Pump Performance Curve Research Articles

How Do You Determine Horsepower on a Pump Curve?

By understanding all of the information provided by a pump performance curve, you can make intelligent decisions about the pump type, size, rotational speed, horsepower, and efficiencies required for a particular system.

Use Pump Performance Curves to Improve Efficiency

Applying pump curve knowledge to real‐world cases can help users troubleshoot problems in the field and improve system performance.

Investigation of the Flow Field and Performances of a Centrifugal Pump at Part Load

Centrifugal pump performance curve instability, characterized by a local dent at part load, can be the consequence of flow instabilities in rotating or stationary parts. Such flow instabilities often result in abnormal operating conditions which can damage both the pump and the system. In order for the pump to have reliable operation over a wide flow rate range, it is necessary to achieve a design free of instability. The present paper focuses on performance curve instability of a centrifugal pump of mid specific speed (ωs = 0.65) for which instability was observed at part load during tests. The geometry used for this research consist of the first stage of a multi-stage centrifugal pump and is composed of a suction bend, a closed-type impeller, a vaned diffuser and return guide vanes. In order to analyse the instability phenomenon, PIV and CFD analysis were performed. Both methods qualitatively agree relatively well. It appears that the main difference before and after head drop is an increase of reverse flow rate at the diffuser passage inlet on the hub side. This reverse flow decreases the flow passing area at the diffuser passage inlet, disallowing effective flow deceleration and impairing static pressure recovery.

Mechanistic modeling and numerical simulation of in-situ gas void fraction inside ESP impeller

When gas is entrained with liquid into an electrical submersible pump (ESP), the in-situ gas void fraction (αG) inside the ESP impeller is closely related to its pressure boosting ability. Due to complex pump geometries, the direct measurement of αG is very difficult to carry out. In this study, a mechanistic model for predicting the in-situ αG inside an ESP impeller is developed and validated by three-dimensional (3D) computational fluid dynamics (CFD) simulations. The pressure increment of ESP obtained from single-phase numerical simulations matches experimental measurement well. With a new bubble size prediction model implemented into multiphase CFD simulations, the calculated ESP pressure increments under gassy flow conditions also agree with experimental pump performance curves. As the inlet gas volumetric fraction (GVF) increases, the ESP boosting pressure deteriorates. The simulated in-situ αG, which is used to verify mechanistic model predictions, increases with bubble size increase and gas density or rotational speed decrease. Based on the radial velocity slippage between gas and liquid phases, the in-situ αG can be determined with GVF, rotational speed, bubble size, and fluid properties etc. Compared with empirical correlations, the proposed mechanistic model can predict in-situ αG better by accounting for the gas-liquid phase interaction using the radial force balance between centrifugal buoyancy and drag forces exerted on a stable bubble.

Numerical simulation and performance analysis of a four-stage centrifugal pump

In this article, performance analysis of a four-stage centrifugal pump is presented and discussed by means of numerical simulation and experimental test methods. Calculation domain in simulation was created based on a four-stage real pump model and meshed with the high density of structured grids according to the grid independence analysis. The numerical simulations under multi-conditions were performed based on standard k-e turbulence and standard wall function. Pump performance curves acquired by numerical simulation and the test are basically coincident; the total head, total power, and efficiency values are similar and changing trend is consistent under the different flow conditions. Flow in first stage is dramatically different compared with other stages. The results present that the four-stage simulation could reflect the real flow more precisely than the two-stage simulation, but also have higher requirements about the computer configuration. To balance the time consuming and numerical accuracy, two-stage simulation is a better choice to predict the pump performance. The results of this study provide the basis and reference for the further improvement of multistage centrifugal pump performance.

Optimising prediction model of centrifugal pump as turbine with viscosity effects

Performance conversion of a centrifugal pump as turbine from the known performance curves in pump mode is vital important in pump selection, power generation and investment assessment, especially under low Reynolds number operation conditions. Effects of Reynolds number on such a performance conversion have not been taken into account so far. In the paper, flow rate, head and output power and hydraulic efficiency conversion factors at zero efficiency/power, 0.8 part-load, best efficiency, 1.2 over-load and maximum flow rate points are defined and extracted from the performance curves of a centrifugal pump as turbine at five viscosities obtained by using CFD simulations. The conversion factors are correlated to impeller Reynolds number and a performance conversion model is proposed by employing 3rd and 4th order polynomials for the output power and head curves. New correlations of flow rate, head and efficiency conversion factors are also attempted in terms of specific speed and efficiency as well as impeller Reynolds number based on the data found in literature. The conversion model is a framework and can be useful for design of pump as turbine and its performance prediction, especially under variable liquid viscosity conditions.

Design of Reverse Flow Blockage Device for Reactor Coolant Pumps

Future Sodium cooled Fast Reactors (SFR) in India, are being designed with 3 Reactor Coolant Pumps (RCP). Reactor Coolant Pumps (RCP) are used in pumping the coolant fluid through the reactor core. As the RCPs are operating in parallel, failure of one pump will result in a significant portion of the pumped coolant to bypass the core via tripped RCP. Thus, the reactor has to be shut down and the tripped RCP has to be replaced, which results in down time. Operation of reactor with only two RCP (2/3 mode) will supplement the power generation. Henceforth, if the flow path through the tripped RCP is made highly resistant as compared to the core, then eventually, flow from the two operating RCPs will go through reactor core. Such a flow blocking/resisting arrangement can also provide the flexibility during reactor startup. A cylindrical shell is designed for closing the suction passage of the pump and the shell is raised or lowered from above the roof slab with the help of tie-rods. The cylindrical shell (sleeve shell) is designed to withstand water hammer shock due to inadvertent sudden closure of the suction passage. To determine the shell thickness, pump performance curves are developed based on reactor operating conditions. The sleeve shell will not be able to perfectly close the suction passage as space is required for movement of sleeve shell over the pump shell, thus a study is performed on incorporating a labyrinth to minimize the leakage.

Study on the effect of the impeller and diffuser blade number on reactor coolant pump performances

In this paper, CFD approach was employed to study how the blade number of impeller and diffuser influences reactor coolant pump performances. The three-dimensional pump internal flow channel was modelled by pro/E software, Reynolds-averaged Naiver-Stokes equations with the k-ε turbulence model were solved by the computational fluid dynamics software CFX. By post-processing on the numerical results, the performance curves of reactor coolant pump were obtained. The results are as follows, with the blade number of the impeller increasing, the head of the pump with different diffuser universally increases in the 8Qn∼1.2Qn conditions, and at different blade number of the diffuser, the head increases with the blade number of the impeller increasing. In 1.0Qn condition, when the blades number combination of impeller and diffuser chooses 4+16, 7+14 and 6+18, the head curves exist singular points. In 1.2Qn condition, the head curve still exists singular point in 6+18. With the blade number of the impeller increasing, the efficiency of the pump with different diffuser universally decreases in the 0.8Qn and 1.0Qn conditions, but in 1.2Qn condition, the efficiency of the pump with different diffuser universally increases. In 1.0Qn condition, the impellers of 4 and 5 blades are better. When the blade number combination of impeller and diffuser choose 4+11, 4+17, 4+18, 5+12, 5+17 and 5+18, the efficiencies relatively have higher values. With the blade number of the impeller increasing, the hydraulic shaft power of the pump with different diffuser universally increases in the 0.8Qn∼1.2Qn conditions, and with the blade number of the diffuser increasing, the power of different impeller overall has small fluctuation, but tends to be uniform. This means the increase of the diffuser blade number has less influence on shaft power.The influence on the head and flow by the matching relationship of the blades number between impeller and diffuser is very complicated, which still need further research.This paper provides a reference for exploring the match relationship between the impeller and diffuser blade number of reactor coolant pump.

How Do You Read a Pump Performance Curve?

Understanding how to read a pump curve is critical to selecting the right pump for a water system. Selecting the right pump will, in turn, maximize pump and system efficiency as well as contribute to overall longer operational life.

The Effect of Viscosity on Performance of a Low Specific Speed Centrifugal Pump

Centrifugal pump delivery head and flow rate drop effectively during the pumping of viscous fluids. Several methods and correlations have been developed to predict reduction rate in centrifugal pump performance when handling viscous fluids, but their results are not in very good agreement with each other. In this study, a common industrial low specific speed pump, which is extensively used in different applications, is studied. The entire pump, including impeller, volute, pipes, front and rear sidewall gaps, and balance holes, is simulated in Computational Fluid Dynamics and 3D full Navier Stokes equations are solved. CFD results are compared with experimental data such as pump performance curves, static pressure in casing, and disk friction loss. Dimensionless angular velocity and leakage rate are investigated in sidewall gap and efficiency variation due to viscosity is studied. The results demonstrate that the behavior of the fluid in sidewall gap is strictly sensitive to viscosity. Increasing viscosity improves the volumetric efficiency by reducing internal leakage through wear rings and balance holes, causing, however, a significant fall in the disk and overall efficiency. Results lead to some recommendations for designing centrifugal pumps which may be used in transferring viscous fluids.

Analytical and Experimental Analysis of the High Pressure Boiler Feed Pump

The present works discuss the comparison between the analytical and experimental performance curve of the high pressure boiler feed pump - a multistage centrifugal pump. The hydraulic loss model stated by J.F. Gulich is widely used for the analytical performance prediction of the single stage centrifugal pumps. In the present work, this methodology is implemented for the analytical performance prediction of the 10-stage industrial centrifugal pump. The given pump is installed as HPBFP (High Pressure Boiler Feed Pump) to carry water from the deaerator to boiler. The H-Q (Head versus Discharge) analytical performance characteristics curve of the pump is compared with the experimental performance characteristics curve. The deviation between the analytical and experimental curve is between 2-13% for the discussed range of discharge. This deviation is due to the assumption of the single dimensional geometry of the different components of the centrifugal pump.

A Critical Analysis on the Lubrication Circuit of a Non-road Diesel Engine by Adopting a 3D and 1D Approaches

The aim if this paper is the analysis of a lubrication circuit adopting two simulation models to study the influence of three different lubrication oils.First, the oils pump performance were analyzed with a tri-dimensional simulation model, realized with the commercial code PumpLinx®, which allowed to obtain the performance curves of the oil pump, varying the oils. Then the lubrication circuit was studied with a 1D model, realized with the commercial code LMS AMESim®, and the behaviour of the lubrication circuit was analyzed in terms of pressure drops and components oil consumption.The adopted oils were: 0W30; 5W40 and10W60. In previous activities, both models showed good correlation with experimental data.Analyzing the models results, it was noted that the pressure behavior in the lubrication circuit is highly influenced by the oil, especially for low engine speed and high temperatures.The adopted methodology, that couples mono-dimensional and tri-dimensional models, allowed to analyze the oil influence in a lubrication circuit, avoiding excessive computational cost, but with an acceptable accuracy

Flow simulation in radial pump impellers and evaluation of slip factor

This work is concerned with the study of the slip phenomenon in centrifugal pumps and the evaluation of its dependence on the flow rate for a four-bladed pump. The finite volume method is used, and the impeller domain is represented by a structured grid topology. The calculations assume a rotationally periodic boundary condition, while the frozen rotor technique is used to model the interaction between the pump impeller and its surrounding volute casing. The simulation uses an implicit time integration of the dynamic equations and is carried out using the commercial ANSYS CFX-solver. Results from the simulation are found in reasonable agreement with the pump performance curve with a maximum relative error of 4% in the range of flow coefficient from 0.8 to 1.2. The calculated values of the slip factor, as a function of the flow rate, show good agreement with the Qiu’s mathematical model while retaining the default value of the defined shape factor F = 0.52. In this particular study, the results show that although the slip factor improves with the increase of either the number of blades or splitter length, the corresponding predicted hydraulic efficiency decreases due to the increasing friction loss.

Numerical Simulation on End Suction Centrifugal Pump Running in Inverse Flow for Microhydro Applications

The initial capital cost for most microhydro projects has always been an overriding issue for self-funded remote communities. The cost will escalate significantly in the absence of local microhydro electromechanical manufacturers. The application of end suction centrifugal pump as turbine will reduce the overall cost, which renders microhydro systems feasible for self-funded projects and are therefore suitable for rural communities. The goal of this study is to design and develop a pump as turbine (PAT) which serves as a substitute to commercial electromechanical components. Numerical analysis of an inverse flow for an end suction centrifugal pump is presented in this paper, which includes the performance curves and hydraulic characteristics of the pump. ANSYS CFX, a commercial CFD software is used to simulate the performance of the pump with specific speed, Ns of 70 units (Euroflo EU50-20). The computational flow domain inside the pump is comprises of impeller, volute and draft tube. Unstructured tetrahedral mesh is used to maintain good surface mesh due to complex flow domain geometries. The governing equations used in the simulations are three-dimensional, incompressible Navier-Stokes and k-ϵ turbulence model under steady-state condition. The simulation results are compared with pump performance curve supplied by the pump manufacturer. The verification results show good agreement for flow rates between 0.7 and 1.3 QBEP. The best efficient point (BEP) for inverse flow is attained at a higher head and flow rate compared to pump mode, whereby the value is found to be 21.55 m and 14.0 l/s, respectively. It is believed that the findings of this study will be useful to predict hydraulic characteristics and performance curves of PAT and the model may be used to identify poor flow characteristics inside the pump. It is recommended that optimization process is carried out using CFD tools in future studies.

Analytical study of pressure losses and fluid viscosity effects on pump performance during monophase flow inside an ESP stage

Abstract With the advancement of offshore oil production in deep waters and increasing distances, the Electrical Submersible Pumping (ESP) system has emerged as an important artificial lift method. However, various pressure losses act in centrifugal pumps, thus reducing the energy transfer efficiency to the pumped fluid. Modeling the effects of different kinds of pressure losses at pump head is a far cry from a straightforward task. In the present work, those losses were obtained to help predicting the ESP system performance. A theoretical model computationally implemented using Formula Translation System (FORTRAN) language was developed to calculate head and pressure losses using equations by different authors, and their combinations, for one specific type of pump and four monophase flowing conditions. In order to validate the methodology, pump performance curves were generated and compared with experimental data. The theoretical modeling results also showed that it is possible to estimate the pumps׳ behavior from equations that depend on geometric factors and flow operating conditions.

3-D Numerical Modeling of MHD Flows in Variable Magnetic Field

3-D numerical simulation of the liquid metal flow affected by the electromagnetic field in the magnetohydrodynamic (MHD) devices is performed. Software package ANSYS has been used for the numerical calculations. The non-stationary problem has been solved taking into account the influence of the metal flow on the electromagnetic field and nonlinear magnetic permeability of the ferromagnetic cores. Simplified calculations with constant magnetic permeability of the ferromagnetic cores have been performed as well. Comparison of these calculations shows that the simulation of the MHD pump can be performed in the linear approximation. The pump performance curve has been derived in this approximation.

On the Performance of Air-Lift Pumps: From Analytical Models to Large Eddy Simulation

The present study investigates a hierarchy of models for predicting the performance of air-lift pumps. Investigated models range from simplified one-dimensional analytical models to large eddy simulation (LES). Numerical results from LES and from two different analytical models are validated against experimental data available from the air-lift pump research program at Alexandria University. Present LES employs the volume of fluid (VOF) method to model the multiphase flow in the riser pipe. In general, LES is shown to provide fairly accurate predictions for the air-lift pump performance. Moreover, numerical flow patterns in the riser pipe are in good qualitative and quantitative agreement with their corresponding experimental patterns and with flow pattern maps available in the literature. On the other hand, analytical models are shown to provide results that are of surprisingly comparable accuracy to LES in terms of predicting the pump performance curve. However, due to the steady one-dimensional nature of these models, they are incapable of providing information about the different flow patterns developing in the riser pipe and the transient nature of the pumping process.

Modelling of flow with cavitation in centrifugal pump

The paper concerns flow modelling in centrifugal pump with special consideration of cavitation phenomena. Cavitation occurs when local pressure drops below the saturation pressure according to the temperature of the flow. Vapour bubbles are created and then they flow through the areas with higher pressure. The bubbles collapse rapidly generating pressure wave, noise and vibration. Working under cavitation condition is very dangerous to a pump and can significantly shorten its lifetime. The investigated centrifugal pump consists of three two-flow rotors and stators working on a single shaft. The modelling process started with grid independence study. When the grid was chosen, the pump performance curve was obtained using the single phase fluid model. Next, using the results from pump performance curve calculations, the cavitation characteristic was obtained. The constant capacity was held when the pressure at the inlet was reduced. The two – phase model was used with Zwart cavitation model. The results indicate that the pump work in safe range of parameters. The analysis also provides wide range of information about the areas of vapour appearance. The most endangered regions are leading edges of rotor. When pressure at the inlet drops to about one third of pressure that calculations started from the cavitation cloud appears in whole rotor. The intense of vapour bubbles creation is greater near the shroud of the pump, rather than near the hub. As cavitation is strongly unsteady phenomena, the transient calculations were performed to check if the results are close to those obtained using the steady state type. The differences are not significant.

Effects of blade rotation angle deviations on mixed-flow pump hydraulic performance

By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point (BEP), the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump Q BEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.

볼류트 원심펌프의 스파이럴 케이싱 - 단면 형상의 영향 -

Centrifugal pump consists of a axis, a impeller and a spiral casing. The impeller is the most important component in centrifugal pump. But to minimize flow loss in discharge passage including spiral casing, the shape of spiral casing is very important also. So, to investigate the effect of shape of the spiral casing on performance curve of pump, the characteristics of spiral casing were studied through numerical analysis for centrifugal pump used on industry field. From the results the rectangular model was showed more loss than the others because of asymmetric flow field.