The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Wenwu Zhang - One of the best experts on this subject based on the ideXlab platform.
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analysis of phase interaction and gas holdup in a multistage multiphase Rotodynamic Pump based on a modified euler two fluid model
Renewable Energy, 2021Co-Authors: Wenwu Zhang, Xing Xie, Baoshan ZhuAbstract:Abstract Due to the effect of unit stages, the gas-liquid flow and the interphase forces in the multistage multiphase Pump are more disordered, which will affect the energy conversion efficiency. However, the characteristics of phase interaction and gas holdup in such a Pump are not clear. In this study, based on a modified Euler two-fluid model, simulations of a multiphase Rotodynamic Pump with two stages were carried out with medium combinations of air-water and air-crude. The characteristics of phase interaction and gas holdup were analyzed at different inlet gas void fractions (IGVFs), and inlet bubble diameters. The results show that the overall changing trend of interphase forces is the same between the first and second stages at different IGVFs, but the magnitudes of interphase forces in the second stage are slightly smaller, especially for the medium combination of air-water. Moreover, the drag is more sensitive to the IGVF, while the lift and added mass force are more sensitive to the medium viscosity. As the increase of the inlet bubble diameter, the difference of the gas holdup effect in the Pump increases gradually at IGVF = 9.0%, and the maximum almost occurs in the first stage guide vane (S1). When the bubble diameter increases to 0.7 mm, the degree of gas accumulation and gas-liquid velocity difference increase significantly, resulting in a significant increase of the disordered degree of lift and added mass force.
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application of a non uniform bubble model in a multiphase Rotodynamic Pump
Journal of Petroleum Science and Engineering, 2019Co-Authors: Wenwu ZhangAbstract:Abstract Thus far, the break-up and the coalescence of bubbles have never been considered in the simulations of the multiphase Pumps, while the non-uniform bubble model (NUBM) considered in this study has been successfully applied to predict the external characteristics, phase interaction and internal flow characteristics of a multiphase Rotodynamic Pump. On the basis of the Euler two-fluid model, the drag model considered to be the most important phase interaction model was modified using the secondary development technology of ANSYS CFX 16.0. The correctness of the modified drag model and that of the applied NUBM were verified by comparing with the experimental data at different inlet gas void fractions (IGVFs). When the IGVF was 21%, the relative errors of the Pump heads with CD_0.34, CD_SN, and CD_modified were 10.30%, 8.19% and 1.43%, respectively. Meanwhile, the comparative results with and without NUBM showed a small difference in the corresponding interphase forces (drag, added mass force, and lift) under the relatively small IGVF condition (IGVF = 3%), while the difference became obvious under a large IGVF condition (IGVF = 15%).
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numerical analysis of pressure fluctuation in a multiphase Rotodynamic Pump with air water two phase flow
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2019Co-Authors: Wenwu Zhang, Jianxin YangAbstract:Pressure fluctuation in single-phase Pumps has been studied widely, while less attention has been paid to research on multiphase Pumps that are commonly used in the petroleum chemical industry. Therefore, this study investigates the pressure fluctuation for a multiphase Rotodynamic Pump handling air–water two-phase flow. Simulations based on the Euler two-fluid model were carried out using ANSYS_CFX16.0 at different Inlet Gas Void Fractions ( IGVF s) and various flow rate values. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the accuracy of the numerical method was tested by comparing the experimental data. The results showed that the rotor–stator interaction was still the main generation driver of pressure fluctuation in gas–liquid two-phase Pumps. However, the fluctuation near the impeller outlet ascribe to the rotor–stator interaction was weakened by the complex gas–liquid flow. For the different IGVF , the variation trend of fluctuation was similar along the streamwise direction. That is, the fluctuation in the impeller increased before decreasing, while in the guide vane it decreased gradually. Also, the fluctuation in the guide vane was generally greater than for the impeller and the maximum amplitude appeared in the vicinity of guide vane inlet.
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study of the gas distribution in a multiphase Rotodynamic Pump based on interphase force analysis
Energies, 2018Co-Authors: Wenwu Zhang, Muhammad Noaman Zahid, Zhiyi Yu, Yongjiang LiAbstract:The performance of multiphase Pumps has a remarkable influence on the related industrial application. In order to understand the flow field and gas-liquid phase interaction characteristics of a multiphase Rotodynamic Pump, detailed numerical analysis of the Pump with a medium of air-water combination was carried out for the whole flow passage by means of a structured mesh using ICEM_CFD and TurboGrid. The results for 21% inlet gas void fraction (IGVF = 21%) condition showed that the magnitude ratio of non-drag forces to drag in impeller and guide vane passages was generally less than 1, whereas it was always less than 0.2 for the magnitude ratio of turbulent dispersion force to drag. When the IGVF was increased, the variation range of interphase forces in the impeller was greater than that in the guide vane. In addition, the gas in the impeller mainly accumulated near the suction surface in the outlet region. Further, with increased IGVF, the degree of aggregation increased as well as the gas inhomogeneity, and consequently the interphase forces in the impeller increased. Due to the divergent structure of the guide vane, obvious vortexes emerged at the hub and gradually moved toward the blade pressure surface along the streamwise direction.
Yongjiang Li - One of the best experts on this subject based on the ideXlab platform.
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study of the gas distribution in a multiphase Rotodynamic Pump based on interphase force analysis
Energies, 2018Co-Authors: Wenwu Zhang, Muhammad Noaman Zahid, Zhiyi Yu, Yongjiang LiAbstract:The performance of multiphase Pumps has a remarkable influence on the related industrial application. In order to understand the flow field and gas-liquid phase interaction characteristics of a multiphase Rotodynamic Pump, detailed numerical analysis of the Pump with a medium of air-water combination was carried out for the whole flow passage by means of a structured mesh using ICEM_CFD and TurboGrid. The results for 21% inlet gas void fraction (IGVF = 21%) condition showed that the magnitude ratio of non-drag forces to drag in impeller and guide vane passages was generally less than 1, whereas it was always less than 0.2 for the magnitude ratio of turbulent dispersion force to drag. When the IGVF was increased, the variation range of interphase forces in the impeller was greater than that in the guide vane. In addition, the gas in the impeller mainly accumulated near the suction surface in the outlet region. Further, with increased IGVF, the degree of aggregation increased as well as the gas inhomogeneity, and consequently the interphase forces in the impeller increased. Due to the divergent structure of the guide vane, obvious vortexes emerged at the hub and gradually moved toward the blade pressure surface along the streamwise direction.
Zhiyi Yu - One of the best experts on this subject based on the ideXlab platform.
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study of the gas distribution in a multiphase Rotodynamic Pump based on interphase force analysis
Energies, 2018Co-Authors: Wenwu Zhang, Muhammad Noaman Zahid, Zhiyi Yu, Yongjiang LiAbstract:The performance of multiphase Pumps has a remarkable influence on the related industrial application. In order to understand the flow field and gas-liquid phase interaction characteristics of a multiphase Rotodynamic Pump, detailed numerical analysis of the Pump with a medium of air-water combination was carried out for the whole flow passage by means of a structured mesh using ICEM_CFD and TurboGrid. The results for 21% inlet gas void fraction (IGVF = 21%) condition showed that the magnitude ratio of non-drag forces to drag in impeller and guide vane passages was generally less than 1, whereas it was always less than 0.2 for the magnitude ratio of turbulent dispersion force to drag. When the IGVF was increased, the variation range of interphase forces in the impeller was greater than that in the guide vane. In addition, the gas in the impeller mainly accumulated near the suction surface in the outlet region. Further, with increased IGVF, the degree of aggregation increased as well as the gas inhomogeneity, and consequently the interphase forces in the impeller increased. Due to the divergent structure of the guide vane, obvious vortexes emerged at the hub and gradually moved toward the blade pressure surface along the streamwise direction.
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interphase force analysis for air water bubbly flow in a multiphase Rotodynamic Pump
Engineering Computations, 2015Co-Authors: Zhiyi YuAbstract:Purpose – Interphase forces between the gas and liquid phases determine many phenomena in bubbly flow. For the interphase forces in a multiphase Rotodynamic Pump, the magnitude analysis was carried out within the framework of two-fluid model. The purpose of this paper is to clarify the relative importance of various interphase forces on the mixed transport process, and the findings herein will be a base for the future study on the mechanism of the gas blockage phenomenon, which is the most challenging issue for such Pumps. Design/methodology/approach – Four types of interphase forces, i.e. drag force, lift force, virtual mass force and turbulent dispersion force (TDF) were taken into account. By comparing with the experiment in the respect of the head performance, the effectiveness of the numerical model was validated. In conditions of different inlet gas void fractions, bubble diameters and rotational speeds, the magnitude analyses were made for the interphase forces. Findings – The results demonstrate t...
Baoshan Zhu - One of the best experts on this subject based on the ideXlab platform.
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analysis of phase interaction and gas holdup in a multistage multiphase Rotodynamic Pump based on a modified euler two fluid model
Renewable Energy, 2021Co-Authors: Wenwu Zhang, Xing Xie, Baoshan ZhuAbstract:Abstract Due to the effect of unit stages, the gas-liquid flow and the interphase forces in the multistage multiphase Pump are more disordered, which will affect the energy conversion efficiency. However, the characteristics of phase interaction and gas holdup in such a Pump are not clear. In this study, based on a modified Euler two-fluid model, simulations of a multiphase Rotodynamic Pump with two stages were carried out with medium combinations of air-water and air-crude. The characteristics of phase interaction and gas holdup were analyzed at different inlet gas void fractions (IGVFs), and inlet bubble diameters. The results show that the overall changing trend of interphase forces is the same between the first and second stages at different IGVFs, but the magnitudes of interphase forces in the second stage are slightly smaller, especially for the medium combination of air-water. Moreover, the drag is more sensitive to the IGVF, while the lift and added mass force are more sensitive to the medium viscosity. As the increase of the inlet bubble diameter, the difference of the gas holdup effect in the Pump increases gradually at IGVF = 9.0%, and the maximum almost occurs in the first stage guide vane (S1). When the bubble diameter increases to 0.7 mm, the degree of gas accumulation and gas-liquid velocity difference increase significantly, resulting in a significant increase of the disordered degree of lift and added mass force.
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Effect of Virtual Mass Force on the Mixed Transport Process in a Multiphase Rotodynamic Pump
Advances in Mechanical Engineering, 2014Co-Authors: Baoshan Zhu, Shuliang Cao, Ying LiuAbstract:To explore the effect of virtual mass force, the unsteady two-phase flow in a multiphase Rotodynamic Pump impeller was numerically simulated, where the inlet gas void fraction was 4.9%, 14.9%, and 25.2%, respectively. The drag force and the virtual mass force were accounted for and the cases with and without the latter one were both analyzed for comparison. The results show that the trajectories of the gas bubbles are influenced by the virtual mass force evidently in the inlet extended region. Due to the effect of virtual mass force, some gas will firstly move to the shroud before accumulating in the hub region of the impeller. The characteristic of the Pump head was discussed and the results demonstrate that the virtual mass force can decrease the Pump head and lead to its fluctuation. In addition, the comparison between the steady and unsteady simulation shows that the virtual mass effect can be found only by unsteady simulation.
Muhammad Noaman Zahid - One of the best experts on this subject based on the ideXlab platform.
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study of the gas distribution in a multiphase Rotodynamic Pump based on interphase force analysis
Energies, 2018Co-Authors: Wenwu Zhang, Muhammad Noaman Zahid, Zhiyi Yu, Yongjiang LiAbstract:The performance of multiphase Pumps has a remarkable influence on the related industrial application. In order to understand the flow field and gas-liquid phase interaction characteristics of a multiphase Rotodynamic Pump, detailed numerical analysis of the Pump with a medium of air-water combination was carried out for the whole flow passage by means of a structured mesh using ICEM_CFD and TurboGrid. The results for 21% inlet gas void fraction (IGVF = 21%) condition showed that the magnitude ratio of non-drag forces to drag in impeller and guide vane passages was generally less than 1, whereas it was always less than 0.2 for the magnitude ratio of turbulent dispersion force to drag. When the IGVF was increased, the variation range of interphase forces in the impeller was greater than that in the guide vane. In addition, the gas in the impeller mainly accumulated near the suction surface in the outlet region. Further, with increased IGVF, the degree of aggregation increased as well as the gas inhomogeneity, and consequently the interphase forces in the impeller increased. Due to the divergent structure of the guide vane, obvious vortexes emerged at the hub and gradually moved toward the blade pressure surface along the streamwise direction.
