Numerical Investigations of Gas–Liquid Two-Phase Flow in a Pump Inducer

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Michael Mansour ◽  
Trupen Parikh ◽  
Sebastian Engel ◽  
Dominique Thévenin
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Pressure Change ◽  
Positive Influence ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Part Load ◽  
Gas Volume

Abstract Inducers show generally a positive influence on the performance of centrifugal pumps in the two-phase regime, since they produce more uniform mixtures and increase the pressure before the impeller. However, the effect is much more pronounced in part-load compared to overload conditions. In this study, the air–water two-phase flow behavior in a pump inducer was numerically investigated. The main objectives were to clarify the effect of the inducer, the effective operating range, and to examine flow mixing. Several flow conditions were studied, covering part-load, optimal, and overload pumping conditions, together with different relevant gas volume fractions (1%, 3%, and 5%). The simulations were performed using a transient setup and a moving-mesh approach. Two-phase air–water interactions were modeled by the volume of fluid (VOF) method. After checking the proper discretization in space and time, the model was validated against experimental results, revealing excellent agreement. The numerical analysis was able to explain different effects of inducers in part-load and overload conditions. Under overload conditions, the flow separates, leading to the generation of axial vortices and to a negative pressure change across the inducer; additionally, the residence time is reduced, hindering mixing. These vortices are intensified as the gas volume fraction increases, reducing further the pressure downstream of the inducer. This is the reason why inducers can mainly be used in part-load and near optimal conditions in order to improve pumping of two-phase flows.

Visual Criteria for Measuring Two-phase Flow Rate in Venturi with Flow Homogenizer

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Sangho Sohn ◽  
Jaebum Park ◽  
Dong-Wook Oh
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Differential Pressure ◽  
Phase Flow ◽  
Two Phase ◽  
3 Dimensional ◽  
Lower Amplitude ◽  
Gas Volume

A simple use of Venturi might be used to measure two-phase flow rate within relatively low GVF(gas volume fraction). Upstream flow entering Venturi can be improved with installed flow homogenizer which is easily fabricated by 3-dimensional printer with multiple holes. Simultaneous measurement between high-speed flow visualization and dynamic differential pressure measurement was made to find visual criteria for two-phase flow rate measurement with different GVF ranged from 0% to 30%. It was observed that the two-phase flow rate can be reliably measured up to 15% of GVF using flow homogenizer. FFT(Fast-Fourier Transform) results proved that the long flow homogenizers (type 2 and 4) showed a lower amplitude of differential pressure (Δp) than the short flow homogenizers (type 1 and 3) respectively. So the optimized flow homogenizer can be useful to measure two-phase flow rate at low GVF.

scholarly journals Experimental Investigations on the Inner Flow Behavior of Centrifugal Pumps under Inlet Air-Water Two-Phase Conditions

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4377 ◽  
Author(s):  
Si ◽  
Zhang ◽  
Bois ◽  
Zhang ◽  
Cui ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Performance Degradation ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Impeller Blade ◽  
Pump Performance ◽  
Starting Point

Centrifugal pumps are widely used and are known to be sensitive to inlet air-water two-phase flow conditions. The pump performance degradation mainly depends on the changes in the two-phase flow behavior inside the pump. In the present paper, experimental overall pump performance tests were performed for two different rotational speeds and several inlet air void fractions (αi) up to pump shut-off condition. Visualizations were also performed on the flow patterns of a whole impeller passage and the volute tongue area to physically understand pump performance degradation. The results showed that liquid flow modification does not follow head modification as described by affinity laws, which are only valid for homogeneous bubbly flow regimes. Three-dimensional effects were more pronounced when inlet void fraction increased up to 3%. Bubbly flow with low mean velocities were observed close to the volute tongue for all αi, and returned back to the impeller blade passages. The starting point of pump break down was related to a strong inward reverse flow that occurred in the vicinity of the shroud gap between the impeller and volute tongue area.

Numerical Simulation of the Two-Phase Flow in Novel Combined Top and Corner Spray Degassing Tank for Aluminum Melt

2012 ◽  
Vol 510 ◽  
pp. 790-794
Author(s):  
Hui Sun ◽  
Zhi Yong Zhou
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Fluid Model ◽  
Flow Behavior ◽  
Phase Flow ◽  
Gas Velocity ◽  
Two Phase ◽  
Aluminum Melt ◽  
Two Fluid Model ◽  
Gas Liquid Flow

The Eulerian two-fluid model incorporated with the multiple reference frame approach is adopted to predict the gas-liquid two-phase flow in the novel combined top and corner spray degassing tank for aluminum melt. The influence of different parameters, such as gas velocity or hole areas at the tank corners on the gas-liquid flow behavior is also investigated. Results show that little gas emerges near the wall of tank equipped with traditional rotating spray degasser. Using the combined top and corner spray degasser, the distribution of bubbles in the tank, especially near the tank wall, is improved significantly, which advantages the hydrogen removal. With the increasing gas velocity or hole areas at the tank corners, the width of ring zone with low gas volume fraction decreases, and thus enhances the effect of hydrogen removal.

Experimental investigation on the performance of a side channel pump under gas–liquid two-phase flow operating condition

2017 ◽  
Vol 231 (7) ◽  
pp. 645-653 ◽  
Author(s):  
Fan Zhang ◽  
Martin Böhle ◽  
Shouqi Yuan
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Low Flow ◽  
Side Channel ◽  
Phase Flow ◽  
Vane Pump ◽  
Two Phase ◽  
Operating Condition ◽  
Gas Volume Fraction ◽  
Gas Volume

Side channel pump is a kind of small volume vane pump with low flow rate but high head and most side channel pumps can transport gas–liquid two-phase flow. In order to investigate the performance of this type of pump depending on the blade suction angle under gas–liquid two-phase flow operating condition, an experimental study has been carried out. The head and efficiency curves, and the influence of blade suction angle changes on these curves for different inlet gas volume fraction states are analyzed in detail. Moreover, the gas transporting capability of the impeller with three different blade suction angles (10°, 20°, 30°) are also compared. The results show that the head and efficiency performances of the three impellers decrease a large value when the side channel pump operates with a little gas inside, and the operating range narrows as well. With the increasing of inlet gas volume fraction, the performance of the side channel pump worsens. The head and efficiency performances in the single-phase state improve by increasing the blade suction angle, but decrease by increasing the blade suction angle in the gas–liquid two-phase flow state. The maximum gas transporting capability of the impeller with a small blade suction angle is better than a large blade suction angle. Analysis on the measured data allows a better understanding of the effect of inlet gas quantity on the performance of the side channel pump with different blade suction angles, and it could supply the design reference for two-phase flow side channel pumps.

Investigation of the Self-Priming Process of Self-Priming Pump Under Gas-Liquid Two-Phase Condition

2014 ◽  
Author(s):  
Guidong Li ◽  
Yang Wang ◽  
Gang Yin ◽  
Yurui Cui ◽  
Qihong Liang
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Guide Vane ◽  
The Self ◽  
Phase Flow ◽  
Two Phase ◽  
Pump Chamber ◽  
Priming Process ◽  
Gas Volume Fraction ◽  
Gas Volume

The self-priming process of self-priming pump is gas-liquid two-phase flow process with complex internal transient flow. The effect of gas-liquid mixing and separating performances will play a crucial role during self-priming process. In order to study the self-priming process and improve the self-priming performance, the model named JETST-100 was selected. Based on Eulerian-Eulerian multiphase flow model, transient numerical simulation of the gas-liquid mixing and separating phenomena on the pump chamber was carried out by using CFX software. The distributions of velocity vector, contours of gas volume fraction and liquid velocity of the pump or jet aerator, and the change of the gas volume fraction by monitoring points on the jet aerator were obtained. Test and simulation results show that the gas-liquid two-phase flow from the guide vane will form a larger velocity circulation, so that the gas-liquid separation is not sufficient. And the volume fraction of liquid inside pump chamber decrease with a large amount of water enters the outlet pipe. It is found that adding the baffle plate can prevent the generation of circulation on guide vane back, the gas-phase volume fraction of jet aerator inlet and nozzle outlet decreases, improve the self-priming performance of the pump.

Numerical Simulation on Filling Process of SiCp/A357 Composites

2017 ◽  
Vol 898 ◽  
pp. 859-864
Author(s):  
Hao Zhang ◽  
Zhi Feng Zhang ◽  
Zhen Lin Zhang ◽  
Yue Long Bai ◽  
Jun Xu
Keyword(s):  
High Efficiency ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Casting Process ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Process ◽  
A357 Alloy ◽  
Al Composite

With high module, high strength and good isotropy, SiCp/Al composite has been widely applied in the fields such as airspace, transportation vehicle and electronic packaging. Stir casting process with advantages of low cost, high efficiency and near-net shape has become a main production method, but the two-phase flow behavior of the SiCp/Al composite during casting process has greatly effect on particle distribution and ultimate properties of casting. In this work, a two-phase flow computational model was developed, and the filling flow process of SiCp/A357 composite based on a benchmark test die was numerically simulated with commercial software Fluent. The effects of SiCp volume fraction and SiCp size on the flow field of SiCp/A357 composite were investigated. The results showed that there existed difference of flow fields between A357 alloy and SiCp/A357 composite, and the simulation results would be helpful to optimize the casting process.

Hydrodynamic Design of Rotodynamic Pump Impeller for Multiphase Pumping by Combined Approach of Inverse Design and CFD Analysis

2004 ◽  
Vol 127 (2) ◽  
pp. 330-338 ◽  
Author(s):  
Shuliang Cao ◽  
Guoyi Peng ◽  
Zhiyi Yu
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Flow Analysis ◽  
Phase Flow ◽  
Combined Approach ◽  
Two Phase ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Gas Volume Fraction ◽  
Gas Volume

A combined approach of inverse method and direct flow analysis is presented for the hydrodynamic design of gas-liquid two-phase flow rotodynamic pump impeller. The geometry of impeller blades is designed for a specified velocity torque distribution by treating the two-phase mixture as a homogeneous fluid under the design condition. The three-dimensional flow in the designed impeller is verified by direct turbulent flow analysis, and the design specification is further modified to optimize the flow distribution. A helical axial pump of high specific speed has been developed. To obtain a favorable pressure distribution the impeller blade was back-loaded at the hub side compared to the tip side. Experimental results demonstrate that the designed pump works in a wide flow rate range until the gas volume fraction increases to over 50% and its optimum hydraulic efficiency reaches to 44.0% when the gas volume fraction of two-phase flow is about 15.6%. The validity of design computation has been proved.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

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