Unsteady Radial Forces on the Impeller of a Centrifugal Pump With Radial Gap Variation

2003 ◽  
Author(s):  
Jose´ Gonza´les ◽  
Carlos Santolaria ◽  
Jorge Luis Parrondo ◽  
Joaqui´n Ferna´ndez ◽  
Eduardo Blanco
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Numerical Study ◽  
Unsteady Forces ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Distributions ◽  
Dynamic Forces ◽  
Radial Forces ◽  
Radial Gap

An experimental and numerical study is presented on the unsteady radial forces produced in a centrifugal pump with volute casing. Two impellers with different outlet diameter were considered, which gave radial gaps between blade and tongue of 10% and 15.8% of the impeller radius, respectively. Firstly, the data from pressure fluctuation measurements was processed to obtain the dynamic forces at the blade-passage frequency, for a number of flow-rates. Afterwards, these results were used to check the predictions from a numerical simulation of the pump with the code Fluent. This paper describes the work carried out and summarizes the experimental and the numerical results, for both radial gaps. The steady and unsteady forces at the blade passing frequency obtained by radial integration of the pressure distributions in the shroud side of the pump volute are analysed in detail and similar trends are obtained.

Steady and Unsteady Radial Forces for a Centrifugal Pump With Impeller to Tongue Gap Variation

2005 ◽  
Vol 128 (3) ◽  
pp. 454-462 ◽  
Author(s):  
José González ◽  
Jorge Parrondo ◽  
Carlos Santolaria ◽  
Eduardo Blanco
Keyword(s):  
Centrifugal Pump ◽  
Numerical Results ◽  
Momentum Exchange ◽  
Unsteady Forces ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency ◽  
Wide Range ◽  
Radial Forces ◽  
Similarity Laws

Experimental and numerical studies are presented on the steady and unsteady radial forces produced in a single volute vaneless centrifugal pump. Experimentally, the unsteady pressure distributions were obtained using fast response pressure transducers. These measurements were compared with equivalent numerical results from a URANS calculation, using the commercial code FLUENT. Two impellers with different outlet diameters were tested for the same volute, with radial gaps between the blade and tongue of 10.0% and 15.8% of the impeller radius, for the bigger and smaller impeller diameters, respectively. Very often, pump manufacturers apply the similarity laws to this situation, but the measured specific speeds in this case were found to be slightly different. The steady radial forces for the two impellers were calculated from both the measured average pressure field and the model over a wide range of flow rates in order to fully characterize the pump behavior. Again, a deviation from the expected values applying the similarity laws was found. The data from the pressure fluctuation measurements were processed to obtain the dynamic forces at the blade passing frequency, also over a wide range of flow rates. Afterwards, these results were used to check the predictions from the numerical simulations. For some flow rates, the bigger diameter produced higher radial forces, but this was not to be a general rule for all the operating points. This paper describes the work carried out and summarizes the experimental and the numerical results, for both radial gaps. The steady and unsteady forces at the blade passing frequency were calculated by radial integration of the pressure distributions on the shroud side of the pump volute. For the unsteady forces, the numerical model allowed a separate analysis of the terms due to the pressure pulsations and terms related to the momentum exchange in the impeller. In this way, the whole operating range of the pump was studied and analyzed to account for the static and dynamic flow effects. The unsteady forces are very important when designing the pump shaft as they can produce a fatigue collapse if they are not kept under a proper working value.

The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump

2002 ◽  
Vol 124 (3) ◽  
pp. 784-790 ◽  
Author(s):  
Jorge L. Parrondo-Gayo ◽  
Jose´ Gonza´lez-Pe´rez ◽  
Joaquı´n Ferna´ndez-Francos
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Strong Increase ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Transducers ◽  
Leading Role ◽  
Dynamic Forces ◽  
Response Pressure

An experimental investigation is presented which analyzes the unsteady pressure distribution existing in the volute of a conventional centrifugal pump with a nondimensional specific speed of 0.48, for flow-rates from 0% to 160% of the best-efficiency point. For that purpose, pressure signals were obtained at 36 different locations along the volute casing by means of fast-response pressure transducers. Particular attention was paid to the pressure fluctuations at the blade passage frequency, regarding both amplitude and phase delay relative to the motion of the blades. Also, the experimental data obtained was used to adjust the parameters of a simple acoustic model for the volute of the pump. The results clearly show the leading role played by the tongue in the impeller-volute interaction and the strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions.

Study on Radial Forces of Centrifugal Pumps With Various Collectors

2011 ◽  
Author(s):  
Zhongyong Pan ◽  
Junjie Li ◽  
Shuai Li ◽  
Shouqi Yuan
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Radial Force ◽  
Time Dependent ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Trade Off ◽  
Blade Passage ◽  
Design Choice ◽  
Radial Forces

Numerical simulation is presented to study the steady and unsteady radial forces in a centrifugal pump with various collectors. The radial forces are obtained by integrating the pressure distribution around the impeller circumference. The calculated radial forces both time-dependent and independent at different flow rates caused by the collectors are compared. The results show that some conclusions do not consistent with the conventional experience as the collectors with double volute and vaned volute significantly decrease the radial forces and the radial force close a circle during the period of one blade passage passing. The combination of impeller and double volute is a trade-off design choice as it has significantly decreased the radial forces than that of single volute and its configuration is more compact than that of vaned collector.

Analysis of unsteady radial forces of multistage centrifugal pump with double volute

2018 ◽  
Vol 35 (3) ◽  
pp. 1500-1511 ◽  
Author(s):  
Baoling Cui ◽  
Xiaodi Li ◽  
Kun Rao ◽  
Xiaoqi Jia ◽  
Xiaolin Nie
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Static Pressure ◽  
Radial Force ◽  
Radial Vibration ◽  
Flow Rates ◽  
Content Type ◽  
Blade Passing Frequency ◽  
Multistage Centrifugal Pump ◽  
Radial Forces

Purpose Radial vibration of horizontal centrifugal pump has a close association with radial exciting forces. The purpose of this paper is to analyze the unsteady radial force in multistage centrifugal pump with double volute in detail and investigate the relevance of static pressure, radial force and radial vibration. Design/methodology/approach The unsteady numerical simulation with realizable k-ε turbulence model was carried out for a multistage centrifugal pump with double volute using computational fluid dynamics codes Fluent. The performance tests were conducted by use of a closed loop system and performance curves from numerical simulation agree with that of experiment. Vibration tests were carried out by vibration probes instrumented on the bearing cover of pump near no-driven end. Fast Fourier transform was used to obtain the frequency components of radial forces on the impellers from numerical simulation, which are compared with ones of radial vibration from experiment in Y and Z direction. And the static pressure distributions in the impeller were analyzed under different flow rates. Findings The symmetrical double volute can effectively balance radial forces. The maximum radial force and vibration velocity appear at 0.6 Q among the three flow rates 0.6 Q, Q and 1.2 Q. The frequencies corresponding to relatively large amplitude of vibration velocities and radial forces on the impellers in Y direction are blade passing frequency of the impellers. Blade passing frequency of first-stage impeller and shaft frequency are predominating in Z direction. It indicates that the radial vibration of centrifugal pump is closely related to the unsteady radial force. Originality/value The unsteady radial forces of the impeller in multistage centrifugal pump with double volute were comprehensively analyzed. The radial forces should be considered to balance during the design of multistage centrifugal pump.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

scholarly journals Analyses of Hydrodynamic Radial Forces on Centrifugal Pump Impellers

1988 ◽  
Vol 110 (1) ◽  
pp. 20-28 ◽  
Author(s):  
D. R. Adkins ◽  
C. E. Brennen
Keyword(s):  
Theoretical Model ◽  
Centrifugal Pump ◽  
Substantial Effect ◽  
Operating Conditions ◽  
Pump Impeller ◽  
Pressure Distributions ◽  
Flow Disturbances ◽  
Radial Forces ◽  
Flow Through ◽  
Centrifugal Pump Impeller

Hydrodynamic interactions that occur between a centrifugal pump impeller and a volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of flow in the volute. Flow disturbances at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destabilizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destabilizing hydrodynamic forces.

Fluid-Dynamic Pulsations and Radial Forces in a Centrifugal Pump With Different Impeller Diameters

2005 ◽  
Author(s):  
Eduardo Blanco ◽  
Rau´l Barrio ◽  
Jorge Parrondo ◽  
Jose´ Gonza´lez ◽  
Joaqui´n Ferna´ndez
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Fluid Dynamic ◽  
Front Wall ◽  
Numerical Predictions ◽  
Radial Forces ◽  
Flow Through ◽  
Radial Gap

A study is presented on the numerical computation of the unsteady flow through a single suction and single volute centrifugal pump equipped with three impellers of different outlet diameter. Computations were performed by means of the Fluent code, solving the 3D URANS equations. The study was focused on the effect of varying the impeller-volute radial gap on the flow perturbations associated to the fluid-dynamic blade-tongue interaction. In order to contrast the numerical predictions, an experimental series of tests was conducted for the pump with the bigger impeller, to obtain pressure fluctuation data along the volute front wall. Finally, the results from the numerical simulations were used to compute the radial forces at the blade passing frequency, as a function of flow-rate and blade-tongue radial gap.

The Effect of Impeller Cutback on the Fluid-Dynamic Pulsations and Load at the Blade-Passing Frequency in a Centrifugal Pump

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Raúl Barrio ◽  
Eduardo Blanco ◽  
Jorge Parrondo ◽  
José González ◽  
Joaquín Fernández
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Dynamic Load ◽  
Fluid Dynamic ◽  
Low Flow ◽  
Maximum Magnitude ◽  
Flow Rates ◽  
Numerical Predictions ◽  
Blade Passing Frequency ◽  
Radial Gap

A study is presented on the fluid-dynamic pulsations and the corresponding dynamic forces generated in a centrifugal pump with single suction and vaneless volute due to blade-volute interaction. Four impellers with different outlet diameters, obtained from progressive cutbacks (trimmings) of the greatest one, were successively considered in the test pump, so that the radial gap between the impeller and the volute ranged from 8.8% to 23.2% of the impeller radius. The study was based on the numerical computation of the unsteady flow through the machine for a number of flow rates by means of the FLUENT code, solving the 3D unsteady Reynolds-averaged Navier–Stokes equations. Additionally, an experimental series of tests was conducted for the pump with one of the impellers, in order to obtain pressure fluctuation data along the volute front wall that allowed contrasting the numerical predictions. The data collected from the numerical computations were used to estimate the dynamic radial forces and torque at the blade-passing frequency, as a function of flow rate and blade-tongue radial gap. As expected, for a given impeller diameter, the dynamic load increases for off-design conditions, especially for the low range of flow rates, whereas the progressive reduction of the impeller-tongue gap brings about corresponding increments in dynamic load. In particular, varying the blade-tongue gap within the limits of this study resulted in multiplying the maximum magnitude of the blade-passing frequency radial force by a factor of about 4 for low flow rates (i.e., below the nominal flow rate) and 3 for high flow rates.

scholarly journals Flow Field Analysis and Performance Assessment Inside a Vanned Diffuser of a Laboratory-Type Centrifugal Pump

1970 ◽  
Vol 3 (1) ◽  
pp. 8-15
Author(s):  
Abdelmadjid Atif ◽  
Sara Sami
Keyword(s):  
Numerical Simulation ◽  
Performance Assessment ◽  
Centrifugal Pump ◽  
Design Flow ◽  
Field Analysis ◽  
Experimental Measurements ◽  
Vaned Diffuser ◽  
Pressure Distributions ◽  
Flow Field Analysis ◽  
And Performance

The paper refers to the analysis of flow fields inside a vaned diffuser and performance assessment of a laboratory-type centrifugal pump operating with air. The study deals with numerical simulation of the flow at design flow rate, with focus on velocity and pressure distributions across a diffuser passage. The aim is to highlight the flow structure how it leaves the impeller and evolves through the diffuser to understand the mechanism of pressure recovery. The performance assessment consists of evaluating diffuser effectiveness. The numerical results are compared to experimental measurements for validation.

scholarly journals Development of technological regulation for carbon ironing of iron in 30t ladle. Part 1

2019 ◽  
pp. 129-142
Author(s):  
V.P. Piptyuk ◽  
A.S. Vergun ◽  
S.V. Grekov ◽  
S.E. Samohvalov ◽  
K.S. Krasnikov
Keyword(s):  
Numerical Simulation ◽  
Cast Iron ◽  
Numerical Study ◽  
Thermal Conditions ◽  
Temperature Fields ◽  
Low Carbon ◽  
Cored Wire ◽  
Titanium Slag ◽  
Flow Rates ◽  
Energy Balances

The results of numerical simulation of the carbonization of low-carbon iron as a by-product of the production of titanium slag for the designed unit ladle-furnace (LF) installation as applied to the conditions of PJSC Zaporizhzhya Titanium-Magnesium Combine are presented. The technological regulations have been developed and a numerical study has been carried out on the carburization of metal in a 30-ton ladle at the LF. For the production of commercial pig iron, associated iron-containing waste is used. The purpose of the work is to identify factors of the influence of out-of-furnace processing on technology optimization. A numerical simulation was performed of the carburization technology of liquid low-carbon (up to 2% carbon) cast iron with lump (fraction up to 50 mm) graphite and coke introduced onto the surface of a ladle bath (excluding slag cover). The material and energy balances of the process were carried out, the properties of carburizing materials were studied, and the diffusion coefficient of carbon in a liquid metal was estimated. The results of studies of the hydrodynamic and thermal conditions in the bucket bath of the LF are estimated from the contour diagrams of the flow rates and temperature fields for different flow rates of argon supplied through the bottom and submerged tuyeres. The optimal fractions of carbon-containing materials were determined. It has been shown that treatment on LF with lump graphite requires a shorter duration (≈ 45%) compared with lump coke. To accelerate the process of diffusion dissolution of carbon, it is necessary to periodically (every 3 portions of 70 kg of graphite and coke) heat the melt to a temperature of 1520-1530 ° C. Injection of powdered graphite and coke contributes to a more efficient absorption of carbon and a decrease in the duration of the process (≈ by 1/3). Research continues in the direction of using flux-cored wire for carburizing cast iron at LF.

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