A Series Pressure Drop Representation for Flow Through Orifice Tubes

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
T. A. Jankowski ◽  
E. N. Schmierer ◽  
F. C. Prenger ◽  
S. P. Ashworth
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Simple Model ◽  
Pressure Drop ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
In Series ◽  
Orifice Flow ◽  
Flow Through ◽  
Length To Diameter Ratio

A simple model is developed here to predict the pressure drop and discharge coefficient for incompressible flow through orifices with length-to-diameter ratio greater than zero (orifice tubes) over wide ranges of Reynolds number. The pressure drop for flow through orifice tubes is represented as two pressure drops in series; namely, a pressure drop for flow through a sharp-edged orifice in series with a pressure drop for developing flow in a straight length of tube. Both of these pressure drop terms are represented in the model using generally accepted correlations and experimental data for developing flows and sharp-edged orifice flow. We show agreement between this simple model and our numerical analysis of laminar orifice flow with length-to-diameter ratio up to 15 and for Reynolds number up to 150. Agreement is also shown between the series pressure drop representation and experimental data over wider ranges of Reynolds number. Not only is the present work useful as a design correlation for equipment relying on flow through orifice tubes but it helps to explain some of the difficulties that previous authors have encountered when comparing experimental observation and available theories.

Measurement of Pressure Drop in a Liquid Metal Reactor Fuel Assembly

2002 ◽  
Author(s):  
Seok Ki Choi ◽  
Il Kon Choi ◽  
Kil Yong Lee ◽  
Ho Yun Nam ◽  
Jong Hyeun Choi ◽  
...  
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Fuel Assembly ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
Liquid Metal Reactor ◽  
The Wire ◽  
Measured Pressure ◽  
Reactor Fuel Assembly

An experimental study has been carried out to measure the pressure drop in a 271-pin fuel assembly of a liquid metal reactor. The rod pitch to rod diameter ratio (P/D) of the fuel assembly is 1.2 and the wire lead length to rod diameter ratio (H/D) is 24.84. Measurements are made for five different sections in a fuel assembly; inlet orifice, fuel assembly inlet, wire-wrapped fuel assembly, fuel assembly outlet and fuel assembly upper region. A series of water experiments have been conducted changing flow rate and water temperature. It is shown that the pressure drops in the inlet orifice and in the wire-wrapped fuel assembly are much larger than those in other regions. The measured pressure drop data in a wire-wrapped fuel assembly region is compared with the existing four correlations. It is shown that the correlation proposed by Cheng and Todreas fits the best with the present experimental data among the four correlations considered.

Measurement of Pressure Drop in a Full-Scale Fuel Assembly of a Liquid Metal Reactor

2003 ◽  
Vol 125 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Seok Ki Choi ◽  
Il Kon Choi ◽  
Ho Yun Nam ◽  
Jong Hyeun Choi ◽  
Hoon Ki Choi
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Fuel Assembly ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
Liquid Metal Reactor ◽  
The Wire ◽  
Measured Pressure

An experimental study has been carried out to measure the pressure drop in a 271-pin fuel assembly of a liquid metal reactor. The rod pitch to rod diameter ratio P/D of the fuel assembly is 1.2 and the wire lead length to rod diameter ratio H/D is 24.84. Measurements are made for five different sections in a fuel assembly; inlet orifice, fuel assembly inlet, wire-wrapped fuel assembly, fuel assembly outlet and fuel assembly upper region. A series of water experiments have been conducted changing flow rate and water temperature. It is shown that the pressure drops in the inlet orifice and in the wire-wrapped fuel assembly are much larger than those in other regions. The measured pressure drop data in a wire-wrapped fuel assembly region is compared with the existing four correlations. It is shown that the correlation proposed by Cheng and Todreas fits best with the present experimental data among the four correlations considered.

Comparison of Aerobic and Anoxic-Aerobic Digestion of Waste Activated Sludge

1985 ◽  
Vol 17 (8) ◽  
pp. 1475-1478 ◽  
Author(s):  
A P. C. Warner ◽  
G. A. Ekama ◽  
G v. R. Marais
Keyword(s):  
Experimental Data ◽  
Activated Sludge ◽  
Waste Activated Sludge ◽  
Activated Sludge Process ◽  
Cycle Times ◽  
Waste Sludge ◽  
Volatile Solids ◽  
In Series ◽  
Flow Through ◽  
Theoretical Simulations

The laboratory scale experimental investigation comprised a 6 day sludge age activated sludge process, the waste sludge of which was fed to a number of digesters operated as follows: single reactor flow through digesters at 4 or 6 days sludge age, under aerobic and anoxic-aerobic conditions (with 1,5 and 4 h cycle times) and 3-in-series flow through aerobic digesters each at 4 days sludge age; all digesters were fed draw-and-fill wise once per day. The general kinetic model for the aerobic activated sludge process set out by Dold et al., (1980) and extended to the anoxic-aerobic process by van Haandel et al., (1981) simulated accurately all the experimental data (Figs 1 to 4) without the need for adjusting the kinetic constants. Both theoretical simulations and experimental data indicate that (i) the rate of volatile solids destruction is not affected by the incorporation of anoxic cycles and (ii) the specific denitrification rate is independent of sludge age and is K4T = 0,046(l,029)(T-20) mgNO3-N/(mg active VSS. d) i.e. about 2/3 of that in the secondary anoxic of the single sludge activated sludge stystem. An important consequence of (i) and (ii) above is that denitrification can be integrated easily in the steady state digester model of Marais and Ekama (1976) and used for design (Warner et al., 1983).

Experimental Investigation of Pressure Drop Characteristics of Viscous Fluid Flow Through Small Diameter Orifices

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Lalit Kumar Bohra ◽  
Leo M. Mincks ◽  
Srinivas Garimella
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Viscous Fluid ◽  
Euler Number ◽  
Small Diameter ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Operating Conditions ◽  
Turbulent Regime ◽  
Pressure Drops

Abstract An experimental study on the flow of a highly viscous fluid through small diameter orifices was conducted. Pressure drops were measured for each of nine orifices, including orifices of nominal diameter 0.5, 1, and 3 mm and three different orifice thicknesses, over wide ranges of flow rates and temperatures. The fluid under consideration exhibits steep dependence of the properties (changes of several orders of magnitude) as a function of temperature and pressure and is also non-Newtonian at the lower temperatures. At small values of Reynolds number, an increase in aspect ratio (length/diameter ratio of the orifice) causes an increase in Euler number. It was also found that at extremely low Reynolds numbers, the Euler number was very strongly influenced by the Reynolds number, while the dependence becomes weaker as the Reynolds number increases toward the turbulent regime, and the Euler number tends to assume a constant value determined by the aspect ratio and the diameter ratio. A two-region (based on Reynolds number) model was developed to predict Euler number as a function of diameter ratio, aspect ratio, viscosity ratio, and generalized Reynolds number. It is shown that for such a highly viscous fluid with some non-Newtonian behavior, accounting for the shear rate through the generalized Reynolds number results in a considerable improvement in the predictive capabilities of the model. Over the laminar, transition, and turbulent regions, the model predicts 86% of the data within ±25% for the geometry and operating conditions investigated in this study.

Computational study on drilling mud flow through wellbore annulus by Giesekus viscoelastic model

2020 ◽  
pp. 095440892094380
Author(s):  
Mohammad Amir Hasani ◽  
Mahmood Norouzi ◽  
Morsal Momeni Larimi ◽  
Reza Rooki
Keyword(s):  
Reynolds Number ◽  
Friction Coefficient ◽  
Pressure Drop ◽  
Elastic Property ◽  
Taylor Number ◽  
Drilling Fluids ◽  
Drilling Mud ◽  
Axial Pressure ◽  
Flow Through ◽  
Mud Flow

Cuttings transport from wellbore annulus to the surface via drilling fluids is one of the most important problems in gas and oil industries. In the present paper, the effects of viscoelastic property of drilling fluids on flow through wellbore annulus are studied numerically by use of computational fluid dynamics simulation in OpenFOAM software. This problem is simulated as the flow between two coaxial annulus cylinders and the inner cylinder is rotating through its axes. Here, the Giesekus model is used as the nonlinear constitutive equation. This model brings the nonlinear viscosity, normal stress differences, extensional viscosity and elastic property. The numerical solution is obtained using the second order finite volume method by considering PISO algorithm for pressure correction. The effect of elasticity, Reynolds number, Taylor number and mobility factor on the velocity and stress fields, pressure drop, and important coefficient of drilling mud flow is studied in detail. The results predicted that increasing elastic property of drilling mud lead to an initial sharp drop in the axial pressure gradient as well as Darcy-Weisbach friction coefficient. Increasing the Reynolds number at constant Taylor number, resulted an enhancing in the axial pressure drop of the fluid but Darcy-Weisbach [Formula: see text] friction coefficient mainly reduced.

Lateral-Flow Effect on Endwall Heat Transfer and Pressure Drop in a Pin-Fin Trapezoidal Duct of Various Pin Shapes

2000 ◽  
Vol 123 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Jenn-Jiang Hwang ◽  
Chau-Ching Lu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Lateral Flow ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
Flow Reynolds Number ◽  
Outlet Flow ◽  
Flow Through

The effects of lateral-flow ejection 0<ε<1.0, pin shapes (square, diamond, and circular), and flow Reynolds number (6000<Re<40,000) on the endwall heat transfer and pressure drop for turbulent flow through a pin-fin trapezoidal duct are studied experimentally. A staggered pin array of five rows and five columns is inserted in the trapezoidal duct, with the same spacings between the pins in the streamwise and spanwise directions: Sx/d=Sy/d=2.5. Three different-shaped pins of length from 2.5<l/d<4.6 span the distance between two endwalls of the trapezoidal duct. Results reveal that the pin-fin trapezoidal duct with lateral-flow rate of ε=0.3-0.4 has a local minimum endwall-averaged Nusselt number and Euler number for all pin shapes investigated. The trapezoidal duct of lateral outlet flow only (ε=1.0) has the highest endwall heat transfer and pressure drop. Moreover, the square pin results in a better heat transfer enhancement than the diamond pin, and subsequently than the circular pin. Finally, taking account of the lateral-flow rate and the flow Reynolds number, the work develops correlations of the endwall-averaged heat transfer with three different pin shapes.

Study on the Minimum Drag Coefficient Phenomenon of Supercritical Pressure Water in the Pseudocritical Region

2012 ◽  
Author(s):  
Xianliang Lei ◽  
Huixiong Li ◽  
Shuiqing Yu ◽  
Yifan Zhang ◽  
Tingkuan Chen
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Drag Coefficient ◽  
Supercritical Pressure ◽  
Pressure Drops ◽  
Minimum Drag ◽  
Wide Range ◽  
Pressure Water ◽  
Isothermal Flows ◽  
Supercritical Pressure Water

With the development of supercritical (and even ultra-supercritical) pressure boilers (SCBs) with high capacities, and at the same time, with the consideration of supercritical pressure water-cooled reactors (SCWRs) as one of the six most promising reactor concepts accepted in the Generation IV International Forum (GIF), flow and heat transfer of supercritical water becomes more and more important for both the design and operation safety of the related facilities. Thermo-hydraulic characteristics are among the issues, which are of special significance for the SCBs and SCWRs. It has been found that at supercritical pressures, the hydraulic resistance of water exhibits special characteristics in regions near its pseudo-critical point, which is hereafter called the minimum drag coefficient phenomenon. Experimental investigation was carried out in the present study to investigate further the characteristics of drag coefficient of supercritical pressure water under different conditions. The total pressure drop characteristic of water flowing in smooth tube and internally ribbed tube under the supercritical pressures was measured in experiments with a wide range of operational parameters, such as the system pressures ranging from 23 to 28 MPa, the average heat fluxes varied from 100 kW/m2 to 500kW/m2, and the mass fluxes of water in a range of 600 ∼ 1050 kg/m2s. The experimental data were compared with prediction results calculated by existing common correlations for single phase pressure drops, and large discrepancies were observed between the experimental data and the prediction results. Furthermore, the pressure drops characteristics of supercritical pressure water in cases with different tube arrangement and test conditions were compared with each other, such as that in horizontal tubes and vertical tubes, and that in isothermal flows and in non-isothermal flows. Additionally, this phenomenon observed in the present studies was also analyzed by using computational fluid dynamics technology, and the mechanism of pressure drop variation was reasonably explained. It was found that the deviation appeared between the previously proposed drag coefficient correlations and the present experimental data was mainly owning to ignoring the variation of an existence of the minimum drag coefficient in the pseudo critical region in previous studies, and based on the data obtained in this study, a new correlation for drag coefficient for supercritical pressure water was presented.

Prediction of Pressure Drop for Incompressible Flow Through Screens

1993 ◽  
Vol 115 (2) ◽  
pp. 239-242 ◽  
Author(s):  
E. Brundrett
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Incompressible Flow ◽  
Pressure Loss ◽  
Effective Porosity ◽  
Local Damage ◽  
Number Range ◽  
Flow Through ◽  
Careful Specification ◽  
Cosine Law

A new pressure loss correlation predicts flow through screens for the wire Reynolds number range of 10−4 to 104 using the conventional orthogonal porosity and a function of wire Reynolds number. The correlation is extended by the conventional cosine law to include flow that is not perpendicular to the screen. The importance of careful specification of wire diameter for accurate predictions of porosity is examined. The effective porosity is influenced by the shape of the woven wires, by any local damage, and by screen tension.

Heat Exchanger Shellside Pressure Drop: Comparison of Predictions With Experimental Data

1988 ◽  
Vol 110 (1) ◽  
pp. 68-76 ◽  
Author(s):  
R. S. Kistler ◽  
J. M. Chenoweth
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Flow Induced Vibration ◽  
Ongoing Research ◽  
Pressure Drops ◽  
Complementary Method ◽  
Nozzle Pressure

A unique set of heat exchanger shellside pressure drop experimental data has become available from experiments at Argonne National Laboratory as a part of an ongoing research program in flow-induced vibration. These data provide overall pressure drop for a number of typical industrial heat exchanger configurations in addition to incremental pressure drop measurements along the shellside path. The test program systematically varied the baffle spacing, the tubefield pattern, and nozzle size for a series of isothermal water tests for segmentally baffled bundles. Also recently a comprehensive method has been published in the Heat Exchanger Design Handbook (HEDH) for the prediction of bundle shellside pressure drops. A search of the literature failed to reveal a complementary method for predicting the shellside nozzle pressure losses. This paper compares the predicted with the measured data and validates the adequacy and limitations of the HEDH method for full bundles of plain tubes. It further applies an extension to the method for no-tubes-in-the-window bundles. Adjustments were indicated to improve the predictions for finned tubes and methods were developed to predict shellside nozzle pressure drops. Overall pressure drop predictions were within plus or minus 20 percent.

scholarly journals Modeling of Laminar Flows in Rough-Wall Microchannels

2005 ◽  
Vol 128 (4) ◽  
pp. 734-741 ◽  
Author(s):  
R. Bavière ◽  
G. Gamrat ◽  
M. Favre-Marinet ◽  
S. Le Person
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Modeling ◽  
Pressure Drop ◽  
Analytical Model ◽  
Analytical Approach ◽  
Laminar Flows ◽  
Numerical Results ◽  
Rough Wall ◽  
Relative Roughness

Numerical modeling and analytical approach were used to compute laminar flows in rough-wall microchannels. Both models considered the same arrangements of rectangular prism rough elements in periodical arrays. The numerical results confirmed that the flow is independent of the Reynolds number in the range 1–200. The analytical model needs only one constant for most geometrical arrangements. It compares well with the numerical results. Moreover, both models are consistent with experimental data. They show that the rough elements drag is mainly responsible for the pressure drop across the channel in the upper part of the relative roughness range.

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