Numerical study on the internal flow characteristics of an axial-flow pump under stall conditions

In this paper, a numerical investigation was carried out on the performances of a designed axial flow pump for a large cavitation tunnel. From this, the flow characteristics, force, and torque performance of the axial flow pump were investigated, and the rotating speeds of the impeller satisfying the test section speed performances required in the large cavitation tunnel were estimated. The axial flow pump was modeled such that the impeller, stator, and nacelle were located in a cylindrical tunnel. The calculations were carried out for incompressible steady-state turbulent flow considering the impeller rotating. The performance of the pump was confirmed, finding that the head gain was caused by the pressure jump downstream of the pump. The performance of the stator was confirmed to be good enough to refine the tangential flow due to the impeller rotating. To investigate the operating performance of the large cavitation tunnel, the head loss of the entire tunnel without the pump was obtained from a numerical analysis. The operating points were estimated from the specific speed–head coefficient curves, and it was found that the present numerical results were in good agreement with the experiments.

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Flow Characteristics of High-Efficient Axial Flow Pump System

ASME 2015 Power Conference ◽

10.1115/power2015-49300 ◽

2015 ◽

Author(s):

Chao Liu ◽

Fan Yang ◽

Yan Jin ◽

Hua Yang

Keyword(s):

Flow Characteristics ◽

Axial Flow ◽

Internal Flow ◽

Operating Conditions ◽

Optimum Operating ◽

Hydraulic Loss ◽

Pump System ◽

High Efficient ◽

Axial Flow Pump ◽

Flow Pump

Three-dimensional flow-fields in a high-efficient axial flow pump system were simulated by CFD to further study the internal flow characteristics. The internal flow patterns of the pump system were obtained at large, small and optimum operating conditions. The highest efficiency of pump system measured and calculated are 82.57% and 81% respectively at blade angle 0°. For the suction passage, the axial velocity distribution uniformity reach 97.51%, and the hydraulic loss is 0.039m, the pipe efficiency calculated is 98.5% at the optimum operating conditions. The maximum velocity is 1.429 m/s in the range of operating conditions, which meet the requirement of National standard. The performances predicted were compared with measurement results. It was found that the calculated results agree well with the measured results. The overall flow pattern of the pump system is uniform and smooth, and the hydraulic loss is very small which gives the excellent hydraulic performances of pump system.

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An analysis on the flow characteristics of bi-directional axial-flow pump under reverse operation

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650917695447 ◽

2017 ◽

Vol 231 (3) ◽

pp. 239-249 ◽

Cited By ~ 1

Author(s):

Pengfei Ma ◽

Jun Wang

Keyword(s):

Flow Characteristics ◽

Axial Flow ◽

Internal Flow ◽

Optimum Operating ◽

Reverse Direction ◽

Guide Vanes ◽

Flow Loss ◽

Axial Flow Pump ◽

Object Of Study ◽

Flow Pump

When the conventional bent guide vanes are applied to the bi-directional axial-flow pump, its performance declines considerably under reverse operation. Regarding a bi-directional axial-flow pump with high specific speed as the object of study, the variation of both hydraulic performance and internal flow field under reverse operation are analyzed in this paper. The results indicate that both the head and efficiency of the pump will drop greatly and the optimum operating point lean to the lower flow rate when it operates in the reverse direction, mainly due to the prewhirl caused by the guide vanes; the shedding vortex is formed after flow separation occurred near the trailing edge of blade, and its scale keeps increasing in the diffusing pipe during its motion until it collapses in the straight pipe, which is the major causes of the big flow loss and significant decline of the performance under reverse operation.

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Performance and Internal Flow Characteristics of an Axial Flow Pump for a Floating Type Water Treatment System

The KSFM Journal of Fluid Machinery ◽

10.5293/kfma.2014.17.3.052 ◽

2014 ◽

Vol 17 (3) ◽

pp. 52-58

Author(s):

Patrick Mark Singh ◽

Young-Do Choi

Keyword(s):

Water Treatment ◽

Flow Characteristics ◽

Axial Flow ◽

Internal Flow ◽

Treatment System ◽

Water Treatment System ◽

Axial Flow Pump ◽

Type Water ◽

Floating Type ◽

Flow Pump

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Numerical and Experimental Investigation of Internal Flow Characteristics and Pressure Fluctuation in Inlet Passage of Axial Flow Pump under Deflection Flow Conditions

Energies ◽

10.3390/en14175245 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5245

Author(s):

Fan Yang ◽

Zhongbin Li ◽

Yao Yuan ◽

Chao Liu ◽

Yiqi Zhang ◽

...

Keyword(s):

Flow Characteristics ◽

Axial Flow ◽

Reliability And Validity ◽

Internal Flow ◽

Rotation Frequency ◽

Hydraulic Loss ◽

Flow Conditions ◽

Monitoring Point ◽

Axial Flow Pump ◽

Flow Pump

The deflection flow of inlet passage seriously affects the performance of axial flow pump devices, and reduces the operation efficiency and stability of pumping station systems. In this paper, the influence of different deflection angles on the internal flow characteristics and outlet pulsation characteristics of the inlet passage of the vertical axial flow pump are studied. Based on the Reynolds time-averaged N-S equation of the three-dimensional incompressible fluid and the standard k-ε turbulence model, the model axial flow pump device was numerically simulated. Under optimal working conditions (Qbep = 31.04 L/s), the internal flow field of the axial flow pump was analyzed to study the change law of the axial flow pump performance under different deflection angles. Under the flow conditions of 0.6 Qbep, 1.0 Qbep and 1.2 Qbep, the pulsation characteristics of the outlet of inlet passage in axial flow pump at different deflection angles were analyzed. The result shows that with the increase of the deflection angle, the flow pattern of the inlet passage becomes turbulent, forming vortices of different sizes, the hydraulic loss of the inlet passage increases continuously, and the uniformity of the outlet flow velocity of the inlet passage increases first and then decreases. The time-domain waveform of outlet of the inlet passage at the pressure pulsation monitoring point has obvious periodicity, and the dominant frequency of the monitoring point is four times the rotation frequency, which corresponds to the number of impeller blades. It shows that the numerical calculation is in good agreement with the experimental results, which proves the reliability and validity of the numerical simulation calculation.

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The Effect of the Thickness and Angle of the Inlet and Outlet Guide Vane on the Performance of Axial-Flow Pump

Volume 1A, Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES and Hybrid RANS/LES Methods; Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Active Fluid Dynamics and Flow Control — Theory, Experiments and Implementation ◽

10.1115/fedsm2016-7939 ◽

2016 ◽

Author(s):

Sang-Won Kim ◽

Youn-Jea Kim

Keyword(s):

Numerical Analysis ◽

Numerical Study ◽

Guide Vane ◽

Axial Flow ◽

Inlet Guide Vane ◽

Guide Vanes ◽

Pump Performance ◽

Blade Thickness ◽

Axial Flow Pump ◽

Flow Pump

An axial-flow pump has a relatively high discharge flow rate and specific speed at a relatively low head and it consists of an inlet guide vane, impeller, and outlet guide vane. The interaction of the flow through the inlet guide vane, impeller, and outlet guide vane of the axial-flow pump has a significant effect on its performance. Of those components, the guide vanes especially can improve the head and efficiency of the pump by transforming the kinetic energy of the rotating flow, which has a tangential velocity component, into pressure energy. Accordingly, the geometric configurations of the guide vanes such as blade thickness and angle are crucial design factors for determining the performance of the axial-flow pump. As the reliability of Computational Fluid Dynamics (CFD) has been elevated together with the advance in computer technology, numerical analysis using CFD has recently become an alternative to empirical experiment due to its high reliability to measure the flow field. Thus, in this study, 1,200mm axial-flow pump having an inlet guide vane and impeller with 4 blades and an outlet guide vane with 6 blades was numerically investigated. Numerical study was conducted using the commercial CFD code, ANSYS CFX ver. 16.1, in order to elucidate the effect of the thickness and angle of the guide vanes on the performance of 1,200mm axial-flow pump. The stage condition, which averages the fluxes between interfaces and is accordingly appropriate for the evaluation of pump performance, was adopted as the interface condition between the guide vanes and the impeller. The rotational periodicity condition was used in order to enable a simplified geometry to be used since the guide vanes feature multiple identical regions. The shear stress transport (SST) k-ω model, predicting the turbulence within the flow in good agreement, was also employed in the CFD calculation. With regard to the numerical simulation results, the characteristics of the pressure distribution were discussed in detail. The pump performance, which will determine how well an axial-flow pump will work in terms of its efficiency and head, was also discussed in detail, leading to the conclusion on the optimal blade thickness and angle for the improvement of the performance. In addition, the total pressure loss coefficient was considered in order to investigate the loss within the flow paths depending on the thickness and angle variations. The results presented in this study may give guidelines to the numerical analysis of the axial-flow pump and the investigation of the performance for further optimal design of the axial-flow pump.

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Effect of Tip Clearance on Helico-Axial Flow Pump Performance at Off-Design Case

Processes ◽

10.3390/pr9091653 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1653

Author(s):

Nengqi Kan ◽

Zongku Liu ◽

Guangtai Shi ◽

Xiaobing Liu

Keyword(s):

Optimization Design ◽

Flow Characteristics ◽

Axial Flow ◽

Leading Edge ◽

Tip Clearance ◽

Hydraulic Loss ◽

Tip Leakage Flow ◽

Tip Leakage ◽

Axial Flow Pump ◽

Flow Pump

To reveal the effect of tip clearance on the flow behaviors and pressurization performance of a helico-axial flow pump, the standard k-ε turbulence model is employed to simulate the flow characteristics in the self-developed helico-axial flow pump. The pressure, streamlines and turbulent kinetic energy in a helico-axial flow pump are analyzed. Results show that the tip leakage flow (TLF) forms a tip-separation vortex (TSV) when it enters the tip clearance and forms a tip-leakage vortex (TLV) when it leaves the tip clearance. As the blade tip clearance increases, the TLV moves along the blade from the leading edge (LE) to trailing edge (TE). At the same time, the entrainment between the TLV and the main flow deteriorates the flow pattern in the pump and causes great hydraulic loss. In addition, the existence of tip clearance also increases the possibility of TLV cavitation and has a great effect on the pressurization performance of the helico-axial flow pump. The research results provide the theoretical basis for the structural optimization design of the helico-axial flow pump.

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Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

Volume 2: Design, Construction, and Operation Innovations; Compression and Pump Technology; SCADA, Automation, and Measurement; System Simulation; Geotechnical and Environmental ◽

10.1115/ipc1996-1892 ◽

1996 ◽

Author(s):

Takaharu Tanaka

Keyword(s):

Cross Section ◽

Flow Rate ◽

Axial Flow ◽

Internal Flow ◽

Pressure Head ◽

Design Flow ◽

Discharge Valve ◽

Head Gradient ◽

Axial Flow Pump ◽

Flow Pump

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

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