Two-phase Flow Pump Research Articles

Experimental Study on the Movement Law of Solid-liquid Two-phase Flow in slurry Pump

Abstract The foundation for the research of two-phase flow pumps is the movement law of solid-liquid two-phase flow in the pump. Currently, research in this direction is mostly conducted through numerical simulation technology, while experimental research is less. In this paper, through the development of a transparent two-phase flow pump, a visual pump test platform with a pipe diameter of 150 mm has been built, and a large number of experimental studies have been conducted on the motion laws of solid-liquid two-phase flow in the pump. The motion laws of particles with different particle diameters in the pump under different flow rates and rotational speeds were obtained through high-speed cameras, including particle velocity and trajectory, and particle collision with the wall. Meanwhile, the wear tests on the pump were carried out with a cast steel and medium high concentration sand pump. The test results show that the location where particles collide with the wall surface more frequently is also the location where wear is more severe. Based on the above test research results, the optimization design direction for two-phase flow pumps is proposed.

Numerical simulation and experimental study on gas–liquid two-phase unsteady flow in a centrifugal pump during the transition process

In order to study the transition process of the gas-liquid two-phase flow in the centrifugal pump, the model pump was studied experimentally. At the same time, the Eulerian-Eulerian heterogeneous flow model and the SST k- ω turbulence model were used to simulate the transition process of the gas-liquid two-phase flow in the pump. The two-phase flow transition process in the pump was studied in detail by using the numerical model verified by experimental results. The flow law of the transition process in the pump was revealed. The judgment criterion for the end of the gas-liquid two-phase flow transition process in the pump was determined. The results show that the gas volume fraction at the pump outlet is more accurate than the outlet pressure. After 0.45 s, the gas volume fraction at the pump outlet does not change with time. It can be regarded as the end of the transition process. The average gas volume fraction at each monitoring point increases rapidly with time, then decreases slowly, and finally reaches stability. The average pressure at each monitoring point first drops rapidly, then rises slightly, and finally reaches a stable value. Along the radial direction of the section VIII in the volute, the amplitude of the gas velocity fluctuation gradually decreases, and the gas velocity gradually changes from greater than the liquid velocity to less than the liquid velocity since the driving effect of the impeller becomes weak. This study is of great significance to further improve the structural design of the gas-liquid two-phase flow pump and improve the stability of the pump operation.

Effect of Thickness Ratio Coefficient on the Mixture Transportation Characteristics of Helical–Axial Multiphase Pumps

With the decrease of oil and gas resources on land, increased attention has been paid to multiphase oil–gas exploitation and the transportation technology represented by oil–gas multiphase pumps. The helical–axial multiphase pump has become the focus of research on oil and gas mixed transmission technology due to its relatively high operating efficiency and adaptability to a wide range of gas volume fraction changes. In order to investigate the thickness variation in the air foil from the hub to the shroud of the blade on the mixture transportation characteristics of the gas–liquid two-phase flow in a helical–axial pump, the thickness ratio coefficient ξ was introduced, and the hydraulic performance of the single compression unit with different thickness ratio coefficients was investigated. A single compression unit including an impeller, diffuser, inlet section and outlet section of a helical–axial multiphase pump. The hydraulic performance including the hydraulic head and efficiency was investigated by numerical simulation with the Eulerian multiphase model and the shear stress transport (SST) k-w turbulence model. In order to demonstrate the validity of the numerical simulation approach, the hydraulic head and efficiency of the basic model was measured based on a gas–liquid two-phase flow pump performance test bench. The simulation results agreed well with the experimental results; the error between the simulation results and experimental results of different inlet gas volume fractions was within 10% at the design point, which indicated the numerical simulation method can be used in the research. The thickness ratio coefficient ξ, which was taken as a variable, and the aggregation degree λ of the gas were introduced to analyze the gas–liquid mixture transportation characteristics of the pump. The thickness ratio coefficient was selected in a range from 0.8 to 1.8. The results showed that, for the same hub thickness, the head coefficient and efficiency increase, and the aggregation degree of gas decreases with the decreasing of the thickness ratio coefficient. The head coefficient of the modification multiphase pump was 5.8% higher in comparison to the base pump while the efficiency was 3.1% higher than that of the base pump, the aggregation degree of this model was the lowest, which was 30.3%; the optimal model in the research was the model of scheme 1 with ξ = 0.8. The accumulation of gas in the flow passage of the impeller could be delayed to the trailing edge of the blade by adjusting the thickness ratio coefficient, which produced a super-separated airfoil for helical–axial multiphase pumps and effectively ensured reliable operation under high gas volume fraction conditions. The accumulation area of gas was consistent with the area in which the gradient of turbulent kinetic energy was large.

Investigation on the Handling Ability of Centrifugal Pumps under Air–Water Two-Phase Inflow: Model and Experimental Validation

The paper presents experimental and numerical investigations performed on a single stage, single-suction, horizontal-orientated centrifugal pump in air–water two-phase non-condensable flow conditions. Experimental measurements are performed in a centrifugal pump using pressure sensor devices in order to measure the wall static pressures at the inlet and outlet pump sections for different flow rates and rotational speeds combined with several air void fraction (a) values. Two different approaches are used in order to predict the pump performance degradations and perform comparisons with experiments for two-phase flow conditions: a one-dimensional two-phase bubbly flow model, and a full “Three-Dimensional Unsteady Reynolds Average Navier–Stokes” (3D-URANS) simulation using a modified k-epsilon turbulence model combined with the Euler–Euler inhomogeneous two-phase flow description. The overall and local flow features are presented and analyzed. Limitations concerning both approaches are pointed out according to some flow physical assumptions and measurement accuracies. Some additional suggestions are proposed in order to improve two-phase flow pump suction capabilities.

Experimental study and numerical simulation of the solid-phase particles' influence on outside characteristics of slurry pump

At present solid-liquid two-phase flow pump faces two big problems: the low efficiency, the short life, then the concentration of the conveyed solid-phase media are the important factors which affect the outside characteristics about this two phase flow pump. This article presents the outside characteristics' experimental research and internal flow field's simulation analysis on AH type slurry pump which is product by Shijiazhuang Shi- Jiang pump industry, discusses the flow rule in the impeller, and summaries the influence of the solid phased particles' concentration on the performance of the slurry pump's outside characteristics. At last, the rationality and accuracy of the numerical calculation method are verified through the way of comparing numerical simulation with experimental results in this two phase flow pump. And the relation between slurry pump's outside characteristics and granule concentration is summarized, which provided theoretical guidance for the slurry pump's optimization design and selection.

Study of Liquid-Solid Two Phase Flow in the Volute of Centrifugal Pump

Particle Image Velocimetry combined with image processing program is used to measure the salt-out two phase flow in the volute. The velocity distribution of different phases are obtained respectively under different temperatures. The experimental results indicate that :As the increasing of discharge, the liquid velocity becomes larger; In the same radial direction, the velocity decrease as the increase of radial; As the temperature decrease , the particles become larger, and the particle velocity become smaller. Through analyzing the results, some characteristics of this kind flow in volute are obtained and some guiding advices are presented to designing the volute of two-phase flow pump.

Study of a Two-Phase Flow Pump and Separator System

The Aero-Thermo-Mechanics (ATM) Department of ULB (Université Libre de Bruxelles) is developing an original system to pump and separate a two-phase flow. Many applications need to extract a certain phase of a multiphase flow: oil extraction, flow in nuclear pumps, flow in aircraft lubrication systems, pulp and paper processing, etc. The main objective of this study is to obtain a lightweight, compact, and efficient system that can both extract the gas of a two-phase flow and increase the pressure of the liquid phase. Prototypes with different designs were first tested at ULB on a specific test bench using water and air. The current prototype is a kind of axial-centrifugal pump. The axial part is used to separate the two phases of the flow and to collect, in the centrifugal part, the liquid phase only. The test results of the water-air prototypes have allowed to identify the key design and working parameters for efficient separation and pumping. A theoretical model has also been developed to describe the behavior of these prototypes. After successful tests with water-air mixtures, the technology has been implemented for a hot oil-air mixture. The tests with oil-air mixtures are performed on the aeroengine lubrication system test bench that the ATM Department developed and continues developing for other projects. At the same time, the flow field in the pump and separator system is being studied with commercial computational fluid dynamics software packages. Several two-phase flow models are considered for this particular application.

Study on Design of Air-water Two-phase Flow Centrifugal Pump Based on Similarity Law

A conventional centrifugal pump causes a drastic deterioration of air-water two-phase flow performances even at an air-water two-phase flow condition of inlet void fraction less than 10% in the range of relatively low water flow rate. Then we have developed a two-phase flow centrifugal pump which consists of a tandem arrangement of double rotating cascades and blades of outer cascade have higher outlet angle more than <TEX>$90^{\circ}$</TEX>. In design of the two-phase flow pump for various sized and operating conditions, similarity relations of geometric dimensions to hydraulic performances is very useful. The similarity relations of rotational speed, impeller diameter and blade height are investigated for the developed impeller in the present paper. As the results, the similarity law of rotational speed and impeller diameter is clarified experimentally even in two-phase flow condition. In addition, influences of blade height on air-water two-phase flow performances indicate a little difference from the similarity relations.

Experiments on Air-Water Two-Phase Flow Pump Impeller with Rotating-Stationary Circular Cascades and Recirculating Flow Holes.

Gas accumulation and its extension in a centrifugal impeller of a two-phase flow pump cause head degradation. In order to decrease the head degradation, a special type of impeller has been designed based on the following concepts. The open impeller consists of two stages of rotating and stationary circular cascades with an appropriate number of thin blades for creating a dispersive effect of each cascade inlet for gas-phase flow. The outer rotating cascade has a large blade outlet angle to keep the pump head high even at high void fraction. Holes on the rotating disk, through which recirculating liquid flows may blow off the gas accumulation region, are equipped in each flow passage. The newly conceptualized impeller was examined experimentally. Results are discussed in the present paper with help of visual observation of gas behavior in the impeller flow passage.

Some Experiments on an Air-Water Two-Phase Flow Pump Impeller with Rotating-Stationary Circular Cascades and Recirculating Flow Holes.

Gas accumulation and its elongation in a centrifugal impeller of liquid/gas two-phase flow pump cause head degradation. In order to decrease the head degradation, a special type of open impeller has been designed on the basis of the following concepts. A designed impeller consists of two stages of rotating and stationary circular cascades to create a dispersive effect of each cascade inlet for gas-phase flow. The outer rotating cascade has a large blade outlet angle to keep the pump head high even at high void fraction. Holes made through the rotating disk, through which recirculating liquid flows may blow off the gas accumulating region, are equipped in each flow passage. This newly conceptualized impeller was examined experimentally. Results are discussed in the present paper on how to improve the two-phase flow performance.

Gas-Liquid Two-Phase Flow Performance of Turbo-Pumps

A gas-liquid two-phase flow problem in turbo-pumps has lately become of interest to pump designers and engineers. The final goal in tackling this problem is to develop a pump which does not lose its pumping function even in a two-phase flow with high void fraction. In this report the transition from a bubbly flow to gas accumulation in the centrifugal pump impeller with inlet void fraction increasing is discussed after showing qualitatively that the gas accumlation in the impeller causes the pump head degradation. Next, effects of pump geometries on the head degradation are made clear from the review of past experimental results. Finally, a conceptual view for designing this kind of pump is described in the present situation of two-phase flow pump research.

Gas-Liquid Two-Phase Flow Performance of Turbo-Pumps

A gas-liquid two-phase flow problem in turbo-pumps has lately become of interest to pump designers and engineers. The final goal in tackling this problem is to develop a pump which does not lose its pumping function even in a two-phase flow with high void fraction. In this report the transition from a bubbly flow to gas accumulation in the centrifugal pump impeller with inlet void fraction increasing is discussed after showing qualitatively that the gas accumlation in the impeller causes the pump head degradation. Next, effects of pump geometries on the head degradation are made clear from the review of past experimental results. Finally, a conceptual view for designing this kind of pump is described in the present situation of two-phase flow pump research.

Three-dimensional calculation of air-water two-phase flow in centrifugal pump impeller based on a bubbly flow model. (2nd report. Prediction of pump performance).

This paper is concerned with the determination of the performance change in pumps operating under two-phase flow conditions based on the calculated distributions of velocities and void fraction, in which the mixture is assumed to be an inviscid bubbly flow with the slippage between two phases. The estimated changes in the theoretical head are confirmed with experiments within the range of the bubbly flow regime. The calculated head due to the momentum exchanges between two phases is also favorably compared with the measured value of the head loss within the same range, when the hydraulic loss due to wall friction is assumed to be zero under two-phase flow conditions. The head-loss ratio obtained shows nearly the same value as the experiments, showing this analytical model to be applicable to the prediction of the two-phase flow pump performance.