion of air through a channel of small exponential divergence has been investigated experimentally. A flow form derived by Blasius from theoretical considerations has been shown to exist in the range [Formula: see text] for the Reynolds number. The dependence of the general flow form on the initial velocity distribution where the divergence begins has been studied. It has been found that when this initial velocity distribution is parabolic, indicating a laminar motion in the throat of the channel, the flow form is symmetrical. Further investigations have shown that when the initial velocity distribution indicates that the motion near the walls in the throat of the channel lies in the transitional region between a laminar and a turbulent flow, then the flow form is unsymmetrical. Empirical equations have been obtained which give (1) the initial velocity distribution in the transitional region at R = 75.1, and (2) the motion near the walls where the divergence begins for Reynolds numbers lying in the range [Formula: see text].

Three-Dimensional Vortex Structure in a Leading-Edge Separation Bubble at Moderate Reynolds Numbers

1991 ◽  
Vol 113 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Kyuro Sasaki ◽  
Masaru Kiya
Keyword(s):  
Reynolds Number ◽  
Separation Bubble ◽  
Plate Thickness ◽  
Three Dimensional ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Vortex Filaments ◽  
Separated Shear Layer ◽  
Hydrogen Bubbles ◽  
Edge Separation

This paper describes the results of a flow visualization study which concerns three-dimensional vortex structures in a leading-edge separation bubble formed along the sides of a blunt flat plate. Dye and hydrogen bubbles were used as tracers. Reynolds number (Re), based on the plate thickness, was varied from 80 to 800. For 80 < Re < 320, the separated shear layer remains laminar up to the reattachment line without significant spanwise distortion of vortex filaments. For 320 < Re < 380, a Λ-shaped deformation of vortex filaments appears shortly downstream of the reattachment and is arranged in-phase in the downstream direction. For Re > 380, hairpin-like structures are formed and arranged in a staggered manner. The longitudinal and spanwise distances of the vortex arrangement are presented as functions of the Reynolds number.

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