Effect of Double-Volute Casing on Impeller Radial Force for a Large Double-Suction Centrifugal Pump

2015 ◽  
Author(s):  
Zichao Zhang ◽  
Fujun Wang ◽  
Zhifeng Yao ◽  
Ruofu Xiao
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Operating Conditions ◽  
Force Vector ◽  
Force Fluctuation ◽  
Impeller Outlet ◽  
Rib Structure ◽  
Operation Stability ◽  
Pump Shaft ◽  
The Difference

The operation stability of lager double-suction centrifugal pump is becoming an important issue. High radial force could result in fatigue failure of pump shaft and vibration of impeller. In order to find the effect of double-volute casing on impeller radial force, a double-suction centrifugal pump with two casing configurations is investigated by using CFD approach. The two casings have same geometry, the difference is that one is single-volute casing without dividing rib structure, another is double-volute casing with dividing rid structure. Results show that the dividing rib structure of double-volute casing could result in static pressure surrounding the impeller outlet is symmetry at every operating conditions, this is the reason why radial force of double-volute casing is lower than single-volute casing. The radial force vector diagrams for two casings are all hexagonal. However, radial force of double-volute casing is nearly equal at every operating condition, the centre of hexagon for double-volute casing is nearer to origin of coordinate, these results indicate radial force of double-volute casing is lower than single-volute casing. The rotating frequency and the blade passing frequency dominate the radial force fluctuation in single-volute casing, while both of them are almost not existed in double-volute casing. The results indicate that double-volute casing could significantly reduce radial force fluctuation in double-suction centrifugal pump.

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.

scholarly journals Influence of impeller staggered arrangement on radial force and pressure fluctuation for a double-suction centrifugal pump

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878146 ◽  
Author(s):  
Yu Song ◽  
Zhiyi Yu ◽  
Guangtai Shi ◽  
Xiaobing Liu
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Maximum Amplitude ◽  
Dominant Frequency ◽  
Radial Force ◽  
Pump Efficiency ◽  
Force Vector ◽  
Force Fluctuation ◽  
Staggered Arrangement ◽  
Maximum Improvement

Influence of impeller arrangement on performance, radial force, and pressure fluctuation for a double-suction centrifugal pump is investigated. In comparison of the original impeller with staggered angle α of 0°, the maximum improvement of pump efficiency is 2.19% for impeller with α of 30°, and the maximum improvement of pump head is 1.76% for impeller with α of 20°. The radial force vector on impeller is related to the staggered angle, and the phase angle of radial force vector is equal to the staggered angle. The staggered arrangement can effectively reduce the amplitude of radial force fluctuation. In comparison of case 0, the maximum amplitude of radial force fluctuation for case 30 reduces by 15.8%. The dominant frequencies of the radial force fluctuation for α = 0°, 10°, and 20° are fBP, while the dominant frequency for α = 30° is 2 fBP. An empirical formula is proposed to predict the radial fluctuation amplitude at specific staggered angle. For a point of the volute far from the exit volute, in comparison of case 0, the maximum amplitudes of pressure fluctuation for case 10, case 20, and case 30 are reduced by 13.1%, 49.8%, and 93.3%.

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.

Flow Field and Performance Analysis of a Centrifugal Pump During Unstable Operating Conditions

2019 ◽  
Author(s):  
Romain Prunières ◽  
Chisachi Kato
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Pressure Recovery ◽  
Strong Increase ◽  
Impeller Outlet ◽  
Pump Flow Rate ◽  
Performance Curves

Abstract Centrifugal pump performance curves instability, characterized by a local dent, can be the consequence of flow instabilities in rotating or stationary parts. Such flow instabilities often result in abnormal operating conditions, causing severe problems such as increased pressure pulsation, noise and vibration which can damage both pump and system. For the pump to have reliable operation, it is necessary to understand the onset and the mechanism of the phenomenon resulting in performance curves instability. Present paper focuses on performance curves instability of a centrifugal pump of low specific speed (ωs = 0.65, Ns = 1776) and aims at a better understanding of the mechanism leading to the head drop observed during tests at part load. For that purpose, Computation Fluid Dynamic (CFD) was performed using a Large-Eddy Simulation (LES) approach. The geometry used for present research is in fact the first stage of a multi-stage centrifugal pump and is composed of a suction chamber, a closed-type impeller, a vaned diffuser and return guide vanes to next stage (not included). Leakages at wear ring and stage bush were also included in the computed geometry in order to consider their potential influence on pump stability. The occurrence of the instability in CFD is found at a higher flow rate than in the experiments. It is observed that the pre-swirl angle is under-predicted by several degrees which leads to change the impeller operating conditions. Nevertheless, the analysis of the CFD results is still useful to have a better understanding of the onset of the head drop. When the head drops, a switching of low radial and axial velocities at the impeller outlet from the hub side to the shroud side is observed. This change of flow pattern goes along with a strong increase of the diffuser inlet throat recirculation and the development of stall, that impairs pressure recovery between the impeller outlet and the diffuser inlet. As the pump flow rate is further decreased below the head drop flow rate, recirculation at the diffuser throat extend toward the impeller outlet and impact Euler head. Conversely, the pressure recovery from the impeller outlet to the diffuser inlet throat increases again as the flow velocity slowdown can be effective again. Consequently, the pump head increases again.

scholarly journals The simulation of the service life of the rotary shaft of a centrifugal pump

2019 ◽  
Vol 287 ◽  
pp. 01025
Author(s):  
Madina Isametova ◽  
Rollan Nussipali ◽  
Aysen Isametov
Keyword(s):  
Service Life ◽  
Centrifugal Pump ◽  
Safety Factor ◽  
Operating Time ◽  
Radial Force ◽  
Life Safety ◽  
Centrifugal Pumps ◽  
Computer Technique ◽  
Rotor Shaft ◽  
Pump Shaft

The article describes an automated calculation of such an essential part of a centrifugal pumps the rotor shaft, so the highest level CAD NASTRAN system PATRAN module was used for the analysis. The computational mechanical scheme was drawn up, the axial and radial force acting on the impeller and the pump shaft were determined. The stress for the maximum feed case are determined. The results of the automated strength calculation were used for further analysis of the service life of the rotor shaft of a centrifugal pump. A computer technique for determining the service life of the shaft is given, taking into account the technological, mechanical conditions of operation and taking into account the projected service life equal to the lifetime of the uranium well. Using the automated MSC FATIGUE module, the number of loading cycles was determined, the service life safety factor was determined, which showed the efficiency of the pump throughout the entire operating time of the uranium well.

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 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.

Modeling and suppression of unbalanced radial force for in-wheel motor driving system

2021 ◽  
pp. 107754632110260
Author(s):  
Zhaoxue Deng ◽  
Xu Li ◽  
Tianqin Liu ◽  
Shuen Zhao
Keyword(s):  
Electromagnetic Force ◽  
Switched Reluctance Motor ◽  
Radial Force ◽  
Force Amplitude ◽  
Switched Reluctance ◽  
Driving System ◽  
Coupling Relationship ◽  
Force Fluctuation ◽  
Reluctance Motor ◽  
Road Excitation

Considering the negative vertical dynamics effect of switched reluctance motor on an in-wheel motor driving system, this article presents a modeling and suppression method for unbalanced radial force of the in-wheel motor driving system. To tease out the coupling relationship within the in-wheel motor driving system, this investigation, respectively, explores the principle of unbalanced radial force and the coupling relationship between rotor eccentricity and road excitation based on the suspension response model with unbalanced radial force under road excitation. The switched reluctance motor nonlinear analytical model was fitted by the Fourier series, and its radial electromagnetic force was modeled and analyzed by the Maxwell stress tensor method. To mitigate the influence of radial electromagnetic force fluctuation and unbalanced radial force amplitude value under eccentricity condition on the in-wheel motor driving system, the elitist non-dominated sorting genetic algorithm was adopted to improve radial electromagnetic force fluctuation and unbalanced radial force amplitude value of the switched reluctance motor. The simulation results show that the proposed optimization method can suppress the radial electromagnetic force fluctuation and unbalanced radial force amplitude value, and the negative effect of vertical dynamics of the in-wheel motor driving system is conspicuously mitigated.

Pump Performance Improvement by Restraining Back Flow in Screw-Type Centrifugal Pump

2005 ◽  
Vol 127 (4) ◽  
pp. 755-762 ◽  
Author(s):  
Yasushi Tatebayashi ◽  
Kazuhiro Tanaka ◽  
Toshio Kobayashi
Keyword(s):  
Pressure Fluctuations ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Simple Method ◽  
Back Flow ◽  
Pump Performance ◽  
Impeller Outlet ◽  
Pump Head ◽  
The Difference ◽  
Set Up

The authors have been investigating the various characteristics of screw-type centrifugal pumps, such as pressure fluctuations in impellers, flow patterns in volute casings, and pump performance in air-water two-phase flow conditions. During these investigations, numerical results of our investigations made it clear that three back flow regions existed in this type of pump. Among these, the back flow from the volute casing toward the impeller outlet was the most influential on the pump performance. Thus the most important factor to achieve higher pump performance was to reduce the influence of this back flow. One simple method was proposed to obtain the restraint of back flow and so as to improve the pump performance. This method was to set up a ringlike wall at the suction cover casing between the impeller outlet and the volute casing. Its effects on the flow pattern and the pump performance have been discussed and clarified to compare the calculated results with experimental results done under two conditions, namely, one with and one without this ring-type wall. The influence of wall’s height on the pump head was investigated by numerical simulations. In addition, the difference due to the wall’s effect was clarified to compare its effects on two kinds of volute casing. From the results obtained it can be said that restraining the back flow of such pumps was very important to achieve higher pump performance. Furthermore, another method was suggested to restrain back flow effectively. This method was to attach a wall at the trailing edge of impeller. This method was very useful for avoiding the congestion of solids because this wall was smaller than that used in the first method. The influence of these factors on the pump performance was also discussed by comparing simulated calculations with actual experiments.

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

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