scholarly journals Experimental Investigation of Transient Characteristics of a Double Suction Centrifugal Pump System during Starting Period

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4135
Author(s):  
Faye Jin ◽  
Zhifeng Yao ◽  
Duanming Li ◽  
Ruofu Xiao ◽  
Fujun Wang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Radial Force ◽  
Operating Conditions ◽  
Resonance Phenomenon ◽  
Pump System ◽  
Transient Characteristics ◽  
Water Transportation ◽  
Blade Frequency ◽  
Broadband Frequency

The starting phase for pumps in water transportation pipelines is crucial and has significant transient characteristics which merit further study in order to evaluate the operational stability of the pumping system. This paper presents the results of a study in which the relative steady operating conditions and starting period of a large double-suction centrifugal pump were monitored in real time, including pressure fluctuations, shaft run-out and vibration at the bearing. The transient characteristics of a double-suction centrifugal pump under different operating conditions have been analyzed using fast Fourier transform (FFT) and continuous wavelet transform (CWT). Results indicate broadband frequency components within the spectrum of pressure fluctuations in the volute casing under all test conditions, and the central frequency of the broadband frequency gradually decreases as flow rate increases and approaches the blade frequency, which is the primary reason for an increase in blade-frequency amplitude. This may produce a vibration frequency that is similar to the natural frequency of a certain part of the double-suction centrifugal pump during the starting period, which causes the resonance phenomenon. The radial force is also large during the starting period, which causes eccentric wear of the seal ring at the impeller inlet.

Numerical Research of the Effect of the Outlet Diameter of Diffuser on the Performance and the Radial Force in a Single-Stage Centrifugal Pump

2014 ◽  
Author(s):  
Jiang Wei ◽  
Li Guojun ◽  
Liu Pengfei ◽  
Zhang Lisheng ◽  
Qing Hongyang
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Numerical Results ◽  
Operating Conditions ◽  
Single Stage ◽  
Navier Stokes ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Vaned Diffuser ◽  
Unsteady Numerical Simulation

In this paper, a single-stage pump with diffuser vanes of different outlet diameters has been investigated both numerically and experimentally. The influence of the diffuser vane outlet diameter on pump hydraulic performance and on the radial force of the impeller is explored. Pumps equipped with three different diffusers but with impellers and volutes of the same parameters were simulated by 3D Navier-Stokes solver ANSYS-FLUENT in order to study the effect of the outlet diameter of vaned diffuser on performance of the centrifugal pump. Structured grids of high quality were applied on the whole computational domain. Experimental results were acquired by prototype experiments and were then compared with the numerical results. Both experimental and numerical results show that the performance of a pump with a diffuser of smaller outlet diameter is better than of bigger outlet diameter under all operating conditions. The radial force imposed on the impeller obtained by unsteady numerical simulation was analyzed. The results also indicated that an appropriate decrease in the outlet diameter of the diffuser vane could increase the radial force.

Pressure Fluctuation of the Low Specific Speed Centrifugal Pump

2012 ◽  
Vol 152-154 ◽  
pp. 935-939 ◽  
Author(s):  
Qiang Fu ◽  
Shou Qi Yuan ◽  
Rong Sheng Zhu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
High Frequency ◽  
Pressure Fluctuations ◽  
Radial Force ◽  
Design Flow ◽  
Rate Condition ◽  
Low Specific Speed ◽  
Specific Speed

In order to study the rules of pressure fluctuation and the radial force under different positions in a centrifugal pump with low specific speed, and to find the relationship between each other, the three-dimensional ,unsteady Reynolds-averaged Navier-stokes equations with shear stress transport turbulent models were solved. The pressure fluctuation was obtained. The results showed that the pressure fluctuations were visible. The pressure fluctuations in the volute were relatively low at the design flow rate condition. The blade passing frequency dominates the pressure fluctuations, high frequency contents were found on the outlet of impeller but no high frequency information occured in casing. The radial force on the impeller was unsteady especially at the small flow rate.

scholarly journals Unsteady Flow Numerical Simulations on Internal Energy Dissipation for a Low-Head Centrifugal Pump at Part-Load Operating Conditions

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2013 ◽  
Author(s):  
Xiaoran Zhao ◽  
Yongyao Luo ◽  
Zhengwei Wang ◽  
Yexiang Xiao ◽  
François Avellan
Keyword(s):  
Energy Dissipation ◽  
Internal Energy ◽  
Centrifugal Pump ◽  
Flow Separation ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Operating Condition ◽  
Part Load ◽  
Rotating Impeller ◽  
Low Head

Dredge pumps are usually operated at part-load conditions, in which the low-solidity centrifugal impeller could experience large internal energy dissipation, related to flow separation and vortices. In this study, SST k-ω and SAS-SST turbulence models were used, in steady and unsteady simulations, for a low-head centrifugal pump with a three-bladed impeller. The main focus of the present work was to investigate the internal energy dissipation in rotating an impeller at part-load operating conditions, related to flow separation and stall. The unsteady nature of these operating conditions was investigated. Performance experiments and transient wall pressure measurements were conducted for validation. A methodology for internal energy dissipation analysis has been proposed; and the unsteady pressure fluctuations were analyzed in the rotating impeller. The internal power losses in the volute and the impeller were mostly found in the centrifugal pump. The rotating stall phenomenon occurred with flow separation and detachment at the part-load operating condition, leading to a dissipation of the internal energy in the impeller. The rotating impeller experienced pressure fluctuations with low frequencies, at part-load operating conditions, while in the design operating condition only experienced rotating frequency.

Effect of outlet impeller diameter on performance prediction of centrifugal pump under single-phase and cavitation flow conditions

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Ahmed Ramadhan Al-Obaidi ◽  
Ali Qubian
Keyword(s):  
Frequency Domain ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Single Phase ◽  
Static Pressure ◽  
Volume Fraction ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Velocity Magnitude

Abstract In this current study, the transient numerical calculations using CFD code are carried out under different outlet impeller diameters for the flow field within a centrifugal pump under single-phase and cavitation conditions. Both qualitative and quantitative analyses are carried out on all of these results in order to better understand the flow structure within a centrifugal pump. Also, the investigations using different outlet impeller diameters configurations relating to the static pressure, velocity magnitude, vapour volume fraction variations, as well as pressure fluctuations in both time and frequency domain at the impeller and volute of the pump are analysed. Velocity and static pressure variations of the pump under different outlet impeller diameters range (200, 210 and 220 mm) are investigated. Reliable model is developed and validated, at various pump operating conditions, to analyse the characteristics of pressure fluctuations in both time and frequency domain. Cavitation occurrence, under different outlet impeller diameters and flow rates, are detected and correlated, using a CFD model (volume fraction distributions). Based on the developed model’s findings, at the set operating conditions ranges, the distribution and impact (cavitation and head-wises) of both the pressure and velocity are analysed. The average pressure fluctuation in the volute for do = 210 mm is higher than for do = 200 mm by about 6.74%, also the maximum pressure fluctuation for do = 220 mm is higher than for do = 210 mm by around 7.4%. Furthermore, the maximum pressure fluctuation in the impeller for do = 210 mm is higher than for do = 200 mm by 12.48%, also for do = 220 mm is higher than for do = 210 mm by 10.8%. The developed CFD models are proved valuable tools in identifying and optimizing the pump performance and characterization. The head for when do = 220 mm is higher than for when do = 200 mm under both single-phase and cavitation conditions by around 14.13% and 14.69%. The maximum pressure fluctuation for do = 200 mm is lower than for do = 210 mm by 41.58%. Furthermore, the maximum pressure fluctuation at the impeller for do = 220 mm is higher than the two models. There is a small clearance between the impeller and the volute for this model, leading to the pressure fluctuation amplitudes being higher than the other above models.

Paper 12: Generation of Hydraulic Noise in Centrifugal Pumps

1966 ◽  
Vol 181 (1) ◽  
pp. 84-108 ◽  
Author(s):  
H. C. Simpson ◽  
R. Macaskill ◽  
T. A. Clark
Keyword(s):  
Rotational Speed ◽  
Pressure Fluctuations ◽  
Noise Spectrum ◽  
Operating Conditions ◽  
Frequency Noise ◽  
Test Results ◽  
Centrifugal Pumps ◽  
Blade Frequency ◽  
Good Agreement ◽  
Dominant Frequencies

The production of hydraulic noise by two types of centrifugal pumps—volute pumps and diffuser pumps—was examined to determine the effect of design and operating conditions on the level of noise generated in the pumped liquid. Experimental work with hydrophones in the exit and entrance to the pumps showed that for both pumps, the dominant frequencies in the noise spectrum were at rotational speed and blade number times rotational speed. It was also found that the distance between cutwater and impeller tip is critical in a volute pump as far as blade frequency noise is concerned. Analysis of the relation between the noise measured by the hydrophones and the fluctuating pressure produced by the pump and the water flow in the inlet and outlet ducts showed that the noise can be interpreted as being directly related to the unsteady flow of water issuing from the impeller. Test results of blade frequency noise levels were correlated with a theoretical analysis for static pressure fluctuations in the pump exit and were shown to be in good agreement. A correlation of general hydraulic noise level with pump specific speed and power consumption was also developed and shown to be reliable to within +2 dB.

scholarly journals An Experimental Study on the Fluid Forces Induced by Rotor-Stator Interaction in a Centrifugal Pump

2003 ◽  
Vol 9 (2) ◽  
pp. 135-144 ◽  
Author(s):  
Shijie Guo ◽  
Hidenobu Okamoto
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Pressure Fluctuations ◽  
Strong Relationship ◽  
Operating Conditions ◽  
Flow Rates ◽  
Fluid Forces ◽  
Large Pressure ◽  
Rotor Stator Interaction ◽  
Frequency Components

The pressure fluctuations and the radial fluid forces acting on the impeller, the pressures in the volute, as well as the vibration of the shaft in a centrifugal pump were measured simultaneously, and their relationship was investigated. Experiments were done for various diffuser vanes, flow rates, and rotating speeds. It was demonstrated that both the blade-pressure fluctuations and the volute static pressures are nonuniform circumferentially (not axisymmetrical) under off-design operating conditions and that the two have a strong relationship. At high flow rates, the blade pressure fluctuations, induced by rotor-stator interactions, are large in areas where the volute static pressure is low. The traveling directions of the rotating pressure waves, the whirling directions of the radial fluid forces, and the most predominant frequency components of both the fluctuations and the forces are discussed, and an equation for predicting them is introduced. It was also noted that large alternating fluid forces are not necessarily associated with large pressure fluctuations. Furthermore, when measuring the radial fluid forces in the rotating frame, other frequency components, in addition to those related to the products of the diffuser vane number and the rotating frequency, may occur due to the circumferential unevenness of the pressure fluctuations on the impeller. These components are predictable.

Influence of U-tube type casing treatment on pressure fluctuations of a centrifugal pump at low flow conditions

2021 ◽  
pp. 2150205
Author(s):  
Yuan Li ◽  
Hua Chen ◽  
Xiangjun Li ◽  
Minghe Jiang ◽  
Guinian Wang
Keyword(s):  
Centrifugal Pump ◽  
Test Performance ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Radial Force ◽  
Low Flow ◽  
Pressure Pulsations ◽  
Casing Treatment ◽  
Tube Type ◽  
Pump Pressure

The existence of pressure pulsations greatly increases the vibration and noise of pumps and harms their service life. In this paper, a casing treatment was employed to explore its impact on the pressure pulsations. A U-tube type groove was created at the inlet end-wall of a centrifugal pump and front cover of the impeller to connect the impeller with the inlet pipe by passing impeller leading edge. An unsteady numerical investigation was launched of the pump with and without this casing treatment, to study its influence on the pressure pulsations inside the pump and the mechanisms behind. The numerical results of the pump without casing treatment was first compared with the test performance of the pump to validate the numerical method, and gave excellent agreements with the test results. The CFD results also showed that the casing treatment increases the head coefficient and efficiency of the pump. Pressure pulsations at a reduced mass flow condition were studied by monitoring unsteady pressure signals generated by the CFD at various locations inside the pump. A Fast Fourier transform (FFT) was performed on the signals. The pump employs a double tongues volute with each tongue covering 180[Formula: see text] circumference. However, the two tongues are not identical with regard to the discharge of the pump. These geometric features of the volute and the pump’s operating condition generate several pressure pulsations in the frequencies of [Formula: see text], [Formula: see text], [Formula: see text] in the original pump. Due to the circumferential unifying capability of the casing treatment and its improvement to the impeller flow, these pulsations at impeller inlet are weakened or disappear when the U-tube is present. The pressure pulsation inside the impeller is less affected by the treatment. The [Formula: see text] pulsation at volute tongues also decreases or disappears for the same reasons, but [Formula: see text] pulsation increases slightly and this is due to the improved pressure recovery in the volute by the treatment which increases the pressure difference across one of the volute tongues. The unsteady radial force of the impeller exerting on journal bearings becomes more uniform and smaller when the casing treatment is employed.

Numerical and Experimental Investigation on the Radial Force Characteristic of a Large Double Suction Centrifugal Pump in a Real Pumping Station

2015 ◽  
Author(s):  
Zhifeng Yao ◽  
Fujun Wang ◽  
Zichao Zhang ◽  
Ruofu Xiao ◽  
Chenglian He
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Radial Force ◽  
Operating Conditions ◽  
Design Flow ◽  
Force Characteristic ◽  
Flow Rates ◽  
Pump Operation ◽  
Pumping Station ◽  
Pump Shaft

The pump operation stability is one of the most important indicators for large discharge pumping stations. Impeller seal rings wear is a key problematic issue. A large double suction centrifugal pump in a real water supply pumping station is numerically and experimentally investigated, of which the seal rings are seriously wore on a fixed location. The pump shaft throws in two orthorhombic directions are measured at flow rates ranging from 0 to 110% of nominal flow rate, as well as the startup and shut down periods. And careful analysis of radial forces under various steady and unsteady conditions is carried out combining with the experimental results. The results show that the value of the shaft displacement obviously increases as the flow rate decreases, especially on the operating conditions with the flow rates below 87% of the design flow rate for the drive end side. The absolute value of the shaft displacement is 0.37mm, which is more than 3 times as large as that at nominal operating condition. There exit a lasting time of large shaft displacements during pump startup and shutdown periods, and the largest value of shaft displacement at the drive end side happens during the pump startup process, which can be increase to 0.95mm. There exists relative large radial force, and the direction of which is exactly the same with the pump shaft displacement at the flow rate from 0.73Qn to 0.32Qn, and also meet the wear locations of the impeller seal rings.

Transient Behavior of a Cavitating Centrifugal Pump at Rapid Change in Operating Conditions—Part 3: Classifications of Transient Phenomena

1999 ◽  
Vol 121 (4) ◽  
pp. 857-865 ◽  
Author(s):  
T. Tanaka ◽  
H. Tsukamoto
Keyword(s):  
Water Column ◽  
Centrifugal Pump ◽  
Rapid Change ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Critical Conditions ◽  
Pump System ◽  
Column Separation ◽  
Cavitation Bubbles ◽  
Flow Mechanisms

Analytical studies were developed on the transient behavior of a cavitating centrifugal pump during the transient operations, including the sudden opening/closure of the discharge valve and the pump startup/shutdown. In order to investigate the mechanism of the low cycle oscillations of both the pressure and the flowrate at a rapid change of the pump system conditions, an unsteady flow analysis was made for the cavitating pump-system by assuming the transient pump performance to be quasi-steady. The calculated unsteady pressure and flowrate during the transient period agree with the corresponding measured time histories. It is shown that the fluctuations of delivery pressure and discharge flowrate at pump rapid startup or sudden valve opening are caused by peculiar oscillating cavitation dynamics inside the pump at rapid increase in flowrate, while the fluctuations at pump rapid shutdown or sudden valve closure are related to the collapse of cavitation bubbles or water column separation in the suction pipe at rapid decrease in flowrate. Moreover, the occurrence of transient fluctuations in pressure and flowrate was predicted by examining the critical condition which creates the occurrence of two different flow mechanisms i.e., (A) oscillating cavitation and (B) water column separation including also the collapse of the cavitation bubbles. These flow mechanisms were represented with two flow models i.e., (A) unsteady cavitating flow incorporating effects of cavitation compliance and mass flow gain factor and expressed by a set of ordinary differential equations solved with the Cardano Method and (B) water-hammer type model including Discrete Free Gas Model and solved with method of characteristics. The calculated critical conditions for the occurrence of the oscillating cavitation and water column separation agree qualitatively with measured ones.

Analysis of Flow-Induced Vibration of the Volute of a Centrifugal Pump Based on Finite Element Method

2010 ◽  
Author(s):  
Jianping Yuan ◽  
Yun Liang ◽  
Shouqi Yuan ◽  
Haifang Xiong ◽  
Ji Pei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Radial Force ◽  
Vibration Response ◽  
Flow Induced Vibration ◽  
Hydraulic Force ◽  
Blade Frequency ◽  
Element Method

During the operation of centrifugal pumps, radial hydraulic force is generated due to non-uniform flow within pumps, which is one of the main sources of the vibration of the centrifugal pump volute. In this paper, based on CFD and finite element method, it was calculated and analyzed that the volute vibration of a centrifugal pump caused by radial hydraulic force. The reason of the occurrence of radial force was analyzed, and by simplifying the theoretical formulas the force was calculated. Then the unsteady flow field of a centrifugal pump was simulated and analyzed under different running conditions by CFD method. Based on the simulation results, the radial hydraulic force of the pump was calculated. Finally, vibration response of the pump volute due to the hydraulic radial force was obtained. By analyzing the vibration response datum, vibration parameters were got such as the displacement, velocity and acceleration of vibration. It was obtained that the main vibration frequencies of the pump volute which is caused by unsteady flow are blade frequency and its harmonic frequencies. The pump volute has a minimum vibration under design flow rate condition, and it has a maximum vibration at the 1.5 times design rated flow whilst the vibration frequency is the integral multiple of the blade frequency. This study is helpful to understand the flow-induced vibration of pump volute and to improve the hydraulic design of the centrifugal pump.

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