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Wenwu Zhang - One of the best experts on this subject based on the ideXlab platform.
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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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numerical study of Pressure Fluctuation in a gas liquid two phase mixed flow pump
Energies, 2017Co-Authors: Wenwu Zhang, Baoshan ZhuAbstract:To explore the Pressure Fluctuation characteristics in a mixed-flow pump handling a gas-liquid two-phase flow, an unsteady simulation was carried out with ANSYS CFX for the whole flow passage when the inlet gas void fraction (IGVF) was 0%, 5%, and 10%, respectively. Under pure water conditions (IGVF = 0%), the reliability of the simulation was verified by comparing with the experiment in both aspects of external characteristics and Fluctuation. Through the implementation of the fast Fourier transform (FFT) algorithm, the characteristics of the Pressure Fluctuation in the impeller and the guide vane were obtained at different IGVF conditions. The results demonstrate that Pressure Fluctuations exist under different IGVF conditions due to the rotor-stator interaction and the gas-liquid phase interaction, and the intensity of the Fluctuation is firstly enhanced, and then weakened, along the streamwise direction with the maximum located near the impeller outlet. The relationship between the gas content and the Pressure Fluctuation was analyzed, and it is shown that the regional Pressure Fluctuation will be intensified only if the gas content therein reaches a certain level and the local phase interaction is strong. In addition, the Pressure Fluctuation in both the rotor-stator interaction region and the guide vane may be effectively inhibited under small IGVF conditions.
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Influence of Tip Clearance on Pressure Fluctuation in Low Specific Speed Mixed-Flow Pump Passage
Energies, 2017Co-Authors: Wenwu Zhang, Zhiyi YuAbstract:To explore the influence of tip clearance on Pressure Fluctuation in a low specific speed mixed-flow pump, tip clearances δ of 0.25 mm, 0.75 mm and 1.00 mm, along with no tip clearance, were selected. The reliability of the simulation was verified by comparison with the experimental data of external characteristics and Fluctuation in the guide vane passage. Through ANSYS-CFX, MATLAB code and fast Fourier transform (FFT) algorithm, Pressure Fluctuation characteristics in this pump were obtained. The results show that Pressure Fluctuation exists in all conditions due to the rotor-stator interaction. Under the no tip clearance and tip clearance conditions, the maximum Fluctuation value was located near the guide inlet and impeller outlet, respectively. Clearance leakage had less influence on Pressure Fluctuation at the impeller inlet and central regions within a certain range of the clearance; beyond this range, Fluctuations in the whole flow passage increased significantly, while the clearance variation had less effect on Fluctuation in the guide vane. When the tip clearance value was 1.00 mm, Pressure Fluctuation of the shroud at the impeller inlet section suddenly increases, which was closely related to the obvious leakage vortexes and a larger low Pressure area.
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characteristic analysis on the Pressure Fluctuation in the impeller of a low specific speed mixed flow pump
Microelectronics Systems Education, 2016Co-Authors: Wenwu Zhang, Baoshan ZhuAbstract:To explore the Pressure Fluctuation characteristics of a low speed specific speed mixed flow pump caused by rotor-stator interaction, the unsteady flow was simulated with CFX for the whole flow passage of a mixed flow pump with a specific speed of 148.8. The structured mesh of the computation domain was generated with ICEM CFD and TurboGrid, and mesh-independent analysis was done in the design condition. Through the comparison with the experiment data, the reliability of the simulation was verified. In different locations of the impeller passage, monitoring points were set. With Fast Fourier Transform (FFT), the characteristic analysis on the Pressure Fluctuation in the impeller passage was done for three flow rate conditions (0.75Qd, Qd, 1.25Qd). The results show that the Pressure Fluctuation amplitude increases from the inlet to the outlet. And the maximum values in different flow rates exist near the hub of the outlet; The Pressure Fluctuation is small in the design condition, but the largest in the small flow rate condition, accompanied by the secondary dominant frequencies with large amplitudes; In the small flow rate condition and design condition, the dominant frequency varies from the inlet to the outlet because the combine action of the impeller and guide vane; while in the large flow rate condition, the Pressure Fluctuation in the whole impeller passage is affected significantly by the guide vane, and the domain frequency is 8 times the rotational frequency of impeller. In addition, the change of Pressure Fluctuation from the Pressure surface to the suction surface in the off-design conditions is investigated, and the results demonstrates that the intensity of the Pressure Fluctuation in the impeller passage is closely related with the impeller as well as the distribution of the vorticity and the Pressure.
Zhiyi Yu - One of the best experts on this subject based on the ideXlab platform.
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influence of impeller staggered arrangement on radial force and Pressure Fluctuation for a double suction centrifugal pump
Advances in Mechanical Engineering, 2018Co-Authors: Yu Song, Zhiyi YuAbstract:Influence of impeller arrangement on performance, radial force, and Pressure Fluctuation for a double-suction centrifugal pump is investigated. In comparison of the original impeller with staggered...
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Influence of Tip Clearance on Pressure Fluctuation in Low Specific Speed Mixed-Flow Pump Passage
Energies, 2017Co-Authors: Wenwu Zhang, Zhiyi YuAbstract:To explore the influence of tip clearance on Pressure Fluctuation in a low specific speed mixed-flow pump, tip clearances δ of 0.25 mm, 0.75 mm and 1.00 mm, along with no tip clearance, were selected. The reliability of the simulation was verified by comparison with the experimental data of external characteristics and Fluctuation in the guide vane passage. Through ANSYS-CFX, MATLAB code and fast Fourier transform (FFT) algorithm, Pressure Fluctuation characteristics in this pump were obtained. The results show that Pressure Fluctuation exists in all conditions due to the rotor-stator interaction. Under the no tip clearance and tip clearance conditions, the maximum Fluctuation value was located near the guide inlet and impeller outlet, respectively. Clearance leakage had less influence on Pressure Fluctuation at the impeller inlet and central regions within a certain range of the clearance; beyond this range, Fluctuations in the whole flow passage increased significantly, while the clearance variation had less effect on Fluctuation in the guide vane. When the tip clearance value was 1.00 mm, Pressure Fluctuation of the shroud at the impeller inlet section suddenly increases, which was closely related to the obvious leakage vortexes and a larger low Pressure area.
Baoshan Zhu - One of the best experts on this subject based on the ideXlab platform.
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numerical study of Pressure Fluctuation in a gas liquid two phase mixed flow pump
Energies, 2017Co-Authors: Wenwu Zhang, Baoshan ZhuAbstract:To explore the Pressure Fluctuation characteristics in a mixed-flow pump handling a gas-liquid two-phase flow, an unsteady simulation was carried out with ANSYS CFX for the whole flow passage when the inlet gas void fraction (IGVF) was 0%, 5%, and 10%, respectively. Under pure water conditions (IGVF = 0%), the reliability of the simulation was verified by comparing with the experiment in both aspects of external characteristics and Fluctuation. Through the implementation of the fast Fourier transform (FFT) algorithm, the characteristics of the Pressure Fluctuation in the impeller and the guide vane were obtained at different IGVF conditions. The results demonstrate that Pressure Fluctuations exist under different IGVF conditions due to the rotor-stator interaction and the gas-liquid phase interaction, and the intensity of the Fluctuation is firstly enhanced, and then weakened, along the streamwise direction with the maximum located near the impeller outlet. The relationship between the gas content and the Pressure Fluctuation was analyzed, and it is shown that the regional Pressure Fluctuation will be intensified only if the gas content therein reaches a certain level and the local phase interaction is strong. In addition, the Pressure Fluctuation in both the rotor-stator interaction region and the guide vane may be effectively inhibited under small IGVF conditions.
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characteristic analysis on the Pressure Fluctuation in the impeller of a low specific speed mixed flow pump
Microelectronics Systems Education, 2016Co-Authors: Wenwu Zhang, Baoshan ZhuAbstract:To explore the Pressure Fluctuation characteristics of a low speed specific speed mixed flow pump caused by rotor-stator interaction, the unsteady flow was simulated with CFX for the whole flow passage of a mixed flow pump with a specific speed of 148.8. The structured mesh of the computation domain was generated with ICEM CFD and TurboGrid, and mesh-independent analysis was done in the design condition. Through the comparison with the experiment data, the reliability of the simulation was verified. In different locations of the impeller passage, monitoring points were set. With Fast Fourier Transform (FFT), the characteristic analysis on the Pressure Fluctuation in the impeller passage was done for three flow rate conditions (0.75Qd, Qd, 1.25Qd). The results show that the Pressure Fluctuation amplitude increases from the inlet to the outlet. And the maximum values in different flow rates exist near the hub of the outlet; The Pressure Fluctuation is small in the design condition, but the largest in the small flow rate condition, accompanied by the secondary dominant frequencies with large amplitudes; In the small flow rate condition and design condition, the dominant frequency varies from the inlet to the outlet because the combine action of the impeller and guide vane; while in the large flow rate condition, the Pressure Fluctuation in the whole impeller passage is affected significantly by the guide vane, and the domain frequency is 8 times the rotational frequency of impeller. In addition, the change of Pressure Fluctuation from the Pressure surface to the suction surface in the off-design conditions is investigated, and the results demonstrates that the intensity of the Pressure Fluctuation in the impeller passage is closely related with the impeller as well as the distribution of the vorticity and the Pressure.
Chienchong Chen - One of the best experts on this subject based on the ideXlab platform.
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characterizations of flow regime transitions in a high Pressure bubble column by chaotic time series analysis of Pressure Fluctuation signals
Chemical Engineering Science, 2001Co-Authors: Tsaojen Lin, R C Juang, Chienchong ChenAbstract:Abstract In this study, experiments are carried out for a high-Pressure bubble column with a perforated plate as the distributor under the operating Pressure up to 15 MPa . Gas holdups and Pressure Fluctuation signals are measured. Analyses of standard deviation and chaotic time series on Pressure Fluctuation signals are conducted to determine the transition gas velocities. The results of chaotic measures, such as the largest Lyapunov exponent, metric entropy and the correlation dimension show that there are bands of transition velocities for each operating Pressure. The general trend is that the transition velocities increase as the operating Pressure rises. Similar trends are also found for the transition velocities obtained by the standard deviation. All the transition velocities resulting from the chaotic measures and the standard deviation show good agreements.
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predictions of flow transitions in a bubble column by chaotic time series analysis of Pressure Fluctuation signals
Chemical Engineering Science, 2001Co-Authors: Tsaojen Lin, R C Juang, Y C Chen, Chienchong ChenAbstract:Abstract In this study, predictions of flow transitions of a bubble column are carried out by chaotic time series analysis of Pressure Fluctuation signals. Pressure signals are measured for four different distributor plates with the superficial gas velocity varying from 0 to approximately 0.22 m / s . Methodology of the chaotic time series analysis is presented, including procedures of the time-delayed phase-space reconstruction and calculation of the chaotic invariants. Four chaotic invariants, which include the largest Lyapunov exponent, metric entropy, correlation dimension and mutual information, of all Pressure signals are computed. The critical gas velocities are determined by the sharp increase or decrease of the obtained chaotic invariants at the flow regime transitions. This simple criterion is consistent with the experimental observations. The obtained critical gas velocities by various chaotic measures for the four different distributor plates are quantitatively consistent and are in good agreement with the results by the gas holdup data.
Lei Tan - One of the best experts on this subject based on the ideXlab platform.
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design method of controllable velocity moment and optimization of Pressure Fluctuation suppression for a multiphase pump
Ocean Engineering, 2021Co-Authors: Wenyang Xiao, Lei TanAbstract:Abstract The multiphase pump is the key technology for offshore oil-gas resources exploitation, and great efforts should be made to guarantee its high-efficiency and stable operation. In the present work, a design method of controllable velocity moment in combination of singularity method is proposed for multiphase pump, and the ranges of dimensionless controllable parameters are determined. Under IGVF (inlet gas volume fraction) = 0%, the Pressure rise and efficiency of optimization pump I increase by 11.9 kPa and 3.6% in comparison of baseline pump, respectively, and the maximum amplitude of Pressure Fluctuation in impeller decreases by 23.1%. Under IGVF = 10%, the Pressure rise and efficiency of optimization pump II increase by 7.6 kPa and 4.51% in comparison of baseline pump, respectively, and the average Pressure Fluctuation intensity of impeller decreases by 47.53%. The optimization mechanism is that the rotor-stator interaction and gas-liquid interaction are suppressed in optimization pump with optimal velocity moment distribution.
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tip clearance on Pressure Fluctuation intensity and vortex characteristic of a mixed flow pump as turbine at pump mode
Renewable Energy, 2018Co-Authors: Yabin Liu, Lei TanAbstract:Abstract The present work investigates the Pressure Fluctuation intensity and vortex characteristic of a mixed flow pump as turbine at pump mode with a tip clearance. The tip clearance between the blade tip and shroud can induce tip leakage flow and interact with main flow, which causes the unstable flow structure and complex vortex in the passage. The external characteristics of experimental results and numerical simulations are in agreement. With tip clearance increasing, the head and efficiency of pump decrease by 10.8% and 6.26%, respectively. The distribution of Pressure Fluctuation intensity is presented as a triangular shape under design flow rate. Results show that the tip leakage vortex (TLV) can be divided into four categories, namely, primary TLV, secondary TLV, entangled TLV, and dispersed TLV. The flow rate has a significant influence on the TLV structure and trajectory, and the starting point of the primary TLV shifts to approximately 20% of the blade chord at large flow rate. The relative vorticity transport equation is introduced to analyze the vortex derivation by using the relative vortex stretching, Coriolis force and viscous diffusion.
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energy performance and Pressure Fluctuation of a multiphase pump with different gas volume fractions
Energies, 2018Co-Authors: Jinsong Zhang, Lei TanAbstract:Large petroleum resources in deep sea, and huge market demands for petroleum need advanced petroleum extraction technology. The multiphase pump, which can simultaneously transport oil and gas with considerable efficiency, has been a crucial technology in petroleum extraction. A numerical approach with mesh generation and a Navier-Stokes equation solution is employed to evaluate the effects of gas volume fraction on energy performance and Pressure Fluctuations of a multiphase pump. Good agreement of experimental and calculation results indicates that the numerical approach can accurately simulate the multiphase flow in pumps. The Pressure rise of a pump decreases with the increasing of flow rate, and the pump efficiency decreases with the increasing of GVF (the ratio of the gas volume to the whole volume). Results show that the dominant frequencies of Pressure Fluctuation in the impeller and diffuser are eleven and three times those of the impeller rotational frequency, respectively. Due to the larger density of water and centrifugal forces, the water aggregates to the shroud and the gas gathers to the hub, which renders the distribution of GVF in the pump uneven. A vortex develops at the blade suction side, near the leading edge, induced by the leakage flow, and further affects the Pressure Fluctuation in the impeller. The obvious vortex in the diffuser indicates that the design of the divergence angle of the diffuser is not optimal, which induces flow separation due to large diffusion ratio. A uniform flow pattern in the impeller indicates good hydraulic performance of the pump.
