Comparison of Saddle-Shaped Region of Head-Flow Curve between Axial-Flow Pump and Its Corresponding Axial-Flow Pump Device

In engineering, the highest operating head of the pumping station is usually controlled to be slightly lower than the lowest saddle bottom head of the axial-flow pump. However, in the practical operation, it is found that the highest operating head of the pumping station is obviously lower than the saddle bottom head of the pump device, which leads to the reduction of the operating range of the pumping station. To investigate the difference of lowest saddle bottom head between axial flow pump and axial flow pump device and apply it correctly, the energy performance tests of the TJ04-ZL-06 hydraulic model and its corresponding pump device were carried out to obtain the external curves, and numerical simulation was carried out to analyze and compare the internal flow field and pressure distribution. The results show that when the flow rate decreases, the first saddle-shaped region of the axial-flow pump and the saddle-shaped region of the pump device are caused by the decrease of the lift coefficient due to the increase of the attack angle between flow and blade. When the flow rate is less than 0.32Qd, the influence range of backflow in the inlet pipe is large, which leads to the high-pressure zone near the wall of the inlet pressure measurement section during the pump performance test, and hence the second saddle-shaped region of the axial-flow pump is essentially a measurement illusion. It is suggested that the inlet pressure measurement section should be set at least 4Dp away from the inlet flange of the impeller when testing the performance of the axial-flow pump under the condition of small flow rate, and the first saddle bottom head of the axial-flow pump or the saddle bottom head of the corresponding pump device can be considered as the control value of the highest head of the pumping station.

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Numerical and Experimental Investigation of Tip Leakage Vortex Trajectory in an Axial Flow Pump

Volume 1B, Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Fundamental Issues and Perspectives in Fluid Mechanics ◽

10.1115/fedsm2013-16058 ◽

2013 ◽

Author(s):

Desheng Zhang ◽

Weidong Shi ◽

Suqing Wu ◽

Dazhi Pan ◽

Peipei Shao ◽

...

Keyword(s):

Flow Rate ◽

Axial Flow ◽

Tip Clearance ◽

High Speed Photography ◽

Rate Condition ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Starting Point ◽

Axial Flow Pump ◽

Flow Pump

In this paper, the tip leakage vortex (TLV) structures in an axial flow pump were investigated by numerical and experimental methods. Based on the comparisons of different blade tip clearance size (i.e., 0.5 mm, 1mm and 1.5mm) and different flow rate conditions, TLV trajectories were obtained by Swirling Strength method, and simulated by modified SST k-ω turbulence model with refined high-quality structured grids. A high-speed photography test was carried out to capture the tip leakage vortex cavitation in an axial flow pump with transparent casing. Numerical results were compared with the experimental leakage vortex trajectories, and a good agreement is presented. The detailed trajectories show that the start point of tip leakage vortex appears near the leading edge at small flow rate, and it moves from trailing edge to about 30% chord span at rated flow rate. At the larger flow rate condition, the starting point of TLV shifts to the middle of chord, and the direction of TLV moves parallel to the blade hydrofoil. As the increasing of the tip size, the start point of TLV trajectories moves to the central of chord and the minimum pressure in vortex core is gradually reduced.

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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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Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

Mathematical Problems in Engineering ◽

10.1155/2016/6375314 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Fan Yang ◽

Hao-ru Zhao ◽

Chao Liu

Keyword(s):

Prediction Model ◽

Flow Rate ◽

High Efficiency ◽

Guide Vane ◽

Axial Flow ◽

Hydraulic Performance ◽

Operating Conditions ◽

Ann Model ◽

Axial Flow Pump ◽

Flow Pump

In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

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Study on the Performance Improvement of Axial Flow Pump’s Saddle Zone by Using a Double Inlet Nozzle

Water ◽

10.3390/w12051493 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1493

Author(s):

Weidong Cao ◽

Wei Li

Keyword(s):

Flow Rate ◽

Three Dimensional ◽

Axial Flow ◽

Rotating Stall ◽

Stable Operation ◽

Inlet Section ◽

Pump Impeller ◽

Rate Condition ◽

Axial Flow Pump ◽

Flow Pump

The operating range of axial flow pumps is often constrained by the onset of rotating stall. An improved method using a double inlet nozzle to stabilize the performance curve is presented in the current study; a single inlet nozzle and three kinds of double inlet nozzle with different rib gap widths at the inlet of axial flow pump impeller were designed. Three dimensional (3D) incompressible flow fields were simulated, and the distributions of turbulence kinetic energy and velocity at different flow rates located at the inlet section, as well as the pressure and streamline in the impeller, were obtained at the same time. The single inlet nozzle scheme and a double inlet nozzle scheme were studied; the experimental and numerical performance results show that although the cross section is partly blocked in the double inlet nozzle, the head and efficiency do not decline at stable operation flow rate. On small flow rate condition, the double inlet nozzle scheme effectively stabilized the head-flow performance, whereby the block induced by the backflow before the impeller was markedly improved by using a double inlet nozzle. It has also been found that the rib gap width impacts the efficiency curve of the axial flow pump.

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PIV Measurements and CFD Analysis in an Axial-Flow Pump

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37527 ◽

2007 ◽

Author(s):

Fang-Ping Tang ◽

Chao Liu ◽

Ji-Ren Zhou ◽

Hua Yang ◽

Li Cheng

Keyword(s):

Flow Rate ◽

Outer Part ◽

Axial Flow ◽

Operating Conditions ◽

Design Flow ◽

Separation Flow ◽

Mean Velocity ◽

Piv Measurements ◽

Axial Flow Pump ◽

Flow Pump

In this study, an axial flow pump impeller without guide vanes is experimentally investigated. The impeller used in the experiments consists of four blades. The particle image velocimetry technique and a five-hole probe have been used. Measurements of flow velocities in the outer part of the impeller have been made. PIV measurements have been realized in 12 meridian planes between blade-to-blade for design and off-design operating conditions. The meridian velocity is obtained with phase averaged method and the total circumferential mean velocity is obtained with an arithmetical average over the 12 circumferential data. The calculation is based on the CFX-TASC flow CFD code solving the three-dimensional Reynolds-averaged Navier-Stokes equation with RNG k–ε model of turbulence. The paper focuses on the comparisons of the results. Difference for the flow field between numerical and experimental results is small at large and design flow rate, while big difference occurs at small flow rate. It indicates that the numerical model is not suitable for separation flow.

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Oil Film Patterns and Their Relation to Characteristics of an Axial-Flow Pump at Low Flow Rate

Journal of the Society of Mechanical Engineers ◽

10.1299/jsmemag.70.578_359 ◽

1967 ◽

Vol 70 (578) ◽

pp. 359-364

Author(s):

Hitoshi MURAI

Keyword(s):

Flow Rate ◽

Axial Flow ◽

Low Flow ◽

Oil Film ◽

Axial Flow Pump ◽

Flow Pump ◽

Low Flow Rate

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1713 The Internal Flow of Contra-rotating Axial Flow Pump at Partial Flow Rate

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2008.2.0_67 ◽

2008 ◽

Vol 2008.2 (0) ◽

pp. 67-68

Author(s):

Yusuke TSUNENARI ◽

Akinori FURUKAWA ◽

Satoshi WATANABE ◽

Kusuo OKUMA ◽

Satoshi USAMI

Keyword(s):

Flow Rate ◽

Axial Flow ◽

Internal Flow ◽

Axial Flow Pump ◽

Flow Pump

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Air/Water Two-Phase Flow Performance of Contra-Rotating Axial Flow Pump and Rotational Speed Control of Rear Rotor

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2005-77002 ◽

2005 ◽

Cited By ~ 4

Author(s):

Toru Shigemitsu ◽

Akinori Furukawa ◽

Satoshi Watanabe ◽

Kusuo Okuma

Keyword(s):

Flow Rate ◽

Rotational Speed ◽

Two Phase Flow ◽

Axial Flow ◽

Phase Flow ◽

Two Phase ◽

Rate Range ◽

Flow Rate Range ◽

Axial Flow Pump ◽

Flow Pump

An application of contra-rotating rotors, consisting of front and rear rotors rotating in the opposite direction from each other, has been proposed against a demand for developing a higher specific speed axial flow pump with a more compact structure, higher efficiency and higher cavitation performance. As axial flow pumps are used for standby operations of air-lock and air/water mixing discharge to prevent floods, air/water two-phase flow performance of the contra-rotating pump has to be also investigated. In the present paper, therefore, experimental results on air/water two-phase flow performance of a test pump with contra-rotating rotors are shown and compared with those of a conventional axial flow pump, consisting of a front rotor and a rear stator. Even under two-phase flow conditions head characteristic curve of the contra-rotating type has a more strongly negative slope than that of the conventional type. The contra-rotating type maintains higher head and higher efficiency even in the low flow rate range and vice versa in the high flow rate range. This result will be discussed by considering the change of outlet flow from front rotor due to two-phase flow with the help of observed air behavior in the rotors. Then effects of changes of rear rotor rotational speed different from front rotor speed, which is an advantage of the contra-rotating axial flow pump, on two-phase flow performance are examined. Under the condition of constant ratio of air to water flow rates, the head rise of the rear rotor linearly increases with rear rotor rotational speed. Air/water two-phase flow performance of the contra-rotating axial flow pump can be improved by this control procedure for the rear rotor rotational speed.

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