Investigation of Multiphase Unsteady Flow in a Double-Channel Pump by CFD Simulation and PIV Measurement

2012 ◽  
Author(s):  
Binjuan Zhao ◽  
Shouqi Yuan ◽  
Zhongfu Huang ◽  
Duohua Hou
Keyword(s):  
Unsteady Flow ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Tetrahedral Mesh ◽  
Data Set ◽  
Pressure Surface ◽  
Piv Measurement ◽  
Double Channel

The multiphase unsteady flow fields in a double-channel pump have been investigated both numerically and experimentally for the design condition and also off-design conditions. Three-dimensional, unsteady Reynolds-averaged Navier–Stokes equations are solved on high-quality unstructured tetrahedral mesh with the shear stress transport turbulence model by using the CFD code Fluent 6.4. Furthermore, PIV measurements are successfully conducted in the impeller, in order to capture the complex flow with abundant measurement data and to validate the CFD results. The main conclusions include: 1) The velocity field changes according to the blade orientation. When the impeller channel is near to the outlet of volute, the velocity distribution is relatively regular than when the impeller channel is far from the outlet of volute. 2) At the tongue of the volute, the fluid discharged from the impeller mixes with the re-circulating fluid in the volute, which contributes a lot to the impeller-volute interaction. 3) The pressure vibration in the volute is very obvious, pressure fluctuation on monitors far from the volute outlet is more obvious than those near to the volute outlet, and becomes stronger as drawing near the tongue. 4) The sand volume fraction distribution is extremely inhomogeneous in both impeller and volute. Particles mainly flow along the pressure surface and hub of the impeller; Particles mainly accumulate in the region near to the exit of volute, and the largest sand volume fraction is observed at the tongue. 5) Particle diameter has great influence on the particle distribution, and particles tend to accumulate on the pressure surface of the balde with the increase of particle diameter. 6) The total pressure difference of the pump declines with the increase of inlet sandy volume fraction or particle diameter. 7) PIV measurement results correspond well with the CFD simulation results, which in turn gives a good validation of the simulation accuracy. This work offers a good data set to develop the comprehension of the unsteady multiphase flow in the double-channel pump.

The Influence of Major Diameter Solid Particle on the Double-Channel Pump Performance

2011 ◽  
Author(s):  
Yi Li ◽  
Qiaoling Cui ◽  
Zuchao Zhu ◽  
Zhaohui He ◽  
Baoling Cui
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Sliding Wear ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Diameter ◽  
Wall Region ◽  
Impeller Outlet ◽  
Anticlockwise Direction ◽  
Double Channel

Based on mixture model, the numerical simulation of solid-liquid two-phase flow in a double channel pump (Specific speed ns = 81) was carried out. The effects of particle diameter, particle volume fraction and flow rate on solid volume concentration distribution, relative velocity distribution and abrasion characteristics were studied. The results reveal that in the impeller, more particles concentrate at the nut of the shaft end and the edge of the impeller outlet. So those regions are worn seriously. The abrasive types are sliding wear on the impeller outlet edge and impact wear on the nut respectively. In the wall of the volute, the concentrated areas of particles move round the anticlockwise direction when the mixture flow rate is larger. The reason is the mixture velocity is larger as the flow rate increases, and meanwhile the centrifugal force and gravity force are invariable. So the particles move round the impeller rotational direction consequently. In the volute, particles concentrate on the tongue and wall region, especially on the sections I, II, V and VII. So the areas are easily worn out. The abrasive type is the heavy sliding wear in the volute wall. Numerical simulation results are consistent with the actual situation. It follows that the calculating method is feasible.

Investigation of Periodically Unsteady Flow in a Radial Pump by CFD Simulations and LDV Measurements

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Unsteady Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Measurement Data ◽  
Load Condition ◽  
Navier Stokes ◽  
Complex Flow ◽  
Data Set ◽  
Vaned Diffuser ◽  
Radial Pump

The periodically unsteady flow fields in a low specific speed radial diffuser pump have been investigated both numerically and experimentally for the design condition (Qdes) and also one part-load condition (0.5Qdes). Three-dimensional, unsteady Reynolds-averaged Navier–Stokes equations are solved on high-quality structured grids with the shear stress transport turbulence model by using the CFD (computational fluid dynamics) code CFX-10. Furthermore, two-dimensional laser Doppler velocimetry (LDV) measurements are successfully conducted in the interaction region between the impeller and the vaned diffuser, in order to capture the complex flow with abundant measurement data and to validate the CFD results. The analysis of the obtained results has been focused on the behavior of the periodic velocity field and the turbulence field, as well as the associated unsteady phenomena due to the unsteady interaction. In addition, the comparison between CFD and LDV results has also been addressed. The blade orientation effects caused by the impeller rotation are quantitatively examined and detailedly compared with the turbulence effect. This work offers a good data set to develop the comprehension of the impeller-diffuser interaction and how the flow varies with relative impeller position to the diffuser in radial diffuser pumps.

Unsteady Isothermal Flow Through a Staggered Tube Bundle Array

2012 ◽  
Author(s):  
Artit Ridluan ◽  
Surasing Arayangkun ◽  
Coochart Phayom
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Cfd Simulation ◽  
Transient Flow ◽  
Stokes Equations ◽  
Tube Bundle ◽  
Separation Bubble ◽  
Reynolds Numbers ◽  
Isothermal Flow ◽  
Flow Through

Two-dimensional Unsteady simulations of isothermal flow through a staggered tube bundle array at three different Reynolds numbers 54, 72, and 90 were investigated. The Navier-Stokes equations are numerically solved. Based on the CFD simulation results, the unsteady flow patterns were developed behind the rear row of the array, while for the other rows, the steady separated and reattached flow behaviors were observed, small, short, and closed separation bubble behind the rods. At Reynolds Number of 54, the transient flow was perfectly periodic. The complicated patterns of unsteady flow could be observed at Reynolds numbers of 72 and 90. The shedding patterns of vortices from the last rods were different and no longer periodic as found at Reynolds number of 54. The degree of chaos is increased as Reynolds number progressed.

Investigation of Numerical and Physical Modelling Effects on the CFD Simulation of the Unsteady Flow in a HPT Stage

2003 ◽  
Author(s):  
P. de la Calzada ◽  
J. Ferna´ndez-Castan˜eda
Keyword(s):  
Unsteady Flow ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Physical Modelling ◽  
High Sensitivity ◽  
Potential Interaction ◽  
Navier Stokes ◽  
Test Case ◽  
Viscous Effects ◽  
Navier Stokes Equations

In order to investigate the unsteady flow behaviour in an HPT stage and the effects on the CFD solution of some numerical and physical modelling assumptions usually undertaken by the engineering community, an ITP in-house unsteady CFD code called Mu2s2T is first validated and then run under different configurations. The code is a fully unstructured code which solves the Reynolds averaged Navier-Stokes equations with a k-ω turbulence model. Hybrid meshes are used by having semi-structured meshes along the profile wall and fully unstructured triangular meshes on the inviscid region. The VKI Brite Euram transonic turbine stage experimental test case is used for the investigation. This turbine is representative of a state of the art HPT and presents high potential interaction due to the vane shock waves. After validating the code in this case, the influence of typical engineering assumptions is investigated. First the influence of the rotor stagger angle is analysed, resulting in a high sensitivity of the predicted pressure level at the front part of the blade and a better matching with the experimental data when an opening of 1° is applied. The influence in the solution of applying an integer airfoil count ratio compared with the solution with exact number off computed by means of phase lagged boundary conditions is also investigated. Additional Euler and Navier-Stokes computations are presented and the influence of the viscous effects is discussed. Finally a simulation including vane trailing edge cooling is performed so that conclusions about the influence of the cooling can be drawn.

scholarly journals Computational Modeling of Flow Characteristics in Three Products Hydrocyclone Screen

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1295
Author(s):  
Anghong Yu ◽  
Chuanzhen Wang ◽  
Haizeng Liu ◽  
Md. Shakhaoath Khan
Keyword(s):  
Static Pressure ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Pressure Profile ◽  
Reynolds Stress Model ◽  
Grid Scheme ◽  
Cylindrical Screen ◽  
The Right ◽  
Axial Depth

Three products hydrocyclone screen (TPHS) can be considered as the combination of a conventional hydrocyclone and a cylindrical screen. In this device, particles are separated based on size under the centrifugal classification coupling screening effect. The objective of this work is to explore the characteristics of fluid flow in TPHS using the computational fluid dynamics (CFD) simulation. The 2 million grid scheme, volume fraction model, and linear pressure–strain Reynolds stress model were utilized to generate the economical grid-independence solution. The pressure profile reveals that the distribution of static pressure was axisymmetric, and its value was reduced with the increasing axial depth. The maximum and minimum were located near the tangential inflection point of the feed inlet and the outlets, respectively. However, local asymmetry was created by the left tangential inlet and the right screen underflow outlet. Furthermore, at the same axial height, the static pressure gradually decreased along the wall to the center. Near the cylindrical screen, the pressure difference between the inside and the outside cylindrical screen dropped from positive to negative as the axial depth increased from −35 to −185 mm. Besides, TPHS shows similar distributions of turbulence intensity I, turbulence kinetic energy k, and turbulence dissipation rate ε; i.e., the values fell with the decrease in axial height. Meanwhile, from high to low, the pressure values are distributed in the feed chamber, the cylindrical screen, and conical vessel; the value inside the screen was higher than the outer value.

An Efficient Immersed Boundary Method Based on Penalized Direct Forcing for Simulating Flows Through Real Porous Media

2012 ◽  
Author(s):  
Wim-Paul Breugem ◽  
Vincent van Dijk ◽  
René Delfos
Keyword(s):  
Porous Medium ◽  
Ct Scan ◽  
Immersed Boundary Method ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Immersed Boundary ◽  
Average Particle ◽  
Boundary Method ◽  
Direct Forcing

A computationally efficient Immersed Boundary Method (IBM) based on penalized direct forcing was employed to determine the permeability of a real porous medium. The porous medium was composed of about 9000 glass beads with an average particle diameter of 1.93 mm and a porosity of 0.367. The forcing of the IBM depends on the local solid volume fraction within a computational grid cell. The latter could be obtained from a high-resolution X-ray Computed Tomography (CT) scan of the packing. An experimental facility was built to determine the permeability of the packing experimentally. Numerical simulations were performed for the same packing based on the data from the CT scan. For a scan resolution of 0.1 mm the numerical value for the permeability was nearly 70% larger than the experimental value. An error analysis indicated that the scan resolution of 0.1 mm was too coarse for this packing.

Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

2011 ◽  
Vol 24 (6) ◽  
pp. 777-788 ◽  
Author(s):  
J.Z. Liang
Keyword(s):  
Polymer Composites ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Interfacial Structure ◽  
Interlayer Thickness ◽  
Filled Polymer ◽  
Mechanical And Physical Properties ◽  
The Relationship ◽  
Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

scholarly journals On the Accelerated Settling of Fine Particles in a Bidisperse Slurry

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Leonid L. Minkov ◽  
Yuliya O. Stepanova ◽  
Johann Dueck ◽  
Elizaveta V. Pikushchak
Keyword(s):  
Fine Particles ◽  
Stokes Equations ◽  
Fine Fraction ◽  
Particle Diameter ◽  
Sedimentation Velocity ◽  
Navier Stokes ◽  
Circulation Zone ◽  
Navier Stokes Equations ◽  
Volume Average ◽  
Bidisperse Suspension

An estimation of increasing the volume average sedimentation velocity of fine particles in bidisperse suspension due to their capturing in the circulation zone formed in the laminar flow of incompressible viscous fluid around the spherical coarse particle is proposed. The estimation is important for an explanation of the nonmonotonic shape of the separation curve observed for hydrocyclones. The volume average sedimentation velocity is evaluated on the basis of a cellular model. The characteristic dimensions of the circulation zone are obtained on the basis of a numerical solution of Navier-Stokes equations. Furthermore, these calculations are used for modelling the fast sedimentation of fine particles during their cosedimentation in bidisperse suspension. It was found that the acceleration of sedimentation of fine particles is determined by the concentration of coarse particles in bidisperse suspension, and the sedimentation velocity of fine fraction is proportional to the square of the coarse and fine particle diameter ratio. The limitations of the proposed model are ascertained.

A 3D Unsteady Flow Analysis in a Doubly Constricted Tube

2000 ◽  
Author(s):  
B. V. Rathish Kumar ◽  
T. Yamaguchi ◽  
H. Liu ◽  
R. Himeno
Keyword(s):  
Pressure Drop ◽  
Unsteady Flow ◽  
Stokes Equations ◽  
Vortex Formation ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
In Series ◽  
3D Unsteady Flow

Abstract Unsteady flow dynamics in a doubly constricted vessel is analyzed by using a time accurate Finite Volume solution of three dimensional incompressible Navier-Stokes equations. Computational experiments are carried out for various values of Reynolds number in order to assess the criticality of multiple mild constrictions in series and also to bring out the subtle 3D features like vortex formation. Studies reveal that pressure drop across a series of mild constrictions can get physiologically critical. Further this pressure drop is found to be sensitive to the spacing between the constrictions and also to the oscillatory nature of the inflow profile.

A COMPARATIVE STUDY OF MULTIPLE REGRESSION AND MACHINE LEARNING TECHNIQUES FOR PREDICTION OF NANOFLUID HEAT TRANSFER

2021 ◽  
pp. 1-22
Author(s):  
Eyup Kocak ◽  
Ulku Ece Ayli ◽  
Hasmet Turkoglu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Multiple Regression ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Machine Learning Techniques ◽  
Exponential Factor ◽  
Nano Fluid ◽  
Neuro Fuzzy ◽  
Interface System

Abstract The aim of this paper is to introduce and discuss prediction power of the multiple regression technique, Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Interface System (ANFIS) methods for predicting the forced convection heat transfer characteristics of a turbulent nano fluid flow a pipe. Water and Al2O3 mixture is used as the nano fluid. Utilizing FLUENT software, numerical computations were performed with volume fraction ranging between 0.3% and 5%, particle diameter ranging between 20 and 140 nm and Reynolds number ranging between 7000 and 21000. Based on the computationally obtained results, a correlation is developed for Nusselt number using the multiple regression method. Also, based on the CFD results different ANN architectures with different number of neurons in the hidden layers and several training algorithms (Levenberg-Marquardt, Bayesian Regularization, Scaled Conjugate Gradient) are tested to find the best ANN architecture. In addition, Adaptive Neuro-fuzzy Interface System (ANFIS) is also used to predict the Nusselt number. In the ANFIS, number of clusters, exponential factor and Membership Function (MF) type are optimized. The results obtained from multiple regression correlation, ANN and ANFIS were compared. According to the obtained results, ANFIS is a powerful tool with a R2 of 0.9987 for predictions.

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