Quantitative Visualization of the Flow Within the Volute of a Centrifugal Pump. Part B: Results and Analysis

1992 ◽  
Vol 114 (3) ◽  
pp. 396-403 ◽  
Author(s):  
R. Dong ◽  
S. Chu ◽  
J. Katz
Keyword(s):  
Angular Momentum ◽  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Momentum Flux ◽  
Inflow Rate ◽  
Impeller Blade ◽  
Velocity Fluctuations ◽  
Quantitative Visualization ◽  
The Mean

PDV is used for measuring the velocity within the volute of a centrifugal pump at different impeller blade orientations, on and off design conditions. It is demonstrated that the flow is “pulsating” and depends on the location of the blade relative to the tongue. The leakage also depends on blade orientation and increases with decreasing flow rate. The velocity near the impeller is dominated by the jet/wake phenomenon. Differences in the outflux from the impeller, resulting from changes inflow rate, occur primarily near the exit. Away from the tongue the distributions of vθ mostly agrees with the assumption that vθ ∝ 1/r. Sites prone to high velocity fluctuations include the blade wake, interface between the jet and the wake and near the tongue. Angular momentum and kinetic energy fluxes, turbulent stresses and tubulence production are also computed. It is shown that at the same θ the momentum flux can increase near the impeller and decrease at the perimeter. Consequently, the mean flux cannot be used for estimating conditions near the impeller. Torques caused by τrθ and τθθ can be as high as 2 and 5 percent of the change in angular momentum flux, respectively.

scholarly journals A Comparative Assessment of Spalart-Shur Rotation/Curvature Correction in RANS Simulations in a Centrifugal Pump Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang
Keyword(s):  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Comparative Assessment ◽  
Turbulence Kinetic Energy ◽  
Low Flow ◽  
Pump Impeller ◽  
Curvature Correction ◽  
Centrifugal Pump Impeller ◽  
Low Flow Rate

RANS simulation is widely used in the flow prediction of centrifugal pumps. Influenced by impeller rotation and streamline curvature, the eddy viscosity models with turbulence isotropy assumption are not accurate enough. In this study, Spalart-Shur rotation/curvature correction was applied on the SSTk-ωturbulence model. The comparative assessment of the correction was proceeded in the simulations of a centrifugal pump impeller. CFD results were compared with existing PIV and LDV data under the design and low flow rate off-design conditions. Results show the improvements of the simulation especially in the situation that turbulence strongly produced due to undesirable flow structures. Under the design condition, more reasonable turbulence kinetic energy contour was captured after correction. Under the low flow rate off-design condition, the prediction of turbulence kinetic energy and velocity distributions became much more accurate when using the corrected model. So, the rotation/curvature correction was proved effective in this study. And, it is also proved acceptable and recommended to use in the engineering simulations of centrifugal pump impellers.

Quantitative Visualization of the Flow Within the Volute of a Centrifugal Pump. Part A: Technique

1992 ◽  
Vol 114 (3) ◽  
pp. 390-395 ◽  
Author(s):  
R. Dong ◽  
S. Chu ◽  
J. Katz
Keyword(s):  
Centrifugal Pump ◽  
Particle Concentration ◽  
Mean Shift ◽  
Pulsed Laser ◽  
Particle Displacement ◽  
Quantitative Visualization ◽  
The Mean ◽  
Visualization Experiments ◽  
Neutrally Buoyant ◽  
Quantitative Flow Visualization

This paper describes a series of quantitative flow visualization experiments within the volute of a centrifugal pump by implementing the “Particle Displacement Velocimetry” method (PDV or PIV). Part A focuses on the measurement procedures and includes an uncertainty analysis. This technique involves illuminating sections of a flow field with pulsed laser sheets while seeding the water with microscopic, neutrally buoyant particles containing imbedded fluorescent dye. By pulsing the laser more than once while recording a single photograph each particle leaves multiple traces on the same film. The analysis procedures consist of dividing the image to a large number of small sections (windows) and computing of the mean shift of all particles within each window. This shift is determined by computing the autocorrelation function of the image within the window. Digital image processing and specially written software are being utilized while analyzing the data. It is demonstrated that by controlling the magnification and particle concentration, the relative error can be maintained at about 1 percent. A sample analyzed image is presented. The rest of the data are included in Part B.

Pseudo-turbulent gas-phase velocity fluctuations in homogeneous gas–solid flow: fixed particle assemblies and freely evolving suspensions

2015 ◽  
Vol 770 ◽  
pp. 210-246 ◽  
Author(s):  
M. Mehrabadi ◽  
S. Tenneti ◽  
R. Garg ◽  
S. Subramaniam
Keyword(s):  
Kinetic Energy ◽  
Phase Velocity ◽  
Turbulent Kinetic Energy ◽  
Gas Phase ◽  
Reynolds Stress ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Velocity Fluctuations ◽  
The Mean ◽  
Particle Assemblies

Gas-phase velocity fluctuations due to mean slip velocity between the gas and solid phases are quantified using particle-resolved direct numerical simulation. These fluctuations are termed pseudo-turbulent because they arise from the interaction of particles with the mean slip even in ‘laminar’ gas–solid flows. The contribution of turbulent and pseudo-turbulent fluctuations to the level of gas-phase velocity fluctuations is quantified in initially ‘laminar’ and turbulent flow past fixed random particle assemblies of monodisperse spheres. The pseudo-turbulent kinetic energy $k^{(f)}$ in steady flow is then characterized as a function of solid volume fraction ${\it\phi}$ and the Reynolds number based on the mean slip velocity $\mathit{Re}_{m}$. Anisotropy in the Reynolds stress is quantified by decomposing it into isotropic and deviatoric parts, and its dependence on ${\it\phi}$ and $Re_{m}$ is explained. An algebraic stress model is proposed that captures the dependence of the Reynolds stress on ${\it\phi}$ and $Re_{m}$. Gas-phase velocity fluctuations in freely evolving suspensions undergoing elastic and inelastic particle collisions are also quantified. The flow corresponds to homogeneous gas–solid systems, with high solid-to-gas density ratio and particle diameter greater than dissipative length scales. It is found that for the parameter values considered here, the level of pseudo-turbulence differs by only 15 % from the values for equivalent fixed beds. The principle of conservation of interphase turbulent kinetic energy transfer is validated by quantifying the interphase transfer terms in the evolution equations of kinetic energy for the gas-phase and solid-phase fluctuating velocity. It is found that the collisional dissipation is negligible compared with the viscous dissipation for the cases considered in this study where the freely evolving suspensions attain a steady state starting from an initial condition where the particles are at rest.

scholarly journals Analysis of the number and angle of the impeller blade to the performance of centrifugal pump

2021 ◽  
pp. 62-68
Author(s):  
Sugeng Hadi Susilo ◽  
Agus Setiawan
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Flow Simulation ◽  
Maximum Output ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Pump Performance ◽  
Solid Works ◽  
Discharge Pressure

The paper discusses the performance of the pump in relation to the impeller. The impeller section is determined by the number and angle of the blades. Therefore, the purpose of this study was to analyze the role of the number and angle of impeller blades on the performance (discharge and discharge pressure) of centrifugal pumps based on experiments and simulations. The method used is experiment and simulation. Using a centrifugal pump type GWP 20/4 SW, Maximum Output: 6.5 HP/3500 rpm, Inlet/Outlet: 2 Inch, Dimensions: 475x375x370 mm. Experiments and simulations by varying the number of blades 2, 4, and 6 with a blade tilt angle of 130°, 150°, and 160°. For flow simulation using solid works program. The results show that pump performance is related to discharge pressure, impeller with 2-blades and an angle of 130° the pressure increases 0.45–2.45 bar, for 150° increases 0.14–2.96 bar, and 160° increases 0.29–3.07 bars. For a 4-blade impeller and an angle of 130°, the pressure increases by 0.48–3.12 bar, for 150° it increases by 0.39–3.39 bar, and for 160° it increases by 0.36–3.48 bar. While the impeller for 6-blades with an angle of 130° the pressure increases from 0.6 bar to 3.72 bar, for 150° increases from 1.36 to 4.34 bar, and 160° increases by 0.36–4.74 bar. While it related pump performance to flow rate, increasing the number of blades causes a decrease in flow rate. The highest flow rate is in a 2-blade impeller with a blade angle of 130° is 404.91 l/s. The lowest flow rate is on a 6-blade impeller with an angle of 160° is 279.66 l/s

Theoretical Investigation on Flow Rate at the Maximum Efficiency Point in the Design of Impeller Blade in Centrifugal Pump

2004 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Pump ◽  
Theoretical Investigation ◽  
Flow Rate ◽  
Tangential Velocity ◽  
Maximum Efficiency ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Peripheral Velocity ◽  
Impeller Outlet ◽  
Fluid Particles

This paper presents a theoretical investigation of the flow rate at the maximum efficiency point in the design of impeller blade in centrifugal pump. An energy balance was performed at the trailing edge of impeller outlet in the rotating flow passage of centrifugal pump. The evaluation shows that, when the fluid particles straight forward tangential velocity is one third of the impeller blade’s peripheral velocity and the fluid particles circular forward tangential velocity is two third of the impeller blade’s peripheral velocity at the trailing edge of the impeller outlet, the maximum hydraulic energy output, that is, the maximum efficiency point is obtained.

Quantitative Visualization of the Flow in a Centrifugal Pump With Diffuser Vanes—I: On Flow Structures and Turbulence

1999 ◽  
Vol 122 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Manish Sinha ◽  
Joseph Katz
Keyword(s):  
Centrifugal Pump ◽  
Layer Structure ◽  
Digital Camera ◽  
Flow Structures ◽  
Impeller Blade ◽  
Vaned Diffuser ◽  
Custom Made ◽  
Quantitative Visualization ◽  
Entire Flow ◽  
The Impact

Particle image velocimetry measurements are used to identify the unsteady flow structures and turbulence in a transparent centrifugal pump with a vaned diffuser. The experiments are being performed in a special facility that enables simultaneous measurements of the flow between the impeller blades, the gap between the impeller and the diffuser, between the diffuser vanes and in the volute. A custom-made 2 K×2 K digital camera with a unique digital image-shifting feature is used to record the images. For the measurements made close to design conditions, phase averaged velocity and vorticity fields are presented along with the corresponding turbulent stresses at different impeller blade orientations (relative to diffuser vanes). The statistically converged results show that the entire flow field is dominated by wakes generated by impeller blades, diffuser vanes, and unsteady separation phenomena. The boundary layer structure in the diffuser and the associated turbulence are strongly affected by the unsteadiness generated by the impeller. The impact of the impeller blade orientation includes direct effects, jetting ahead and a trailing wake behind the blade, as well as indirect effects, such as two types of flow separation within the diffuser. The cyclic variations are higher (typically twice) than the turbulent fluctuations within the impeller and between the diffuser vanes, but decrease below the turbulence level with increasing distance downstream of the trailing edge of the diffuser vanes. [S0098-2202(00)00801-4]

A Consideration on Energy Transfer Mechanism Caused Between Impeller Blade and a Fluid Particle in Centrifugal Pump

2002 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Pump ◽  
Centrifugal Force ◽  
Flow Rate ◽  
Fluid Particle ◽  
Rotating Flow ◽  
Energy Transfer Mechanism ◽  
Forward Movement ◽  
Impeller Blade ◽  
Impeller Outlet ◽  
Centripetal Forces

Impeller blade’s rotational motion causes centrifugal force on fluid particle. It directs radial outward. However, the flow rate, that is, radial outward flow is not caused by centrifugal force in centrifugal pump. Tangential forward force, which is in the direction perpendicular to rotational radius, causes tangential forward movement on fluid particle under the radial balance of centrifugal and centripetal forces in the rotating flow passage of centrifugal pump and it causes the flow rate. And the head is caused by centrifugal force and equivalent to centripetal force, which acts on fluid particle radial inward. Which is equivalent to external force at the trailing edge of impeller outlet.

The flow of liquid in a stream from the standard turbine impeller

1979 ◽  
Vol 44 (3) ◽  
pp. 700-710 ◽  
Author(s):  
Ivan Fořt ◽  
Hans-Otto Möckel ◽  
Jan Drbohlav ◽  
Miroslav Hrach
Keyword(s):  
Reynolds Number ◽  
Kinematic Viscosity ◽  
Momentum Flux ◽  
Relative Size ◽  
Mean Velocity ◽  
Axial Profile ◽  
The Mean ◽  
Hot Film ◽  
Turbine Impeller

Profiles of the mean velocity have been analyzed in the stream streaking from the region of rotating standard six-blade disc turbine impeller. The profiles were obtained experimentally using a hot film thermoanemometer probe. The results of the analysis is the determination of the effect of relative size of the impeller and vessel and the kinematic viscosity of the charge on three parameters of the axial profile of the mean velocity in the examined stream. No significant change of the parameter of width of the examined stream and the momentum flux in the stream has been found in the range of parameters d/D ##m <0.25; 0.50> and the Reynolds number for mixing ReM ##m <2.90 . 101; 1 . 105>. However, a significant influence has been found of ReM (at negligible effect of d/D) on the size of the hypothetical source of motion - the radius of the tangential cylindrical jet - a. The proposed phenomenological model of the turbulent stream in region of turbine impeller has been found adequate for values of ReM exceeding 1.0 . 103.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

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