Analysis of the reasons of double suction centrifugal pump’s failure

The issue of a pump operation beyond its recommended range and required flow conditions to the suction flange and consequently failure of double suction axially split centrifugal pump was explained. The increased vibration level, improper configuration of the suction pipeline and used hydraulics were presented. It was also illustrated how to diagnose and solve a problem which after implementation at the target workplace has confirmed the correctness of implemented design solutions.

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Balancing axial force in centrifugal pumps with pump out vanes

E3S Web of Conferences ◽

10.1051/e3sconf/201913701028 ◽

2019 ◽

Vol 137 ◽

pp. 01028

Author(s):

Marek Szlaga

Keyword(s):

Pressure Distribution ◽

Centrifugal Pump ◽

Axial Force ◽

Geometrical Parameters ◽

Centrifugal Pumps ◽

Rear Wall ◽

Pump Operation ◽

Design Solutions

Application of pump out vanes is one of the solutions to reduce hydraulic axial force generated during centrifugal pump operation. This article presents the cause of the occurrence of hydraulic axial force and method of calculating pressure distribution at the rear of the impeller used to design pump out vanes properly. It illustrates results of pump out vanes CFD calculations and its validation by measurements. The article reviews the methods of reducing pressure on the rear wall of the centrifugal pump's rotor using pump out vanes. It presents empirical formulae allowing calculation of pressure depending on the geometrical parameters of the blades. The article presents various design solutions of pump out vanes.

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Investigation of centrifugal pump performance under two-phase flow conditions

International Journal of Multiphase Flow ◽

10.1016/s0301-9322(97)88572-2 ◽

1996 ◽

Vol 22 ◽

pp. 147 ◽

Cited By ~ 1

Author(s):

G Noghrehkar

Keyword(s):

Centrifugal Pump ◽

Two Phase Flow ◽

Phase Flow ◽

Flow Conditions ◽

Two Phase ◽

Pump Performance

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Characterization of Cavitation During Pump Operation Based on Hilbert-Huang Transform

Volume 2: Development and Applications in Computational Fluid Dynamics; Industrial and Environmental Applications of Fluid Mechanics; Fluid Measurement and Instrumentation; Cavitation and Phase Change ◽

10.1115/fedsm2018-83163 ◽

2018 ◽

Author(s):

Hui Sun ◽

Shouqi Yuan ◽

Yin Luo ◽

Bo Gong

Keyword(s):

Centrifugal Pump ◽

Longitudinal Vibration ◽

Process Time ◽

Current Signal ◽

Vibration Signals ◽

Pump Operation ◽

Hilbert Huang Transform ◽

Time Frequency ◽

Cavitation Process ◽

Non Stationary Signal

Cavitation has negative influence on pump operation. In order to detect incipient cavitation effectively, experimental investigation was conducted to through acquisition of current and vibration signals during cavitation process. In this research, a centrifugal pump was modeled for research. The data was analyzed by HHT method. The results show that Torque oscillation resulted from unsteady flow during cavitation process could result in energy variation. Variation regulation of RMS of IMF in current signal is similar to that in axial vibration signal. But RMS of IMF in current signal is more sensitive to cavitation generation. It could be regarded as the indicator of incipient cavitation. RMS variation of IMF in base, radial, longitudinal vibration signals experiences an obvious increasing when cavitation gets severe. Such single variation regulation could be selected as the indicator of cavitation stage recognition. Hilbert-Huang transform is suitable for transient and non-stationary signal process. Time-frequency characteristics could be extracted from results of HHT process to reveal pump operation condition. The contents of current work could provide valuable references for further research on centrifugal pump operation detection.

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Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

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

10.1177/0957650917695672 ◽

2017 ◽

Vol 231 (4) ◽

pp. 290-302 ◽

Cited By ~ 4

Author(s):

Can Kang ◽

Ning Mao ◽

Chen Pan ◽

Yang Zhu ◽

Bing Li

Keyword(s):

Centrifugal Pump ◽

Flow Rate ◽

Pressure Fluctuations ◽

Flow Characteristics ◽

Low Flow ◽

Back Surface ◽

Flow Rates ◽

Pump Operation ◽

Low Specific Speed ◽

Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

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Vibration in a Multistage Centrifugal Pump under Varied Conditions

Shock and Vibration ◽

10.1155/2019/2057031 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 18

Author(s):

Ling Bai ◽

Ling Zhou ◽

Xiaoping Jiang ◽

Qinglong Pang ◽

Daoxing Ye

Keyword(s):

Centrifugal Pump ◽

Vibration Frequency ◽

Vibration Velocity ◽

Major Type ◽

Outlet Section ◽

Flow Conditions ◽

Technical Requirements ◽

Mass Unbalance ◽

Blade Passing Frequency ◽

Multistage Centrifugal Pump

Multistage pumps are intended to improve designs with low-vibration and -noise features as the industry applications increase the technical requirements. In this frame, it becomes really important to fully understand the vibration patterns of these kinds of complex machines. In this study, a vibration test bench was established to examine the vibration and stability of a cantilever multistage centrifugal pump under different flow rates. The vibration spectrum diagrams for the inlet and outlet sections and the pump body were evaluated under varied flow conditions. Results showed the effects of operational conditions on the vibration of the cantilever multistage centrifugal pump. Vibration velocity was primarily caused by mass unbalance at the shut-off flow rate point. Under different flow conditions, the blade passing frequency (BPF) and two times the blade passing frequency (2BPF) were the main excitation frequencies. The vibration frequency of the final pump body remained at the BPF under different flow conditions due to the contact with the outlet section. The major type of vibration frequency for the inlet and outlet was high frequency.

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Unsteady internal flow conditions of mini-centrifugal pump with splitter blades

Journal of Thermal Science ◽

10.1007/s11630-013-0596-z ◽

2013 ◽

Vol 22 (1) ◽

pp. 86-91 ◽

Cited By ~ 11

Author(s):

T. Shigemitsu ◽

J. Fukutomi ◽

K. Kaji ◽

T. Wada

Keyword(s):

Centrifugal Pump ◽

Internal Flow ◽

Flow Conditions

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Radial Thrust of Single-Blade Centrifugal Pump

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

10.1115/ajk2011-06011 ◽

2011 ◽

Cited By ~ 4

Author(s):

Yasuyuki Nishi ◽

Junichiro Fukutomi ◽

Ryota Fujiwara

Keyword(s):

Centrifugal Pump ◽

Flow Rate ◽

Design Flow ◽

Centrifugal Impeller ◽

Cfd Analysis ◽

Shearing Stress ◽

Pump Operation ◽

Grand Total ◽

Conservation Of Momentum ◽

Radial Thrust

A single-blade centrifugal pump is widely used as a sewage pump. However, a single-blade is acted on by a large radial thrust during the pump operation because of the geometrical axial asymmetry of the impeller. Therefore to secure the pump reliability, it is necessary to grasp the radial thrust quantitatively and elucidate a behavior and a generation mechanism. This study investigated the radial thrust acting on a single-blade centrifugal impeller by an experiment and a CFD analysis, and the results clearly indicated the following facts. The fluctuating component of the radial thrust increased as the flow rate changed from the design flow rate to a partial or excessive flow rate. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum and pressure components by applying unsteady conservation of momentum to this impeller. The grand total of these components was in agreement with the radial thrust calculated by integrating the pressure and the shearing stress on the impeller surface. In addition the behavior of each component was shown and the effects of those components that gave to the radial thrust were clarified. The pressure component had the greatest effect on a time-averaged value and a fluctuating component of the radial thrust. The time-averaged value of the inertia component was approximately 0 even if the flow rate changed. But its fluctuating component had a magnitude nearly comparable to the pressure component at a partial flow rate and slightly decreased with increase of the flow rate.

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An Experimental Study on the Gas Entrainment in Horizontally and Vertically Installed Centrifugal Pumps

Journal of Fluids Engineering ◽

10.1115/1.4033029 ◽

2016 ◽

Vol 138 (9) ◽

Cited By ~ 27

Author(s):

Martin Neumann ◽

Thomas Schäfer ◽

André Bieberle ◽

Uwe Hampel

Keyword(s):

Centrifugal Pump ◽

Gas Flow ◽

Gamma Ray ◽

Minor Effect ◽

Centrifugal Pumps ◽

Flow Conditions ◽

Two Phase ◽

Inlet Flow ◽

Pump Performance ◽

Gas Entrainment

In this work, we have studied how gas accumulates in an industrial centrifugal pump under various steady-state two-phase flow conditions. Thereby, we considered both horizontal and vertical pump installation positions. Phase fractions within the impeller region of the pump have been quantitatively disclosed using high-resolution gamma-ray computed tomography (HireCT) and applying time-averaged rotation-synchronized CT scanning technique. The study was made for inlet volumetric gas flow rates between 0% and 5%. To account for different inlet flow conditions, which are assumed to occur during unwanted gas entrainment by hollow vortices, we produced disperse and swirling gas–liquid inlet flows. In this way, the influence of inlet flow boundary conditions on the pump performance as well as gas fraction distributions and gas holdup within the impeller wheel region could be successfully analyzed and compared with respect to the impeller alignment. It was shown that the installation position offers only a minor effect on the pump performance in comparison to the inlet flow conditions. In addition, for the first time, thin gas films at the pressure side of the impeller wheel blades could be visualized in an industrial centrifugal pump.

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Numerical 3D Simulation of the Cavitating Flow in a Centrifugal Pump With Low Specific Speed and Evaluation of the Suction Head

Volume 2D: Turbomachinery ◽

10.1115/gt2014-26089 ◽

2014 ◽

Cited By ~ 3

Author(s):

Phillip Limbach ◽

Marius Kimoto ◽

Christian Deimel ◽

Romuald Skoda

Keyword(s):

Centrifugal Pump ◽

Single Phase ◽

Cavitating Flow ◽

Model Parameters ◽

Pump Efficiency ◽

Phase Flow ◽

Flow Conditions ◽

Single Phase Flow ◽

Low Specific Speed ◽

Specific Speed

A numerical analysis is performed to assess the capability of common simulation methods, in particular Ansys CFX, to predict the performance and NPSH curve of a centrifugal pump at very low specific speed for both, design and off-design conditions. In all cases, we use an entire numerical model containing the impeller, the volute casing, the side chambers as well as suction pipe and pressure pipe. A three-dimensional setup is used, testing the following numerical models: steady, i.e. frozen rotor model, unsteady model accounting for the impeller movement and the relative impeller-volute position, single-phase flow as well as cavitating flow conditions. The global performance of the pump is assessed in terms of pressure head, power consumption and pump efficiency for single-phase flow. Furthermore, the drop of the pump head and Net Positive Suction Head (NPSH) characteristics are analyzed for cavitating flow conditions. Numerical results are validated against experimental data. Regarding non-cavitating flow conditions, the trend of the characteristic curves is well predicted, while absolute performance values differ from measured data significantly. The results of steady and unsteady calculations deviate from each other by less than 2%. Concerning cavitating flow, unsteady simulations have to be performed in particular for overload conditions, in order to obtain convergence of the solver. The trend of the measured NPSH curve is well captured with default cavitation model parameters. For nominal and overload, the predicted NPSH curve underestimates the measured one significantly.

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