Efficiency Prediction of Centrifugal Pump Using the Modified Affinity Laws

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Rahul Agarwal ◽  
Abhay Patil ◽  
Gerald Morrison
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Flow Coefficient ◽  
Dimensionless Numbers ◽  
Pump Design ◽  
Wide Range ◽  
Laminar And Turbulent Flow ◽  
Data Points ◽  
Case Validation

Abstract This research is a continuation of efforts aimed at establishing the modified affinity laws for viscosity to predict the pump performance directly from a plot in terms of dimensionless numbers, i.e., flow coefficient, Reynolds number, head coefficient, and efficiency. The group has earlier proposed modified head coefficient affinity law. This work proposes and validates a similar efficiency plot that completes the set of modified affinity laws that include all the input and output parameters for a specific pump design and type. A wide range of viscosities and flow rates are considered for CFD analysis to have a comprehensive set of data that includes enough data points to comment on both the laminar and turbulent flow cases categorized based on the hydraulic Reynolds number (2300). Initial analysis shows some inconsistency based on laminar versus turbulent simulation model selection which is addressed in the latter part of this work. In general, two curves can be constructed for laminar and turbulent flow cases. These curves have different axes parameters (exponents of the dimensionless numbers) depending on the plot being for a laminar or a turbulent flow case. Validation with established experimental data shows good agreement in terms of the variation of axes parameters (their exponents) depending on the pump type for a single suction impeller and a double suction impeller pump. The distinction between laminar and turbulent flow cases is found to be applicable to established experimental data as well.

Affinity Law Modified to Predict the Pump Head Performance for Different Viscosities Using the Morrison Number

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Abhay Patil ◽  
Gerald Morrison
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Sharp Change ◽  
Fluid Viscosity ◽  
Pump Head ◽  
Laminar And Turbulent Flow ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

The goal of this study is to provide pump users a simple means to predict a pump's performance change due to changing fluid viscosity. During the initial investigation, it has been demonstrated that pump performance can be represented in terms of the head coefficient, flow coefficient, and rotational Reynolds number with the head coefficient data for all viscosities falling on the same curve when presented as a function of ф*Rew−a. Further evaluation of the pump using computational fluid dynamics (CFD) simulations for wider range of viscosities demonstrated that the value of a (Morrison number) changes as the rotational Reynolds number increases. There is a sharp change in Morrison number in the range of 104<Rew<3*104 indicating a possible flow regime change between laminar and turbulent flow. The experimental data from previously published literature were utilized to determine the variation in the Morrison number as the function of rotational Reynolds number and specific speed. The Morrison number obtained from the CFD study was utilized to predict the head performance for the pump with known design parameters and performance from published literature. The results agree well with experimental data. The method presented in this paper can be used to establish a procedure to predict any pump's performance for different viscosities; however, more data are required to completely build the Morrison number plot.

Stalling Pressure Rise Capability of Axial Flow Compressor Stages

1981 ◽  
Vol 103 (4) ◽  
pp. 645-656 ◽  
Author(s):  
C. C. Koch
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Axial Flow ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Low Speed ◽  
Axial Flow Compressor ◽  
Wide Range ◽  
Flow Compressor

A procedure for estimating the maximum pressure rise potential of axial flow compressor stages is presented. A simplified stage average pitchline approach is employed so that the procedure can be used during a preliminary design effort before detailed radial distributions of blading geometry and fluid parameters are established. Semi-empirical correlations of low speed experimental data are presented that relate the stalling static-pressure-rise coefficient of a compressor stage to cascade passage geometry, tip clearance, bladerow axial spacing and Reynolds number. Blading aspect ratio is accounted for through its effect on normalized clearances, Reynolds number and wall boundary layer blockage. An unexpectedly strong effect of airfoil stagger and of the resulting flow coefficient of the stage’s vector triangle is observed in the experimental data. This is shown to be caused by the differing ability of different types of stage vector triangles to re-energize incoming low-momentum fluid. Use of a suitable “effective” dynamic head in the pressure rise coefficient gives a good correlation of this effect. Stalling pressure rise data from a wide range of both low speed and high speed compressor stages are shown to be in good agreement with these correlations.

A Study of Flow of Plastics Through Pipes

1946 ◽  
Vol 13 (2) ◽  
pp. A101-A105
Author(s):  
R. C. Binder ◽  
J. E. Busher
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Friction Coefficient ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Dynamic Viscosity ◽  
Apparent Viscosity ◽  
Turbulent Viscosity ◽  
Yield Value

Abstract The pipe friction coefficient for true fluids is usually expressed as a function of Reynolds number. This method of organizing data has been extended to tests on the flow of different suspensions which behaved as ideal plastics in the laminar-flow range and as true fluids in the turbulent-flow range. In the laminar-flow range, Reynolds number below about 2100, the denominator in Reynolds number is taken as the apparent viscosity. The apparent viscosity can be determined from the yield value and the coefficient of rigidity. In the turbulent-flow range, the denominator in Reynolds number is an equivalent or turbulent viscosity equal to the dynamic viscosity of a true fluid having the same friction coefficient, velocity, diameter, and density as that of the plastic. The various experimental data on plastics correlate well with this extension of the method for true fluids.

Effect of Size and Slip Coefficient of a Porous Manifold on Thermal Stratification in Storage Tanks

2009 ◽  
Author(s):  
N. M. Brown ◽  
F. C. Lai
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Simulations ◽  
Storage Tank ◽  
Richardson Number ◽  
Thermal Stratification ◽  
Temperature Fields ◽  
Storage Tanks ◽  
Slip Coefficient ◽  
Wide Range

Numerical simulations have been performed to study the effects of size and slip coefficient of a porous manifold on the thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 &lt; Gr &lt; 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 10−2 &lt; Ri &lt; 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.

A One-Dimensional Numerical Model for the Momentum Exchange in Regenerative Pumps

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Francis J. Quail ◽  
Matthew Stickland ◽  
Armin Baumgartner
Keyword(s):  
Experimental Data ◽  
Low Flow ◽  
Correction Factors ◽  
Momentum Exchange ◽  
Pump Design ◽  
Pump Performance ◽  
One Dimensional ◽  
Geometry Model ◽  
Wide Range ◽  
Dimensional Models

The regenerative pump is a rotor-dynamic turbomachine capable of developing high heads at low flow rates and low specific speeds. In spite of their low efficiency, usually less than 50%, they have found a wide range of applications as compact single-stage pumps with other beneficial features. The potential of a modified regenerative pump design is presented for the consideration of the performance improvements. In this paper the fluid dynamic behavior of the novel design was predicted using a one-dimensional model developed by the authors. Unlike most one-dimensional models previously published for regenerative pumps, the momentum exchange is numerically computed. Previous one-dimensional models relied on experimental data and correction factors; the model presented in this paper demonstrates an accurate prediction of the pump performance characteristics without the need for correction with experimental data. The validity of this approach is highlighted by the comparison of computed and measured results for two different regenerative pump standards. The pump performance is numerically assessed without the need of correction factors or other experimental data. This paper presents an approach for regenerative pumps using a physically valid geometry model and by resolving the circulatory velocity in the peripheral direction.

Numerical Prediction of Turbulent Flow in Rotating Cavities

1988 ◽  
Vol 110 (2) ◽  
pp. 202-211 ◽  
Author(s):  
A. P. Morse
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Predictive Accuracy ◽  
Turbulent Transport ◽  
Reynolds Numbers ◽  
Spreading Rate ◽  
Flow Conditions ◽  
Wide Range ◽  
Ekman Layers ◽  
Radial Outflow

Predictions of the isothermal, incompressible flow in the cavity formed between two corotating plane disks and a peripheral shroud have been obtained using an elliptic calculation procedure and a low turbulence Reynolds number k–ε model for the estimation of turbulent transport. Both radial inflow and outflow are investigated for a wide range of flow conditions involving rotational Reynolds numbers up to ∼106. Although predictive accuracy is generally good, the computed flow in the Ekman layers for radial outflow often displays a retarded spreading rate and a tendency to laminarize under conditions that are known from experiment to produce turbulent flow.

Predictive Model for Two-Phase Flow Performance of Mixed Flow Pumps

2019 ◽  
Author(s):  
Abhay Patil ◽  
Burak Ayyildiz ◽  
Sahand Pirouzpanah ◽  
Adolfo Delgado ◽  
Gerald Morrison
Keyword(s):  
Experimental Data ◽  
Prediction Models ◽  
Two Phase Flow ◽  
Oil And Gas Industry ◽  
Systematic Change ◽  
Phase Flow ◽  
Dimensionless Numbers ◽  
Two Phase ◽  
Pump Design ◽  
Flow Interaction

Abstract Multiphase pumps are increasingly being used to transport gas-liquid multiphase flow in the oil and gas industry. Complexity of two-phase flow interaction and varying designs of multiphase pumps pose significant challenges to developing generalized performance prediction tool similar to the affinity laws. The goal of this study is to characterize the performance of two multiphase pumps with different specific speeds using experimental data to develop generalized prediction models. Initially, the performance is investigated in the terms of head, power input and efficiency for different Gas Volume Fractions (GVF). Dimensional analysis is performed to evaluate the effect of pump geometry and GVF. Head degradation due to the presence of gas is presented in the terms of dimensionless numbers. These numbers represent the systematic change in the energy loss due to two phase flow interaction and inherent characteristics of the pump design. This is utilized to develop a generalized model for two phase flow. The study is concluded by validating the model using experimental data.

Partially filled pipes: experiments in laminar and turbulent flow

2018 ◽  
Vol 848 ◽  
pp. 467-507 ◽  
Author(s):  
Henry C.-H. Ng ◽  
Hope L. F. Cregan ◽  
Jonathan M. Dodds ◽  
Robert J. Poole ◽  
David J. C. Dennis
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Turbulent Flow ◽  
Pipe Flow ◽  
Large Scale ◽  
Open Channel ◽  
Streamwise Velocity ◽  
Flow Depth ◽  
Secondary Motion ◽  
Laminar And Turbulent Flow

Pressure-driven laminar and turbulent flow in a horizontal partially filled pipe was investigated using stereoscopic particle imaging velocimetry (S-PIV) in the cross-stream plane. Laminar flow velocity measurements are in excellent agreement with a recent theoretical solution in the literature. For turbulent flow, the flow depth was varied independently of a nominally constant Reynolds number (based on hydraulic diameter, $D_{H}$; bulk velocity, $U_{b}$ and kinematic viscosity $\unicode[STIX]{x1D708}$) of $Re_{H}=U_{b}D_{H}/\unicode[STIX]{x1D708}\approx 30\,000\pm 5\,\%$. When running partially full, the inferred friction factor is no longer a simple function of Reynolds number, but also depends on the Froude number $Fr=U_{b}/\sqrt{gD_{m}}$ where $g$ is gravitational acceleration and $D_{m}$ is hydraulic mean depth. S-PIV measurements in turbulent flow reveal the presence of secondary currents which causes the maximum streamwise velocity to occur below the free surface consistent with results reported in the literature for rectangular cross-section open channel flows. Unlike square duct and rectangular open channel flow the mean secondary motion observed here manifests only as a single pair of vortices mirrored about the vertical bisector and these rollers, which fill the half-width of the pipe, remain at a constant distance from the free surface even with decreasing flow depth for the range of depths tested. Spatial distributions of streamwise Reynolds normal stress and turbulent kinetic energy exhibit preferential arrangement rather than having the same profile around the azimuth of the pipe as in a full pipe flow. Instantaneous fields reveal the signatures of elements of canonical wall-bounded turbulent flows near the pipe wall such as large-scale and very-large-scale motions and associated hairpin packets whilst near the free surface, the signatures of free surface turbulence in the absence of imposed mean shear such as ‘upwellings’, ‘downdrafts’ and ‘whirlpools’ are present. Two-point spatio-temporal correlations of streamwise velocity fluctuation suggest that the large-scale coherent motions present in full pipe flow persist in partially filled pipes but are compressed and distorted by the presence of the free surface and mean secondary motion.

Thermal Stress Analysis and Determination of Stitching Pattern Effect on Aerodynamics of a Soccer Ball

2017 ◽  
Author(s):  
Mosfequr Rahman ◽  
Sirajus Salekeen ◽  
Asher Holland ◽  
Todd Nixon ◽  
Hunter Kight ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Thermal Stress ◽  
Turbulent Flow ◽  
Stress Analysis ◽  
Drag Force ◽  
Normal Condition ◽  
Soccer Ball ◽  
Thermal Stress Analysis ◽  
Maximum Deformation ◽  
Wide Range

Soccer is played all over the world in a wide range of temperature environments. One of the objectives of this numerical study is to determine whether temperature has an effect on the body and performance of a soccer ball. Another object is to aerodynamically determine the effect of stitching pattern of the ball on its flight. The soccer ball was modeled in ANSYS Workbench and tested with thermal-stress analysis tool at nominal temperatures of 0°C, 20°C, and 40°C. The maximum deformation of a soccer ball at normal condition occurred at 40°C which was 1.0503 cm as compared to the 0.9587 cm at 0°C. This normal condition means when the ball is subjected to an internal pressure of 80 kPa which is the standard inflation pressure. When an external 2700 Pa pressure was applied to the soccer ball which is the average force of a kick, the maximum deformation again occurred at 40°C which was 5.2289 cm as compared to the 4.7599 cm at 0°C. Therefore, the stiffness of the ball materials decreased as the temperature increased. This reveals that the ball delivers a greater force at the surface of contact when the temperature drops. The second part of this study as mentioned earlier was to study the aerodynamic effect on a soccer ball traveling through the air at a certain speed. Two types of soccer ball were analyzed for this reason to see which of the two flew better in the air. The two types were a regular FIFA soccer ball with stitching and a normal soccer ball without stitching. Two tests were performed on both types of the soccer ball. These tests were done using ANSYS FLUENT and the sought out output parameters were velocity, pressure, Reynolds Number and drag force. In the first test the soccer balls were rotating in the air and in the second test the soccer balls were not rotating in the air. For the first test, the ball without stitching had the higher velocity, Reynolds Number, and drag force, which were 126.2 m/s, 2.420 × 106, and 122.6 N respectively. This means the ball without stitching is experiencing a more random turbulent flow and is being pulled more into the direction of the drag force. This happens because the soccer ball without stitching will rotate faster and won’t have stitching patterns to create friction that will slow down the flow. For the second test, the ball with stitching had the higher velocity, Reynolds Number and drag force which were 42.22 m/s, 8.095 × 105, and 16.81 N respectively. This means the soccer ball with stitching is experiencing a random turbulent flow and is being pulled in the direction of the drag force because the stitching patterns are not in complete contact with the air to create friction.

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