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.

scholarly journals Research on Backflow Region Length of Sudden-Enlarge Oil Tube Flows

2014 ◽  
Vol 8 (1) ◽  
pp. 974-976
Author(s):  
Jiahong Wang ◽  
Wanzheng Ai
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Region Length

Sudden-enlarge tube has important applications in reality lives. The backflow region length in sudden-enlarge tube flows is closely related with its energy loss. In this paper, the characteristics of backflow region length in suddenenlarge oil tube flows are researched. The results show that backflow region length decreases with the increase of the contraction ratio; when Reynolds number is more than 105, Reynolds number have little impacts on backflow region length. Empirical expression about backflow region length is also obtained by fitting curve in this paper.

On the theory of unsteady high Reynolds number flow through a circular aperture

1979 ◽  
Vol 366 (1725) ◽  
pp. 205-223 ◽  
Keyword(s):  
Reynolds Number ◽  
Strouhal Number ◽  
High Reynolds Number ◽  
Circular Aperture ◽  
Mean Flow ◽  
Reynolds Number Flow ◽  
Contraction Ratio ◽  
Number Flow ◽  
Flow Through ◽  
High Reynolds

This paper examines the theory of the unsteady motion caused by fluctuations in the driving pressure of a high Reynolds number mean flow through a circular aperture in a thin rigid plate. A theoretical model is proposed which is amenable to exact analytical treatment, and involves the shedding of vorticity from the rim of the aperture. The theory determines the dependence of the Rayleigh conductivity of the aperture on the Strouhal number, and provides quantitative estimates for the rate of dissipation of large scale ordered structures as a result of the generation of turbulence at the apertures in a perforated liner. The limit of zero Strouhal number yields a description of steady high Reynolds number flow, the contraction ratio of the emerging jet being predicted to be equal to the minimum theoretical value of ½. Application is made to the problem of sound trans­mission through a uniformly perforated screen in the presence of a low Mach number bias flow.

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%.

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 Numerical Analysis of Energy Loss Coefficient in Pipe Contraction Using ANSYS CFX Software

2017 ◽  
Vol 3 (4) ◽  
pp. 288-300 ◽  
Author(s):  
Kourosh Nosrati ◽  
Ahmad Tahershamsi ◽  
Seyed Heja Seyed Taheri
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Numerical Analysis ◽  
Energy Loss ◽  
Euler Number ◽  
Stokes Equations ◽  
Linear Increase ◽  
Loss Coefficient ◽  
Relative Roughness ◽  
Ansys Cfx

The purpose of this study is the numerical analysis of energy loss coefficient in pipe contraction using ANSYS CFX software. To this end, the effect of the dimensionless parameters of Euler number, Reynolds number, and relative roughness on energy loss coefficient has been investigated and eventually an overall formula to determine the energy loss coefficient in these transitions has been provided. In order to solve the fluid turbulence equations in the pipe, standard K-Epsilon model has been used. For this purpose, first the geometry of pipe transitions was designed in 3-D, using Solid Works software, and then the transitions were meshed by ANSYS MESHING. The initial simulation of transitions including boundary conditions of outlet, inlet and wall, was carried out by a pre-processor called CFX-PRE. Furthermore, to solve the equations governing the fluid flow in the pipes (Navier-Stokes equations) the CFX-SOLVER was used. And finally, the results were extracted using a post-processor called CFD-POST.The results indicated that the energy loss coefficient, contrary to the findings of previous researchers, is not only related to transition geometry, but also is dependent on the Reynolds number, relative roughness of the wall and Euler number. By increasing the Reynolds Number and turbulence of fluid flow in transitions, the energy loss coefficient is reduced. Moreover, by increasing the relative roughness in the transition’s wall the energy loss coefficient is reduced. The increase in pressure fluctuation causes the increase of Euler number which leads to the linear increase of energy loss coefficient.

Minor Losses Due to Flow Through a Rounded Sudden Expansion

2003 ◽  
Author(s):  
Barton L. Smith
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
Steady Flow ◽  
Loss Coefficient ◽  
Pressure Recovery ◽  
Sudden Expansion ◽  
Flow Energy ◽  
Uniform Velocity ◽  
Flow Through ◽  
Minor Losses

Experiments on steady flow through a nominally 2-D exit geometry with rounded edges are presented. The minor loss coefficient, K, can be greater than unity for sudden expansions with non-uniform velocity profiles. Pressure recovery due to deceleration of the exiting flow before it detaches results in conversion of kinetic energy to flow energy and a reduced the value of K. It is shown that K is a function of the dimensionless edge radius and the Reynolds number. Substantial pressure recovery is reported at large Re for r/h < 1.

Bifurcations of Flow Through Plane Symmetric Channel Contraction

2002 ◽  
Vol 124 (2) ◽  
pp. 444-451 ◽  
Author(s):  
T. P. Chiang ◽  
Tony W. H. Sheu
Keyword(s):  
Reynolds Number ◽  
Critical Reynolds Number ◽  
Reynolds Numbers ◽  
Incompressible Fluid Flow ◽  
Channel Geometry ◽  
Plane Symmetric ◽  
Symmetric Channel ◽  
Contraction Ratio ◽  
Critical Reynolds Numbers ◽  
Flow Through

Computational investigations have been performed into the behavior of an incompressible fluid flow in the vicinity of a plane symmetric channel contraction. Our aim is to determine the critical Reynolds number, above which the flow becomes asymmetric with respect to the channel geometry using the bifurcation diagram. Three channels, which are characterized by the contraction ratio, are studied and the critical Reynolds numbers are determined as 3075, 1355, and 1100 for channels with contraction ratios of 2, 4, and 8, respectively. The cause and mechanism explaining the transition from symmetric to asymmetric states in the symmetric contraction channel are also provided.

Use Deflected Trailing Edge to Improve the Aerodynamic Performance and Develop Low Solidity LPT Cascade

2017 ◽  
Vol 34 (3) ◽  
Author(s):  
Li Chao ◽  
Yan Peigang ◽  
Wang Xiangfeng ◽  
Han Wanjin ◽  
Wang Qingchao
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Flow Control ◽  
Control Mechanism ◽  
Low Pressure ◽  
Aerodynamic Performance ◽  
Loss Coefficient ◽  
Freestream Turbulence ◽  
Trailing Edge ◽  
Low Pressure Turbine

AbstractThis paper investigates the feasibility of improving the aerodynamic performance of low pressure turbine (LPT) blade cascades and developing low solidity LPT blade cascades through deflected trailing edge. A deflected trailing edge improved aerodynamic performance of both LPT blade cascades and low solidity LPT blade cascades. For standard solidity LPT cascades, deflecting the trailing edge can decrease the energy loss coefficient by 20.61 % for a Reynolds number (Re) of 25,000 and freestream turbulence intensities (FSTI) of 1 %. For a low solidity LPT cascade, aerodynamic performance was also improved by deflecting the trailing edge. Solidity of the LPT cascade can be reduced by 12.5 % for blades with a deflected trailing edge without a drop in efficiency. Here, the flow control mechanism surrounding a deflected trailing edge was also revealed.

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