scholarly journals Numerical Investigation on the Mechanism of Double-Volute Balancing Radial Hydraulic Force on the Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 689
Author(s):  
Yuan ◽  
Yuan ◽  
Tang
Keyword(s):  
Centrifugal Pump ◽  
Cross Sections ◽  
Performance Test ◽  
Flow Characteristics ◽  
Radial Force ◽  
Transient Pressure ◽  
Force Magnitude ◽  
Hydraulic Force ◽  
Pump Head ◽  
Cfd Method

Double-volute is an effective technique to reduce radial hydraulic force on the centrifugal pump and thereby mitigate the pump-casing vibration induced by unsteady flow characteristics. The mechanism of the double-volute structure balancing radial force on the impeller and volute was investigated on the basis of volute cross-sections by using Computational Fluid Dynamics (CFD) method. The tested performances and simulated inner-flow characteristics of two pumps with single-volute and double-volute were compared in this paper. The performance-test results verify the veracity of CFD method and illustrate that double-volute pump has some losses in terms of pump head and operation efficiency. The numerical simulations reveal that double-volute pump has smaller radial-force magnitude than single-volute pump on the abnormal conditions. Steady pressure field and transient pressure variations of pumps were explored to account for radial-force characteristics of double-volute pump. Compared with the single-volute structure, obvious pressure increases were found in the upper chamber (single part) of the double-volute, while the static pressure decreased in the lower chamber (double chambers). This situation reduces the pressure difference between two volute cross-sections in the collinear radial direction, resulting in smaller radial hydraulic force. Moreover, the transient simulations present the same phenomenon. The radial-forces distribute more uniformly in the double-volute pump, which can alleviate some vibrations.

Flow loss analysis of a two-stage axially split centrifugal pump with double inlet under different channel designs

2019 ◽  
Vol 233 (15) ◽  
pp. 5316-5328 ◽  
Author(s):  
Majeed Koranteng Osman ◽  
Wenjie Wang ◽  
Jianping Yuan ◽  
Jiantao Zhao ◽  
Yiyun Wang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Water Diversion ◽  
Centrifugal Pumps ◽  
Loss Analysis ◽  
Flow Losses ◽  
Water Pumping ◽  
Pumping Stations ◽  
Pump Head ◽  
Flow Loss

The double-stage axially split centrifugal pump is widely used in water diversion and water pumping stations due to their ability to deliver at high heads and large flow rate for long running hours. Their flow characteristics can be greatly influenced by the geometry of the channels between the stages, which is a prominent place for irreversible loss to occur. Numerical investigations were extensively carried out and a comparison was drawn between two multistage axially split centrifugal pumps, with different channel designs between its stages. The reliability of the numerical model was confirmed after a good agreement existed between numerical results and the experiments. Subsequently, entropy generation terms were used to evaluate turbulence dissipation to characterize the flow losses. The modified channels had a great effect on reducing swirl near the impeller eye, thereby improving pump head by 12.5% and efficiency by 4.98% at the design condition. They however induced flow impact, causing an unusual separation, which generated high turbulence dissipation at the blade surfaces. The channels and second stage impeller were identified as major areas for selective optimization since their turbulence dissipation was dominant. Consequently, entropy production analysis with computational fluid dynamics could be relied upon to reveal the loss locations for selective optimization in centrifugal pumps.

The Influence of Vaned Diffuser Outlet Diameters on Operating Performance of a Single-Stage Centrifugal Pump

2018 ◽  
Author(s):  
Xiangyuan Zhu ◽  
Fen Lai ◽  
Liping Zhu ◽  
Guojun Li
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Radial Force ◽  
Hydrodynamic Performance ◽  
Stable Operation ◽  
Vaned Diffuser

To enhance the efficiency and stable operation, the unsteady pressure fluctuations in a centrifugal pump and the radial force on an impeller are investigated for three different vaned diffuser outlet diameters. The steady-state hydrodynamic performance of the centrifugal pump with three different vaned diffuser outlet diameters was experimentally measured. Numerical simulations were used to obtain the hydrodynamic performance of the experimental centrifugal pump based on the Reynolds-averaged Navier-Stokes (RANS) and turbulence models. The numerical results of the hydrodynamic performance were in agreement with the experimental data. The accuracy of the utilized numerical approach was demonstrated. The unsteady flow characteristics of the centrifugal pump were numerically studied. With increasing diffuser vane outlet diameter, the flow field within the volute became more non-uniform, and the pressure fluctuation was more drastic. Moreover, because of the influence of the non-uniform flow field and the pressure fluctuation, the radial force on the impeller increased.

Modeling Viscous Oil Cavitating Flow in a Centrifugal Pump

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Volume Ratio ◽  
Cavitating Flow ◽  
Liquid Volume ◽  
Cavitation Model ◽  
Gas Concentration ◽  
Noncondensable Gas ◽  
Cavitation Performance ◽  
Pump Head ◽  
Cfd Method

Properly modeling cavitating flow in a centrifugal pump is a very important issue for prediction of cavitation performance in pump hydraulic design optimization and application. As a first trial, the issue is explored by using computational fluid dynamics (CFD) method plus the full cavitation model herein. To secure a smoothed head-net positive suction head available (NPSHa) curve, several critical techniques are adopted. The cavitation model is validated against the experimental data in literature. The predicted net positive suction head required (NPSHr) correction factor for viscosity oils is compared with the existing measured data and empirical correlation curve, and the factor is correlated to impeller Reynolds number quantitatively. A useful relation between the pump head coefficient and vapor plus noncondensable gas-to-liquid volume ratio in the impeller is obtained. Vapor and noncondensable gas concentration profiles are illustrated in the impeller, and a “pseudocavitation” effect is confirmed as NPSHa is reduced. The effects of exit blade angle on NPSHr are presented, and the contributions of liquid viscosity and noncondensable gas concentration to the increase of NPSHr at a higher viscosity are identified.

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.

scholarly journals Development and Numerical Performance Analysis of a Pump Directly Driven by a Hydrokinetic Turbine

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4264
Author(s):  
Daqing Zhou ◽  
Huixiang Chen ◽  
Yuan Zheng ◽  
Kan Kan ◽  
An Yu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Degrees Of Freedom ◽  
Draft Tube ◽  
Model Tests ◽  
Cross Sectional ◽  
Practical Applications ◽  
Plain Area ◽  
Pump Head ◽  
Cfd Method ◽  
River Current

Marine and hydrokinetics (MHK) represent an emerging industry with hundreds of potentially viable technologies, such as potential extractable energy from plain area rivers where the water level differences are very small and the traditional water turbine pump (WTP) cannot be used. A suitable WTP, composed of a tubular turbine directly driving a centrifugal pump, was designed and developed based on computational fluid dynamics (CFD) and model tests. Two general design schemes of such river-current (RC)-driven WTP are presented here, obtaining the desired operating parameters of discharge and pump head. A CFD analysis of Scheme B, which employs a radial outlet, allowing additional degrees of freedom for the dimensions of the centrifugal pump, was carried out and verified experimentally by model tests. The minimum deviation of pump head is within ±5%, and the trend of other working conditions is consistent, so the results of the numerical simulation and model tests show good agreement, demonstrating the feasibility of the CFD method for practical applications. Then, using the CFD method, the optimum rotational speed for the turbine was determined, and the turbine draft tube was improved further. With a turbine runner diameter of 0.5 m, the results show best performance at n = 350 r/min. The straight conical draft tube was changed to an elbow draft tube with multiple exits. Additionally, four different cross-sectional shapes were designed for the pump volute, and their effects on the performance of the WTP were analyzed. Finally, the round shape was selected, because of its best performance. The turbine unit has the highest efficiency of 81.2%, at an inlet velocity v = 2.4 m/s, while the pump exhibits the best efficiency of 90.2% at the design discharge and head of 30 l/s and 4.45 m respectively. Overall, the RC-driven WTP makes good use of the kinetic energy of the river current as a power source, solving the inapplicability of traditional WTP in plain areas.

Effect of Relative Impeller-to-Volute Position on Hydraulic Efficiency and Static Radial Force Distribution in a Circular Volute Centrifugal Pump

2000 ◽  
Vol 122 (3) ◽  
pp. 598-605 ◽  
Author(s):  
Daniel O. Baun ◽  
Lutz Ko¨stner ◽  
Ronald D. Flack
Keyword(s):  
Centrifugal Pump ◽  
Relative Position ◽  
Hydraulic Performance ◽  
Radial Force ◽  
Design Flow ◽  
Flow Coefficient ◽  
Geometric Center ◽  
Hydraulic Force ◽  
Radial Thrust ◽  
Force Characteristics

The hydraulic performance and radial hydraulic force characteristics of a circular volute centrifugal pump are strongly affected by the impeller to volute relative position. For a typical design configuration the geometric center of the impeller will be coincident with the volute geometric center. However, assembling a circular volute pump with the impeller center eccentric from the volute center can radically alter both the hydraulic performance and the radial hydraulic force characteristics. In particular, at the design flow coefficient an optimum impeller to volute relative position exists where the efficiency is maximized and the resultant radial force is minimized. At the optimal relative position a 5 percent and a 3.5 percent increase in the efficiency was realized compared to the centered positions for the circular and spiral volutes, respectively. In addition the nondimensional resultant radial force at the design flow coefficient was reduced from 0.045 at the centered position to 0.005 at the optimal position for the circular casing. This value of radial thrust is similar in magnitude to the radial thrust for the spiral volute operating at the design flow coefficient. By assembling a circular volute pump with the appropriate relative impeller to volute position the design simplicity of a circular volute can be utilized without compromising pump hydraulic performance or radial force characteristics as compared to a typical spiral volute. [S0098-2202(00)02303-8]

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.

scholarly journals Effects of Impeller Diameter on High-Speed Rescue Pump

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Yuxing Bai ◽  
Fanyu Kong ◽  
Bin Xia ◽  
Fei Zhao ◽  
Yingying Liu
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Pressure Pulsation ◽  
Rate Increase ◽  
Flow Characteristics ◽  
Radial Force ◽  
Hydraulic Loss ◽  
Ansys Software ◽  
Acceptable Error ◽  
Flow Rate Increase

Impeller diameter is a crucial design parameter of high-speed rescue pumps because it affects the performance and inner flow characteristics of these pumps. In this study, a pump with an impeller diameter of 248 mm was modeled and its performance was tested. Numerical simulations were conducted under steady and unsteady states, in which the sizes of the impeller diameters were designated as 248 mm (original), 235.6 mm (5% trimmed), 223.2 mm (10% trimmed), and 210.8 mm (15% trimmed). ANSYS software was used to test the shear stress transport (SST k-ω) of the four models, and results agreed well with experimental data. Diameter size affected impeller characteristics in both steady and unsteady states. Subsequently, the differences in performance, hydraulic loss, pressure pulsation, and radial force of the impellers were evaluated. In the performance test, the head and efficiency of the pump decreased as impeller diameter was reduced. The result trends are in accordance with the trim law within the acceptable error range. In terms of hydraulic loss, the impeller and diffuser vane components presented opposite trends with flow rate increase. Finally, in terms of pressure pulsation and radial force, the amplitude diminished while periodicity improved as impeller diameter decreased.

Optimization of Nonlinear Pressure-flow Characteristics of a Spring- Loaded Pressure Relief Valve Based on CFD Simulation

2021 ◽  
Author(s):  
Chengshuo Wu ◽  
Shiyang Li ◽  
Qianqian Li ◽  
Peng Wu ◽  
Bin Huang ◽  
...  
Keyword(s):  
Flow Characteristic ◽  
Characteristic Curve ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Relief Valve ◽  
Pressure Flow ◽  
Hydraulic Force ◽  
Middle Chamber ◽  
Valve Opening ◽  
Cfd Method

Abstract In this study, the nonlinear pressure-flow characteristics of a spring-loaded pressure relief valve (PRV) which is used in the automotive fuel supply system for pressure control is analyzed, and its characteristics are improved by means of geometrical modifications of the valve structure. Given the complexity of the coupling mechanism between the valve internal flow characteristics and spring system, a quasi-steady computational fluid dynamics (CFD) method is introduced to predict the nonlinear pressure-flow characteristic curve of the valve and the accuracy is validated by experimental data. The total hydraulic force on the valve spool and diaphragm are divided into three parts according to the position of action and the correlation between the internal flow characteristics, hydraulic force, and pressure-flow characteristics of the valve are explained by CFD analysis and visualization. The result shows that the quasi-steady CFD method can accurately predict the trends of the valve nonlinear pressure-flow characteristic curve which is mainly determined by the hydraulic force produced in the middle chamber of the valve, when the valve opening reaches a certain value, a main vortex would be formulated in the middle chamber and lead to the sudden increase of hydraulic force which causes the fluctuation of the pressure-flow characteristic curve of the valve. It was also found that by increasing the round corner size, the valve opening value of flow pattern change will be promoted and the valve pressure-flow characteristic can be optimized.

Volute Pressure Distribution, Radial Force on the Impeller, and Volute Mixing Losses of a Radial Flow Centrifugal Pump

1960 ◽  
Vol 82 (2) ◽  
pp. 136-143 ◽  
Author(s):  
H. W. Iversen ◽  
R. E. Rolling ◽  
J. J. Carlson
Keyword(s):  
Pressure Distribution ◽  
Centrifugal Pump ◽  
Radial Flow ◽  
Radial Force ◽  
Distribution Analysis ◽  
Pressure Distributions ◽  
Hydraulic Conditions ◽  
Pump Head ◽  
Capacity Performance ◽  
Mixing Losses

A standard volute-type, radial-flow, centrifugal pump was instrumented to obtain the pressure distribution in the volute and also the bearing reactions from the pump hydraulic force transmitted to the shaft. The resultant force from the integrated pressure distribution was found to give a reasonable design approximation of the radial force. An analysis of hydraulic conditions within the volute gave pressure distributions and radial-force magnitudes that were comparable to those measured with certain qualitative interpretations about internal recirculations. In addition, the pressure-distribution analysis furnished an interpretation of the effect of the volute on the pump head-capacity performance with corrections to the impeller head. The predicted head-capacity relationship had the form of the measured pump performance.

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