Analysis of unsteady flow and fluid exciting forces of multistage centrifugal pump based on actual size

2021 ◽  
pp. 095765092110232
Author(s):  
Baoling Cui ◽  
Yingbin Zhang ◽  
Yakun Huang ◽  
Zuchao Zhu
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Axial Force ◽  
Radial Force ◽  
Design Flow ◽  
Eddy Simulation ◽  
Axial Forces ◽  
Multistage Centrifugal Pump ◽  
The Difference ◽  
The One

The unsteady flow and fluid exciting force inside the multistage centrifugal pump were analyzed on the basis of large eddy simulation (LES). The reliability of the numerical simulation was verified by the experimental performance. The performance of pump calculated was closer to the experimental one than that by the Reynolds time average turbulence model, and the errors were 0.36% and 1.14% at the design flow rate, respectively. The results showed that the different distribution and magnitude of the inlet velocity at each stage impeller contributed to the difference of the head for each one. With the increase of flow rates from 0.4Q to 1.2Q, the rule of axial forces for each stage was roughly the same but the total axial force increased from 25.02kN to 29.92kN. The radial force in the Z direction was smaller than the one in the Y direction, and the amplitude of the main frequency in the Z direction changed more gently for the double tongue. Adopting back-to-back impeller distributions can effectively reduce the axial force. The symmetric distributed double tongue can reduce the radial force and play a key role in reducing the vibration of the centrifugal pump.

scholarly journals Efficiency improvement and evaluation of a centrifugal pump with vaned diffuser

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982590 ◽  
Author(s):  
Kai Wang ◽  
Yu-cheng Jing ◽  
Xiang-hui He ◽  
Hou-lin Liu
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Energy Performance ◽  
Radial Force ◽  
Design Flow ◽  
Vaned Diffuser ◽  
Original Scheme ◽  
Design Flow Rate

In order to enhance the efficiency of centrifugal pump, the structure of a centrifugal pump with vaned diffuser, whose specific speed is 190, was numerically improved by trimming back-blades of impeller and smoothing sharp corner in annular chamber. The energy performance, the internal flow field, the axial force, the radial force, and the pressure pulsation of the pump were analyzed. Results show that efficiency of the improving scheme 1 under the design flow rate is 77.47%, which can balance 69.82% of the axial force, while efficiency of the improving scheme 2 under the design flow rate is the maximum, which could still balance 62.74% of the axial force. The pressure pulsations of the improving scheme 2 at the typical monitoring points are less than that of the improving scheme 1 and the original scheme. The difference of the radial force peak between the improving scheme 1 and the improving scheme 2 is very small. The vector distributions of the radial force of the improving scheme 1 and the improving scheme 2 are more uniform than that of the original scheme. Considering the efficiency, pressure pulsation, and axial force, experiment measurements on the improving scheme 2 were carried out to verify the effectiveness of the improvement result. Results of energy performance experiment show that efficiency of the improving scheme 2 under the design flow rate is 76.48%, which is 5.26 percentage points higher than that of the original scheme.

Clocking effect in a centrifugal pump with a vaned diffuser

2020 ◽  
Vol 34 (26) ◽  
pp. 2050286
Author(s):  
Fen Lai ◽  
Xiangyuan Zhu ◽  
Yongqiang Duan ◽  
Guojun Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Loss ◽  
Total Pressure ◽  
Radial Force ◽  
Design Flow ◽  
Total Pressure Loss ◽  
Inlet Section ◽  
Centrifugal Pumps ◽  
Installation Angle

The performance and service life of centrifugal pumps can be influenced by the clocking effect. In this study, 3D numerical calculations based on the k-omega shear stress transport model are conducted to investigate the clocking effect in a centrifugal pump. Time-averaged behavior and transient behavior are analyzed. Results show that the optimum diffuser installation angle in the centrifugal pump is [Formula: see text] due to the minimum total pressure loss and radial force acting on the impeller. Total pressure loss, particularly in the volute, is considerably influenced by the clocking effect. The difference in total pressure loss in the volute at different clocking positions is 2.75 m under the design flow rate. The large total pressure loss in the volute is primarily caused by the large total pressure gradient within the vicinity of the volute tongue. The radial force acting on the impeller is also considerably affected by the clocking effect. When the diffuser installation angle is [Formula: see text], flow rate fluctuations in the volute and impeller passage are minimal, and flow rate distribution in the diffuser passage is more uniform than those in other diffuser installation angles. Moreover, static pressure fluctuations in the impeller midsection and the diffuser inlet section are at the minimum value. These phenomena explain the minimum radial force acting on the impeller. The findings of this study can provide a useful reference for the design of centrifugal pumps.

Influence of wall roughness on the static performance and pressure fluctuation characteristics of a double-suction centrifugal pump

2018 ◽  
Vol 232 (7) ◽  
pp. 826-840 ◽  
Author(s):  
Zhifeng Yao ◽  
Min Yang ◽  
Ruofu Xiao ◽  
Fujun Wang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Design Flow ◽  
Experimental Investigations ◽  
Wall Roughness ◽  
Detached Eddy Simulation ◽  
Centrifugal Pumps ◽  
Eddy Simulation ◽  
Static Performance

The unsteady flow field and pressure fluctuations in double-suction centrifugal pumps are greatly affected by the wall roughness of internal surfaces. To determine the wall roughness effect, numerical and experimental investigations were carried out. Three impeller schemes for different wall roughness were solved using detached eddy simulation, and the performance and pressure fluctuations resolved by detached eddy simulation were compared with the experimental data. The results show that the effects of wall roughness on the static performance of a pump are remarkable. The head and efficiency of the tested double-suction centrifugal pump are raised by 2.53% and 6.60% respectively as the wall roughness is reduced by means of sand blasting and coating treatments. The detached eddy simulation method has been proven to be accurate for the prediction of the head and efficiency of the double-suction centrifugal pump with roughness effects. The influence of the roughness on pressure fluctuation is greatly dependent on the location relative to the volute tongue region. For locations close to the volute tongue, the peak-to-peak value of the pressure fluctuations of a wall roughness of Ra = 0.10 mm may be 23.27% larger than the case where Ra = 0.02 mm at design flow rate.

Numerical study on instantaneous radial force of a centrifugal pump for different working conditions

2019 ◽  
Vol 37 (2) ◽  
pp. 458-480
Author(s):  
Xiaoqi Jia ◽  
Sheng Yuan ◽  
Zuchao Zhu ◽  
Baoling Cui
Keyword(s):  
Numerical Simulation ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Working Conditions ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Radial Force ◽  
Leakage Rate ◽  
Content Type ◽  
Three Components

Purpose Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will affect safety reliability of pump operation in severe cases. This paper aims to conduct unsteady numerical computation on one centrifugal pump; thus, unsteady fluid radial force upon the impeller and volute is obtained, so as to study the evolution law of instantaneous radial force, the internal relationship between radial force and pressure pulsation, the relationship among each composition of radial force that the impeller received and the influence of leakage rate of front and back chamber on radial force. Design/methodology/approach The unsteady numerical simulation with SST k-ω turbulence model was carried out for a low specific-speed centrifugal pump using computational fluid dynamics codes FLUENT. The performance tests and pressure tests were conducted by a closed loop system. The performance curves and the pressure distribution from numerical simulation agree with that of the experiment conducted. The unsteady pressure distributions and the instantaneous radial forces induced from unsteady flow were analyzed under different flow rates. Contribution degrees of three components of the radial force on the impeller and the relation between the radial force and leakage rate were analyzed. Findings Radial force on the volute and pressure pulsation on the volute wall have the same distribution tendency, but in contrast to the distribution trend of the radial force on the impeller. In the component of radial force that the impeller received, radial force on the blade accounts for the main position. With the decrease of flow rate, ratio of the radial force on front and back casings will be increased; under large flow rate, vortex and flow blockage at volute section will enhance the pressure and radial force fluctuation greatly, and the pulsation degree may be much more intense than that of a smaller flow rate. Originality/value This paper revealed the relation of the radial force and the pressure pulsation. Meanwhile, contribution degrees of three components of the radial force on the impeller under different working conditions as well as the relation between the radial force and leakage rate of front and rear chambers were analyzed.

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 Rotor-Stator Interaction Induced Pressure Fluctuations: CFD and Hydroacoustic Simulations in the Stationary Components of a Multistage Centrifugal Pump

2007 ◽  
Author(s):  
Stefan Berten ◽  
Philippe Dupont ◽  
Mohamed Farhat ◽  
Francois Avellan
Keyword(s):  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Mode Shapes ◽  
Oscillation Analysis ◽  
Multistage Centrifugal Pump ◽  
Spatially Distributed ◽  
Rotor Stator Interaction ◽  
The One

In a centrifugal pump the interaction between the rotating impeller pressure field and the stationary diffuser pressure field yields pressure fluctuations as the result of a modulation process. These fluctuations may induce hydroacoustic pressure fluctuations in the exit chamber of the pump and could cause unacceptable vibrations. This paper presents a methodology for the prediction of hydroacoustic pressure fluctuations resulting from rotor-stator interaction in a multistage centrifugal pump. The method consists in the one-way coupling of incompressible CFD and hydroacoustic simulations. In a first step the rotorstator pressure fluctuations are calculated using a commercial 3D-RANS CFD-code (CFX 10) for different flow rates. The acoustic simulations are performed in two consecutive steps. Initially a free oscillation analysis using white noise pressure fluctuations is performed, which provides hydroacoustic eigen frequencies and mode shapes of the outlet casing. In a second step the spatially distributed pressure fluctuations from the CFD simulation are used to perform a forced oscillation analysis. This approach allows the prediction of possible standing waves in the hydraulic collection elements in the last stage of multistage pumps.

scholarly journals Effects of impeller trim on performance of two-stage self-priming centrifugal pump

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401769249 ◽  
Author(s):  
Kai Wang ◽  
Zixu Zhang ◽  
Linglin Jiang ◽  
Houlin Liu ◽  
Yu Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Radial Force ◽  
Design Flow ◽  
Two Stage ◽  
Rate Condition ◽  
Application Range ◽  
Save Energy

In order to save energy by broadening its application range, the influence of impeller trim on the performance of a two-stage self-priming centrifugal pump was numerically studied. The hydraulic performance experiments and self-priming experiments were carried out. And the unsteady performance of pressure fluctuation and radial force in the pump was analyzed. The results show that with the increase in impeller trim quantity, the best efficiency point of the pump would move to the small flow rate condition. Under the design flow rate, when both the two stages of the impeller were trimmed by 6%, head of the pump was reduced by 13%, efficiency of the pump was as well decreased by 1.69 percentage points, and self-priming time was increased by 1.7%. Thus, impeller trim can be used to meet the operating requirements in the head range of 94–107 m. With the increase in impellers trim quantity, the pressure fluctuation in the positive channel of the radial guide vane and the volute was smaller, while the radial force on the wall of radial guide vane and volute was also smaller.

scholarly journals Experimental Investigation of Pressure Fluctuation, Vibration, and Noise in a Multistage Pump

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Kai Wang ◽  
Zixu Zhang ◽  
Chen Xia ◽  
Zhongchun Liu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Noise Level ◽  
Pressure Pulsation ◽  
Design Flow ◽  
Monitoring Point ◽  
Characteristic Frequencies ◽  
Noise Characteristics ◽  
The Difference

In order to measure the pressure pulsation, vibration, and noise characteristics of multistage centrifugal pump in different flow rates, a five-stage centrifugal pump was chosen as research object. The results show that the main frequency of pressure pulsation was BPF1, 9APF, BPF2, BPF2, and 9APF. According to the order of monitoring points, the intensity of the pressure fluctuation increased and then decreased, with the strongest fluctuation at monitoring point P2. The peak value of pressure fluctuation in monitoring point P2 was obviously higher than the other monitoring points. The main characteristic frequency of vibration is 4APF, BPF2, 9APF, 2BPF2, 3BPF1, 4BPF1, and 4BPF2. The number of characteristic frequencies at the outlet flange was significantly more than the number of characteristic frequencies at the inlet flange. As the flow rate increased, the vibration of motor gradually increased and the vibration of pump increased at first and then decreased. It reached the minimum vibration level in the design flow rate. Motor contributed the largest amount of noise caused by the pump unit. The noise level of measure point which is close to motor is higher than that of other measure points. As the flow rate increased, the noise incrementally increased, and the difference in noise level between measure points decreased gradationally. When the flow rate was 120 m3/h, the maximum difference value of different noise monitoring points was only 1.7 dB.

Analysis of the Pressure Pulsation and Vibration in a Low-Specific-Speed Centrifugal Pump

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Baoling Cui ◽  
Yingbin Zhang ◽  
Yakun Huang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Vortex Core ◽  
Pressure Pulsation ◽  
Radial Force ◽  
Design Flow ◽  
Low Flow ◽  
Pressure Pulsations ◽  
Low Specific Speed ◽  
Specific Speed

Abstract Unsteady pressure pulsation and fluid force induced by flow instabilities in the centrifugal pump is an important cause of vibration, which is detrimental to the safe operation of the pump. In this study, we numerically investigated the pressure pulsation and radial force in a low-specific-speed centrifugal pump by using the detached-eddy simulation method. We also performed a vibration displacement experiment on the shaft of the centrifugal pump. The vortex identification method was introduced to clarify the internal correlation between unsteady flow structures with pressure pulsations. The results showed that the pressure pulsations at the impeller outlet were closely associated with the periodic vortex shedding from the blade pressure surface. The rotor–stator interaction between a relatively big trailing vortex core and volute tongue generated larger pressure pulsation and radial force in the pump at a low flow rate. Under a large flow rate, the trailing vortex core was easily broken and dispersed, and this resulted in smaller pressure pulsation and radial force compared with that at a low flow rate. Under the design flow rate, the pressure pulsation intensity and the radial force in the impeller were smaller than that under the off-design flow rate. Compared with the spectra between the radial force on the impeller and radial displacement on the shaft, they both presented higher amplitude at the shaft frequency. The vibration of the pump shaft was closely related to the radial force on the impeller.

Investigation on performance of a centrifugal pump with multi-malfunction

2020 ◽  
pp. 146134842094234
Author(s):  
Minggao Tan ◽  
Youdong Lu ◽  
Xianfang Wu ◽  
Houlin Liu ◽  
Xiao Tian
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Flow Characteristics ◽  
Radial Force ◽  
Design Flow ◽  
Vibration Level ◽  
Measuring Point ◽  
Flow Pressure ◽  
Simulation Results ◽  
Peak Value

Herein, the performance and inner flow characteristics of a single-stage single-suction centrifugal pump with multi-malfunctions (broken blade and seal ring abrasion) were determined through tests and numerical simulation. The vibration, inner flow, pressure, and radial force of the centrifugal pump were analyzed in detail. Compared with those of a normal pump, the head and efficiency of the pump with multi-malfunctions decreased by 10.56 and 10.09%, respectively, under the design flow rate. The general vibration level most significantly increased at the foot of the pump. The axial passing frequency of each measuring point increased in varying degrees, and new characteristic frequencies appeared at 5, 2, and 3 axial passing frequencies. The simulation results showed that in the pump with multi-functions, the pressure gradient near the broken blade was distinctly reduced, and the periodicity of the impeller radial force became weaker and more concentrated, thus exhibiting different performance than the normal pump. The peak-to-peak value of the pressure pulsation near the tongue increased by 8.5%, whereas that at the pump outlet decreased by 6.8%. Moreover, a vortex appeared at the inlet and another at the middle of the impeller, and the low-pressure zone near the impeller inlet expanded to the middle of the impeller. The results of this work can be used as reference for pump fault diagnosis.

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