Research on the unstable operating region of axial-flow and mixed flow pump

The results presented here are part of a detailed programme measuring the aerodynamics of a high specific speed mixed flow pump impeller over a wide range of operating conditions, including its behaviour in the unsteady stalled regime. The aim is to elucidate the physics of the flow through such an impeller. The noticeable features are the formation of part-span rotating stall cells having no periodicity and organized structure at reduced flow and also the shifting positions of reversal flow pockets as the flowrate changes. Measurements of loss and its variation with span-wise positions and flowrates enable the variation of local efficiency to be determined. The overall flow picture is similar to that expected in an axial flow impeller, though the present impeller displays a narrow stall hysteresis loop almost right through its operating range.

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Evaluation of Blade Passage Analysis Using Coarse Grids

Journal of Fluids Engineering ◽

10.1115/1.483263 ◽

2000 ◽

Vol 122 (2) ◽

pp. 345-348 ◽

Cited By ~ 11

Author(s):

Steven M. Miner

Keyword(s):

Rotational Speed ◽

Stokes Equations ◽

Axial Flow ◽

Measured Data ◽

Flow Coefficient ◽

Design Parameters ◽

Mixed Flow ◽

Specific Speed ◽

Coarse Grids ◽

Flow Pump

This paper presents the results of a study using coarse grids to analyze the flow in the impellers of an axial flow pump and a mixed flow pump. A commercial CFD code (FLOTRAN) is used to solve the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system. The standard k−ε turbulence model is used. The meshes for this study use 22,000 nodes and 40,000 nodes for the axial flow impeller, and 26,000 nodes for the mixed flow impeller. Both models are run on a SPARCstation 20. This is in contrast to typical analyses using in excess of 100,000 nodes. The smaller mesh size has advantages in the design environment. Stage design parameters for the axial flow impeller are, rotational speed 870 rpm, flow coefficient ϕ=0.13, head coefficient ψ=0.06, and specific speed 2.97 (8101 US). For the mixed flow impeller the parameters are, rotational speed 890 rpm, flow coefficient ϕ=0.116, head coefficient ψ=0.094, and specific speed 2.01 (5475 US). Evaluation of the models is based on a comparison of circumferentially averaged results to measured data for the same impeller. Comparisons to measured data include axial and tangential velocities, static pressure, and total pressure. A comparison between the coarse and fine meshes for the axial flow impeller is included. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that coarse CFD models can be used to accurately predict performance. [S0098-2202(00)02202-1]

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Unstable Operation of a Mixed-Flow Pump and the Influence of Tip Clearance

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-06016 ◽

2011 ◽

Cited By ~ 7

Author(s):

Bart van Esch ◽

Li Cheng

Keyword(s):

Strong Influence ◽

Axial Flow ◽

Flow Region ◽

Tip Clearance ◽

Mixed Flow ◽

Spectral Content ◽

Unsteady Forces ◽

Pump Operation ◽

Numerical Research ◽

Flow Pump

Many mixed-flow and axial flow pumps exhibit a so-called unstable head curve. Due to the risk of instabilities this flow region is usually avoided during pump operation. This paper presents experimental and numerical research on the relation between the instability in the head curve and the magnitude of unsteady hydraulic forces. It is found that there is a strong influence of the extend of the clearance gap between impeller blades and casing. The spectral content of the forces shows evidence of rotating instabilities. It indicates that not only instability of the head curve and unsteady forces are interrelated, but also rotating instabilities play a role in this phenomenon. Results of CFD calculations are presented as well, showing the difficulties in simulating the flow under such conditions.

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Study on the guide impeller of large axial flow pump

International Journal of Multiphase Flow ◽

10.1016/s0301-9322(97)88558-8 ◽

1996 ◽

Vol 22 ◽

pp. 145

Author(s):

J Chen

Keyword(s):

Axial Flow ◽

Axial Flow Pump ◽

Flow Pump

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Rotodynamic pumps. Forces and moments on flanges. Centrifugal, mixed flow and axial flow horizontal and vertical shafts pumps

10.3403/30178833 ◽

2009 ◽

Keyword(s):

Axial Flow ◽

Mixed Flow

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Investigation into the Influence of Division Pier on the Internal Flow and Pulsation in the Outlet Conduit of an Axial-Flow Pump

Applied Sciences ◽

10.3390/app11156774 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6774

Author(s):

Fan Yang ◽

Dongjin Jiang ◽

Tieli Wang ◽

Pengcheng Chang ◽

Chao Liu ◽

...

Keyword(s):

Velocity Distribution ◽

Pressure Pulsation ◽

Axial Flow ◽

Hydraulic Loss ◽

Main Frequency ◽

Starting Position ◽

The Difference ◽

Axial Flow Pump ◽

Outlet Conduit ◽

Flow Pump

The outlet conduit is an important construction connecting the outlet of the pump guide vane and the outlet pool; in order to study the hydraulic performance of the straight outlet conduit of the axial-flow pump device, this paper adopts the method of numerical simulation and analyzes the influence of the division pier on the pressure and velocity distribution inside and near the wall of the straight outlet conduit based on three design schemes. Four pressure pulsation measuring points were arranged in the straight outlet conduit, and the low-frequency pulsation characteristic information inside the straight outlet conduit with and without the division pier was extracted by wavelet packet reconstruction. The results show that the addition of a division pier has an effect on the hydraulic loss, near-wall pressure and velocity distribution in the straight outlet conduit. A small high-pressure zone is formed near the wall at the starting position of the division pier, and a large high-speed zone is formed on the left side at the starting position of the division pier. The length of the division pier has no significant effect on the flow distribution of the straight outlet conduit and the pressure and velocity distribution near the wall. Under different working conditions, each monitoring point has the maximum energy in the sub-band (0~31.25 Hz). With the increase of the flow rate, the total pressure energy of the straight outlet conduit decreases gradually. Under each condition, the difference of the energy proportion of the horizontal monitoring points of the straight outlet conduit is small, and the difference of the energy proportion of the two monitoring points at the top and bottom of the outlet channel is relatively large. The energy of the two monitoring points in the straight outlet conduit with a division pier is smaller than that of the two monitoring points in the straight outlet conduit without a division pier. There are differences in the main frequency and the power spectrum corresponding to the main frequency of the monitoring points in the straight outlet conduit, and the reasonable setting of the division pier is conducive to reducing the pressure pulsation of the flow in the straight outlet conduit and is beneficial to the safe and stable operation of the pump device.

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Study on flow measurement method of vertical axial flow pump based on the relationship between flow and differential pressure of two points in elbow inlet passage

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/304/3/032048 ◽

2019 ◽

Vol 304 ◽

pp. 032048

Author(s):

Xiaoming Zhu ◽

Yonghai Yu ◽

Wei Zhang

Keyword(s):

Flow Measurement ◽

Measurement Method ◽

Axial Flow ◽

Differential Pressure ◽

Axial Flow Pump ◽

The Relationship ◽

Flow Pump

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Unsteady Hydraulic Force in Mixed-Flow Pump with Volute Casing.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.63.3330 ◽

1997 ◽

Vol 63 (614) ◽

pp. 3330-3337 ◽

Cited By ~ 2

Author(s):

Hayato SHIMIZU ◽

Chisachi KATO ◽

Tomoyoshi OKAMURA ◽

Takehiko KOMATSU

Keyword(s):

Mixed Flow ◽

Hydraulic Force ◽

Flow Pump

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Foetal bypass: concepts and controversies

Perfusion ◽

10.1177/026765919801300206 ◽

1998 ◽

Vol 13 (2) ◽

pp. 111-117 ◽

Cited By ~ 2

Author(s):

Joseph J Sistino

Keyword(s):

Heart Defects ◽

Open Heart Surgery ◽

Axial Flow ◽

Right Atrial ◽

Cyclooxygenase Inhibitors ◽

Pump System ◽

Maternal Risk ◽

Valvular Stenosis ◽

Axial Flow Pump ◽

Flow Pump

One of the most controversial and challenging surgical undertakings of the next century promises to be foetal cardiac surgery. Animal studies have been underway for several years to gain an understanding of the physiological mechanisms required to achieve this undertaking. Not since the days of crosscirculation has there been a maternal risk associated with open-heart surgery. The diagnosis of congenital heart defects with foetal ultrasound can now be made as early as 12 weeks gestation. Simple cardiac abnormalities, such as valvular stenosis or atresia, alter intracardiac flow patterns and affect normal cardiac chamber development. Without early intervention, these complex lesions often require major surgical reconstruction, beginning in the neonatal period. Foetal cardiac bypass techniques have evolved from the use of roller pumps and bubble oxygenators primed with maternal blood to the use of an axial flow pump incorporated in a right atrial to pulmonary artery or aortic shunt. Because the blood entering the right atrium is oxygenated by the placenta, an oxygenator in the bypass circuit is probably not needed. The low prime axial flow pump system avoids the dilution of the foetus with the maternal adult haemoglobin and improves the outcome. A major focus of research has concentrated on maintenance of placental blood flow with the use of vasodilators and cyclooxygenase inhibitors. Investigation with primates will be necessary to confirm the placental physiology before human operations can be performed. As the foetal bypass challenges are overcome, there is the potential for a reduction in the number of complex cardiac lesions requiring early surgical intervention in the twenty-first century.

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