Effect of the inlet gas void fraction on the tip leakage vortex in a multiphase pump

Shi, Guangtai; Liu, Zongku; Xiao, Yexiang; Yang, Hong; Li, Helin; Liu, Xiaobing

doi:10.1016/j.renene.2019.12.117

Cited by 30 publications

(17 citation statements)

References 21 publications

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“…The discretization of the control equation is based on the finite volume method, and a control volume composed of internal unit nodes was considered. The SST k-ω model was chosen as the turbulence model to capture the separated flow near the tip clearance more accurately [22]. Compared with the standard k-ε and RNG k-ε models, this model considers the viscosity of the inner wall of the model and has better turbulent shear stress transmission.…”

Section: Methodsmentioning

confidence: 99%

Effect of Tip Clearance Size on Tubular Turbine Leakage Characteristics

Zhu

2021

Processes

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To study the effect of tip clearance on unsteady flow in a tubular turbine, a full-channel numerical calculation was carried out based on the SST k–ω turbulence model using a power-plant prototype as the research object. Tip leakage flow characteristics of three clearance δ schemes were compared. The results show that the clearance value is directly proportional to the axial velocity, momentum, and flow sum of the leakage flow but inversely proportional to turbulent kinetic energy. At approximately 35–50% of the flow direction, velocity and turbulent kinetic energy of the leakage flow show the trough and peak variation law, respectively. The leakage vortex includes a primary tip leakage vortex (PTLV) and a secondary tip leakage vortex (STLV). Increasing clearance increases the vortex strength of both parts, as the STLV vortex core overlaps Core A of PTLV, and Core B of PTLV becomes the main part of the tip leakage vortex. A “right angle effect” causes flow separation on the pressure side of the tip, and a local low-pressure area subsequently generates a separation vortex. Increasing the gap strengthens the separation vortex, intensifying the flow instability. Tip clearance should therefore be maximally reduced in tubular turbines, barring other considerations.

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Section: Methodsmentioning

confidence: 99%

Effect of Tip Clearance Size on Tubular Turbine Leakage Characteristics

Zhu

2021

Processes

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“…A six-stage spiral axial flow type multiphase pump developed by the authors is selected as the research object in the present study. The pump has a vane type structure and has the advantages of simple structure, small volume, large flow rate and it can be used for transporting fluid with a small number of particles compared with the positive displacement pump [2,33]. The main design parameters are as follows: design flow rate Q = 110 m 3 /h, rotational speed n = 3000 rpm, impeller blades and diffuser blades are 4 and 9, respectively.…”

Section: Research Objectmentioning

confidence: 99%

“…Deep-sea oil and gas resources are usually a mixture of oil, gas, and water, which is a kind of multiphase fluid in truth. The multiphase pump is one of the core equipment in the process of transporting such a multiphase medium [1,2]. Otherwise, micro-/nanobubbles can be generated with the aid of a multiphase pump through different formation mechanics [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

et al. 2021

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The turbulence dissipation will cause the increment of energy loss in the multiphase pump and deteriorate the pump performance. In order to research the turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump, the spiral axial flow type multiphase pump is researched numerically in the present study. This research is focused on the turbulence dissipation rate distribution characteristics in the directions of inlet to outlet, hub to rim, and in the circumferential direction of the rotating impeller blades. Numerical simulation based on the RANS (Reynolds averaged Navier–Stokes equations) and the k-ω SST (Shear Stress Transport) turbulence model has been carried out. The numerical method is verified by comparing the numerical results with the experimental data. Results show that the regions of the large turbulence dissipation rate are mainly at the inlet and outlet of the rotating impeller and static impeller, while it is almost zero from the inlet to the middle of outlet in the suction surface and pressure surface of the first-stage rotating impeller blades. The turbulence dissipation rate is increased gradually from the hub to the rim of the inlet section of the first-stage rotating impeller, while it is decreased firstly and then increased on the middle and outlet sections. The turbulence dissipation rate distributes unevenly in the circumferential direction on the outlet section. The maximum value of the turbulence dissipation rate occurs at 0.9 times of the rated flow rate, while the minimum value at 1.5 times of the rated flow rate. Four turning points in the turbulence dissipation rate distribution that are the same as the number of impeller blades occur at 0.5 times the blade height at 0.9 times the rated flow rate condition. The turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump have been studied carefully in this paper, and the research results have an important significance for improving the performance of the multiphase pump theoretically.

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“…Thus, this phenomenon is also attracted widespread attention. [5][6][7] To reveal the TLF and TLV behaviors, numerous scholars investigated on this issue. In the aspect of theory research, Rains 8 considered that the TLF is a jet flow induced by a pressure difference, and established a leakage model.…”

Section: Introductionmentioning

confidence: 99%

Flow behaviors in a Kaplan turbine runner with different tip clearances

Qian¹,

Zhang²,

Wang³

et al. 2021

Advances in Mechanical Engineering

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Tip clearance between the runner blade tip and shroud in a Kaplan turbine is inevitable, and the tip leakage flow (TLF) and tip leakage vortex (TLV) induced by the tip clearance have a considerable effect on the flow behaviors. To reveal the effect of the tip clearance on the flow characteristics, based on the Reynolds time-averaged Navier-Stokes (N-S) equation and the shear stress transfer (SST) k-ω turbulence model, the three-dimensional turbulence flow in a Kaplan turbine is simulated using ANSYS CFX. Meanwhile, the flow laws in the tip clearance are emphatically analyzed and summarized. Results show with the increase of the tip clearance, the negative pressure region in the blade suction side (SS) middle, the SS near the blade tip and the blade tip becomes more and more obvious. In the meantime, the flow behaviors on the blade pressure side (PS) are relatively stable, and the flow separation on the SS near blade tip merges. The larger the tip clearance is, the more obvious the flow separation phenomenon displays. In addition, the TLV is a spatial three-dimensional spiral structure formed by the entrainment effect of the TLF and main flow, and as the tip clearance increases, the TLV becomes more obvious.

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Effect of the inlet gas void fraction on the tip leakage vortex in a multiphase pump

Cited by 30 publications

References 21 publications

Effect of Tip Clearance Size on Tubular Turbine Leakage Characteristics

Effect of Tip Clearance Size on Tubular Turbine Leakage Characteristics

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

Flow behaviors in a Kaplan turbine runner with different tip clearances

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