Characteristics Of Centrifugal Pump Research Articles

Numerical Prediction of Pressure Oscillation in a Centrifugal Pump at Shut-off conditions

In order to investigate the pressure fluctuation characteristics of centrifugal pumps under shut-off conditions, a numerical calculation was carried out using Fluent software based on the RNG k-ε turbulence model. The pressure fluctuation characteristics within the volute and impeller flow fields of the centrifugal pump under shut-off conditions were analyzed, and the shut-off head was predicted. The results show that the monitoring points within the volute flow passage exhibit obvious periodic patterns, and their peak pressure fluctuations occur at frequencies that are multiples of the vane passing frequency. Additionally, the closer the monitoring point is to the volute tongue, the greater the amplitude of pressure fluctuation. Furthermore, for monitoring points located on the centerline of the impeller flow passage, the closer they are to the impeller exit, the greater the amplitude of pressure fluctuation.

Prediction of Progressive Erosion Characteristics of Centrifugal Pump Blades Based on Dynamic Boundaries

Abstract The conventional method of fixed boundaries for predicting erosion inadequately reflects the erosion characteristics of centrifugal pumps under realistic operating conditions. In this research, we employ the dynamic boundary method, considering the influence of changes in wall morphology due to erosion on the flow field. We utilize the Euler-Lagrange approach and the E/CRC erosion model, incorporating a dynamic boundary geometry reconstruction strategy, to predict the erosion characteristics of the IS80-50-315 single-stage single-suction centrifugal pump. Solid-liquid two-phase flow calculations are conducted on the pump to predict erosion characteristics under varied operating conditions. The results show that the dynamic boundary-based progressive erosion prediction method realistically forecasts the erosion characteristics of the overflow wall and captures the evolution of blade morphology with erosion time. Erosion intensity on the blade suction surface significantly surpasses that on the pressure surface, guided by particle distribution characteristics in the centrifugal pump flow channel. Particle diameter primarily influences the erosion position of centrifugal pump blades; smaller particles induce erosion in the middle region of the blade, while an increase in particle diameter shifts the severe erosion position towards the impeller outlet direction. At a consistent particle diameter, higher particle concentrations correspond to elevated erosion rates in the blade area. We establish a relationship between the blade mass loss rate and erosion time during 2500 hours of pump operation at the design condition, introducing the blade mass loss rate for convenient assessment and prediction of blade damage in the centrifugal pump.

Research on the internal flow characteristics of centrifugal pump based on streamlined anti-guide vane

Abstract Anti-guide vane is part of the radial guide vane in multi-stage centrifugal pump, and the hydraulic loss of anti-guide vane is the dominant factor affecting the performance of radial guide vane. In this paper, the radial guide vane is chosen as the research object, an optimization scheme of streamlined anti-guide vane is proposed based on the arc-shaped anti-guide vane with inlet angle α=25°. The simulation calculation of multi-stage centrifugal pump is drawn using the SST k-ω turbulence model. and the influence of the streamlined anti-guide vane on the hydraulic performance is studied. The result shows that: Under various flow conditions, the head of the multistage centrifugal pump with streamlined anti-guide vanes is higher than that of the prototype. When the flow rate is 1.3Q, the head is increased by 7.2%. and the efficiency is increased by 2.3%. The amplitude of pressure fluctuation of the streamlined anti-guide vane is significantly decreased at each monitoring point compared to the prototype, indicating that the streamlined anti-guide vane weakens the influence of the pressure fluctuation. Furthermore, the streamlined anti-guide vane enhances the pre-swirl of the inlet fluid to the secondary impeller, reduces the impact loss, and improves the pressurization capacity of the secondary impeller.

Analysis of the effect of cavitation on internal fluid excitation characteristics of centrifugal pumps

To explore the influence of cavitation on the internal fluid excitation characteristics of pumps, numerical simulations and performance testing evaluations were performed on the IS65-50-125 centrifugal pump. The prototype pump's exterior characteristic and cavitation performance curves, as well as its bubble volume distribution, were successfully replicated using numerical computations. The effect of cavitation on the internal pressure pulsation characteristics of the centrifugal pump under various operating situations was comprehensively investigated, indicating a relationship between the degree of cavitation and the root mean square values of pressure pulsation. Special emphasis was placed on the changes in features at intermediate and high frequencies, as well as the processes of rising bubble volume and vortex shedding at the impeller trailing edge on pressure pulsation. To validate the simulation results, a centrifugal pump vibration and noise testing platform was built, and studies on vibration intensity and internal sound field noise were conducted. The experimental results revealed that the vibration intensity and internal sound field sound pressure level of the centrifugal pump rose as cavitation conditions deteriorated, confirming the modeling results. This study's significant innovation is the precise identification of the pump's performance changes under different operating conditions by monitoring pressure pulsation changes at various frequencies, as well as an in-depth discussion of the impact mechanism of cavitation phenomena on the internal fluid excitation behavior of centrifugal pumps. The study demonstrates differences in pressure pulsation characteristics on the suction and pressure sides under various cavitation situations, as well as the process of vortex creation and shedding generated by bubbles in the impeller input channel during severe cavitation. This gives new theoretical basis for pump vibration and noise reduction, as well as significant improvements in centrifugal pump performance and stability.

Study on transient cavitation performance of centrifugal pump based on the influence of rough impeller

This study employs numerical simulation to investigate the transient flow and cavitation performance of centrifugal pumps with rough impellers, validating the numerical method with experimental data. Initially, the effect of blade roughness on the external characteristics of centrifugal pumps is examined. Subsequently, the study specifically addresses the impact of roughness on internal flow characteristics during cavitation, including vapor volume distribution, three-dimensional vortex structures, and vorticity distribution in the impeller channel. Furthermore, the influence of blade roughness on local energy loss is analyzed using entropy production theory. Finally, several monitoring points are arranged in the impeller channel to assess pressure pulsation effects. The results show that blade roughness generally reduces the head and efficiency of centrifugal pumps. During the non-cavitation and cavitation incipient stages, roughness marginally increases the head, with a maximum increase in only 0.1%. Impeller roughness causes vacuole collapse and vortex structure enlargement, disrupting the stable flow path within the channel. Blade roughness also escalates energy loss within impeller components, particularly under full cavitation conditions, where the impeller's entropy production accounts for up to 50%. Pressure pulsation results reveal that while blade roughness can slightly suppress cavitation, it also disturbs the flow field pressure. These insights provide guidance and data support for mitigating roughness and cavitation, the two primary instability factors in centrifugal pump operations.

Analysis on axial force characteristics of variable valve and variable speed adjustment of centrifugal pump

In order to study the evolution mechanism of axial force characteristics of centrifugal pump in the transient process of variable working conditions, the IS80-65-160 centrifugal pump is taken as the research object, and four flow operating points of centrifugal pump 1.0Qr, 0.8Qr, 0.6Qr, and 0.4Qr are selected. Non-constant numerical simulation is carried out, and on the basis that the numerical calculation results of the external characteristics are basically consistent with the experimental results, the changes of the axial force of the impeller during the flow reduction process of the variable valve adjustment and the variable speed adjustment of the centrifugal pump are studied, respectively. The results show that as the flow rate decreases, the force of the variable valve regulating impeller cover plate increases, and the force of the variable speed regulating cover plate decreases. Under the two adjustment methods, the axial force on the pressure surface of the blade becomes smaller, the axial force on the suction surface of the blade is basically unchanged, and the pulsation coefficient of the impeller axial force increases first and then decreases. The axial force pulsation coefficient reaches the maximum value in the variable valve adjustment condition of 0.8Qr and the variable speed adjustment condition of 0.6Qr, respectively, and the axial force on the outer wall of impeller cover plate has the greatest influence on the main frequency axial force ripple coefficient; the axial force acting on the outer wall surface of the front cover plate of the impeller and the inner wall surface of the front and rear cover plates increases with the increase in the radius, The axial force acting on the outer wall surface of the rear cover plate of the impeller has axisymmetrical properties. This study revealed the evolution mechanism of the axial force characteristics of the centrifugal pump impeller during the transient process of variable working conditions, and the research results can provide a reference for improving the stable operation of the centrifugal pump.

Research on Internal Flow and Pressure Fluctuation Characteristics of Centrifugal Pumps as Turbines with Different Blade Wrap Angles

The use of pumps as turbines has been gaining more and more attention in recent years. The present work mainly investigates the influence of blade wrap angle on the internal flow and pressure fluctuation characteristics of centrifugal pumps as turbines. Five different wrap angles (35°,45°, 55°, 65°, and 75°) for a forward-curved impeller were numerically analyzed under multiple operating conditions. The accuracy of numerical simulation was validated by experimental results. The results show that maximum efficiency is achieved with a blade wrap angle of 35°, and the highest efficiency flow point gradually decreases as the blade wrap angle increases. It is found by conducting entropy production theory analysis that the high-entropy production rate regions in PATs are concentrated in the volute tongue and impeller blade inlet regions, and that the entropy production rate at the impeller inlet region increases and then decreases as the blade wrap angle decreases. In addition, pressure pulsation was affected not only by dynamic and static interference but also by an irregular vortex around the impeller; its magnitude under Qt is higher than 0.8Qt for blade wrap angles of 55° and 75°. The primary frequency of pressure pulsation within the impeller is the axial frequency fn and its multiples, and the frequency with the largest amplitude is 3fn. The periodicity of vortices is closely related to the periodicity of pressure pulsation. And it is suggested that a PAT with a 35° blade wrap angle is advantageous for improving the stability of a turbine.

Effect of the Volume Concentration of Binary Mixed Particles on the Flow and Wear Characteristics of Centrifugal Pumps

Solid–liquid two-phase centrifugal pumps are important fluid transport components in production and life. Most of the studies about the influence of solid-phase parameters on fluid transport mostly focus on single-component solid particles. In this work, two kinds of glass beads with particle sizes of 2 mm and 0.4 mm were used to study the effect of the binary mixed particle volume concentration on the internal flow and wear characteristics of a centrifugal pump. The flow distribution of the binary mixed particles in a centrifugal pump and the interactions between the particles and flow components at different volume concentrations (Cv = 5%, Cv = 7.5%, Cv = 10%, Cv = 12.5%, Cv = 15%) were studied using a Computational Fluid Dynamics-Discrete Element Method (CFD-DEM). The research results show that with the increase in particle volume concentration, the head and efficiency of the pump decrease. Additionally, the distributions of the particles with different concentrations in the impeller flow passage were obtained. Moreover, the coupling force of the flow field acting on the particles decreases with the increase in particle concentration and the time it takes to convey small particles decreases with the increase in concentration, while that of large particles decreases first and then increases. Furthermore, the contact force between the particles and the blade changes periodically with time, and the wear of the centrifugal pump is mainly concentrated on the pressure surface of the blade and the wall of the volute outlet side; the wear rate increases as the particle concentration increases.

Study on the form of sealing ring and its sealing characteristics of centrifugal pump

Abstract The sealing ring, also known as the leakage relief ring, is usually composed of a fixed part and a rotating part, which is used to reduce the gap leakage between the rotating part of the pump and the fixed part, and its structural form and clearance value have a great impact on the stability and efficiency of the pump set. In this paper, the sealing ring between the top cover impeller of a centrifugal pump is used as the research object, and the empirical analysis method and numerical simulation method are used to analyse the water sealing characteristics of the sealing ring structure commonly used in five projects from the aspects of leakage amount and energy consumption, and compare. The results show that the labyrinth, stepped and comb tooth sealing rings have good water sealing effect. Aiming at the matching of different sealing gaps and diffusion domains of stepped sealing rings, the influence of sealing structure size on water sealing characteristics was explored, which provided a technical basis for the selection of sealing ring structure and the determination of matching size of centrifugal pump.

Study on dynamic characteristics of centrifugal pump with the development of cavitation under low temperature conditions

Study on dynamic characteristics of centrifugal pump with the development of cavitation under low temperature conditions

Study on rotating stall characteristics of centrifugal pumps based on gamma transition model

The phenomenon of rotating stall in centrifugal pumps is closely associated with the evolution of the blade boundary layer. Aiming to accurately predict the characteristics of the boundary layer, this study investigates the phenomenon of rotating stall in centrifugal pump impellers using the gamma (γ) transition model. The accuracy of the numerical simulation was confirmed by comparing its conclusions with the results of the testing. In calculations considering transition characteristics, the distribution of low-pressure areas inside the impeller is relatively discontinuous, while the pressure distribution is more uniform. However, in calculations without considering transition, the low-pressure regions in neighboring flow channels exhibit a tendency to be interconnected, resulting in a more variable pressure distribution, and the pressure contour at the outlet is closer to parallel. The dynamic characteristics of the centrifugal pump impeller rotating stall were obtained through the dynamic mode decomposition method, including the frequency, structure, and dynamic evolution process of the stall vortex. Through modal reconstruction, it was discovered that the impeller's rotation causes the stall vortex to undergo periodic fluctuations. The stall vortex is not stationary but moves synchronously with the rotation of the blades. At different time points, the stall vortex exhibits periodic changes. At the blade suction entrance, the stall vortex initially appears. Subsequently, multiple vortex structures resulted in channel blockage. After a period of development, the excess vortex structures merge to generate a typical “8” shaped vortex structure and move toward the exit. Finally, the exit stall vortex disappears, and a new vortex structure is generated at the inlet of the blade suction surface.

Internal Flow Characteristics of Centrifugal Pumps under Different Startup Combination Schemes

Pump station engineering is a water conservancy project used for long-distance water transfer, irrigation and drainage, and urban living and industrial water supply. Centrifugal pumps are one of the main pump types commonly used in pumping stations, and their operation is of considerable importance for the safety, stability, and efficient operation of pumping stations. This paper takes a large pumping station with seven centrifugal pump units as the research object and combines experimental research and numerical simulation. The axial flow velocity uniformity, average cross-sectional deviation angle, and hydraulic loss of the pump inlet section are evaluated, and the internal flow characteristics of the pump under different startup combination conditions are analyzed based on entropy generation and vorticity. This study also explores the operational performance of the pump station under different startup combination conditions, revealing the mutual influence mechanism between different startup combinations of pump stations and the internal and external characteristics of centrifugal pumps and introducing the optimal startup combination scheme for the pump station system. Research results indicate that the difference in energy loss of centrifugal pumps under different startup combinations is mainly manifested in the impeller and guide vane flow channels. For the two existing inlet flow channel structures in the pump station, the unit effectively operates when the inlet flow channel is tilted to the left. The optimal startup combination method of the pump station under different startup combinations is determined.

Studying particle transport characteristics in centrifugal pumps under external vibration using CFD-DEM simulation

Centrifugal pumps play a crucial role in deep-sea mining systems. In the marine environment, external vibrations induced by ocean currents and waves can impact the particle transport characteristics of centrifugal pumps in mining systems. CFD-DEM coupling simulations were conducted to simulate operating conditions with external vibration frequencies of 5, 10, and 15 Hz. The study reveals that in the suction chamber, with increasing vibration frequency, the dynamic number of particles decreased, and the percentage of particles with greater velocities than the fluid velocity increased. In the impeller channel, with increasing vibration frequency, the number of collisions among particles and pressure surface of the impeller decreased, and the average energy loss per collision increased. Therefore, external vibrations provide additional kinetic energy for particles, reduce the deposition effects of particles, and improve the pass-ability of particles. This paper can provide theory and engineering support for operation of deep-sea mining centrifugal pumps.

INCREASING THE LEVEL OF ENVIRONMENTAL SAFETY OF PUMPING UNITS BY ENERGY SAVING DURING REGULATION

The relevance of improving calculation methods for pumping units of hydraulic systems in order to save energy and correspondingly increase their level of environmental safety is substantiated. To speed up hydraulic calculations and increase their accuracy, it is proposed to approximate the existing characteristics of centrifugal pumps, which are usually presented in the equipment passport in graphic form, with a quadratic parabola. The general equations for the analytical determination of the working point parameters, the construction of the pressure characteristics of the pump at a new rotation frequency and the formula for the geometric location of the tops of the pressure characteristics for different rotation frequencies of the impeller were obtained. It has been proven that with frequency control, the pump characteristic shifts equidistantly along the parabola of proportionality. In a similar way, the characteristics of the pump are affected by the casing of the impeller. An equation has been obtained that allows, without resorting to the grapho-analytical method, to calculate the change in the characteristics of the pump with a proportional change in all its dimensions and a constant frequency of rotation and the equation of the curve of similar modes. This curve is proposed to be called the similarity curve. It is shown that the velocity coefficient is a constant value along the polynomial curve. On the basis of the obtained results, a method of comparative analysis of the energy efficiency of the regulation of the pumping unit by changing the rotation frequency and proportionally changing all dimensions of the impeller is proposed. The application of the method is demonstrated on concrete examples. Achieving the highest efficiency of the pumping unit ensures the lowest energy consumption, thus minimizing emissions of harmful substances into the atmosphere. Keywords: environmental safety, efficiency, centrifugal pumps, flow regulation, hydraulic resistances, change of rotation frequency, laws of similarity, laws of proportionality

Correlation study between internal flow and vibration characteristics in centrifugal pumps at different cavitation levels

The vibration signal is commonly used to detect the cavitation phenomenon in centrifugal pumps in order to investigate the vibration characteristics of centrifugal pumps with different cavitation degrees and then provide the basis for predicting the critical cavitation point of the pump in advance. This paper takes ns = 35 centrifugal pump as the research object and establishes the quantitative relationship between vorticity and entropy generation and vibration energy by studying the internal flow and vibration response of the centrifugal pump under different cavitation degrees. The study shows that with the development of cavitation, the bubble volume inside the impeller channel gradually increases, and vortices with a larger area appear inside the channel and gradually move toward the impeller outlet. The vorticity and entropy generation of the secondary information of the internal flow field during cavitation have a good third-order fit to the vibration energy, and with the increase in the vorticity and entropy generation, there exists a relationship of a third-order polynomial that first increases and then slows down and finally increases rapidly.

Research on the Performance Characteristics and Unsteady Flow Mechanism of a Centrifugal Pump under Pitch Motion

Pitch motion is the key factor affecting the performance characteristics of centrifugal pumps on board ships and exacerbates hydraulic excitation to induce the unsteady vibration of pump units. A hydraulic test platform with swing motion is established to explore the effects of pitch motion on a pump’s performance characteristics. An obvious hump zone exists in the head characteristic curve in the low-flow-rate condition due to the pitch motion. The pump head in the shut-off condition has a significant decrease due to the pitch motion, compared to the static state. The head decrease gradually increases as the maximum pitch angle increases or the pitch period shortens. Specifically, the head in the rated flow condition decreases by 6.3 % to reach a minimum at the maximum pitch angle of 20 degrees in a period of 5 s. Based on a multiple-reference coordinate system, a large eddy simulation with a shear-modified eddy viscosity model is employed to simulate inner flow characteristics under the influence of pitch motion. A distinct vortex flow appears near the blade suction surface and becomes increasingly turbulent as the pitch period shortens. The pitch motion intensifies the unsteady stretching and deformation of vortices. The periodic variations in fluid-induced pressure over time present parabolic features, and the amplitude in the frequency domain reaches its maximum value within a pitch period of 5 s.

Transient Internal Flow Characteristics of Centrifugal Pump During Rapid Start-Up

Transient Internal Flow Characteristics of Centrifugal Pump During Rapid Start-Up

Simulation study on the flow-induced vibration and noise in marine centrifugal pumps

Due to the three-dimensional non-axisymmetric shape of the volute, its interaction with the impeller increases the internal flow field complexity and instability of the marine centrifugal pump, representing the main reason for pump body vibration and hydraulic noise. First, the basic principle of fluid machinery noise calculation was explained based on the Lighthill acoustic analogy method and Curle’s theory. Then, the fluid pressure pulsation and flow characteristics of centrifugal pumps were analyzed using the Fluent software, after which the Actran software was used to examine the flow-induced vibration noise properties. The results showed that the clearance size significantly impacted the pump head, while the peak value of the flow-induced vibration response was mainly twice the blade frequency. Although a larger ring clearance increased the structural vibration, it had little impact on the sound pressure level changes in the external sound field. The results provided a new method for the structural optimization and low-noise design of marine centrifugal pumps.

Investigation on stall characteristics of marine centrifugal pump considering transition effect

Marine centrifugal pumps are used as boiler feed pumps and condensate pumps in ocean engineering. Centrifugal pump stall is a transient flow structure, which may disrupt the uniformity of the flow field and have destructive effects on the pump. Centrifugal pump simulations are usually limited to the application of turbulence, ignoring the transition characteristics of the blade boundary layer. Aiming at the transient characteristics of centrifugal pump stall vortex, the calculation strategy considering the transition effect is established. This strategy determines the near-wall mesh based on the transition flow parameters and is applied to calculate the centrifugal pump stall for the first time. It is found that at deep stall conditions, the number of stall cells calculated by the transition model increases, while the stall frequency decreases. The microscopic flow structure calculated by the transition model and its relationship with the hump of the centrifugal pump head is obtained. The laminar separation bubbles near the blade leading edge will increase as the flow rate decreases, causing an increase in the friction loss on the blade surface, which lead to a hump in the pump head characteristics. The dynamic mode decomposition (DMD) method is used to extract the characteristic frequencies and corresponding modes of the 0.2Qd condition. In the high-order mode of the stall flow field with transition, a low-pressure zone formed at the head of the blade has a tendency to fall off from the wall, which shows the high-order motion characteristics of the stall vortex. The results could guide centrifugal pump design and operation.

Experimental Investigation of Centrifugal Pump Characteristics

The pumps are divided into two main groups as positive displacement namely volumetric pumps and dynamic i.e. centrifugal pumps. Volumetric pumps are generally used to transport hydraulic oils, while centrifugal pumps are used to transport clean or dirty water. Pumps are the tools that are used to move liquid fluids from one place to another in many areas like as cars, industry, construction sites, agriculture, and homes. Therefore, determination of the hydraulic pump’s characteristics under various working conditions, including manometric head, overall efficiency, specific speed, and net positive suction head, is crucial for development, operational limitations, and durability. Experimental investigation is a more realistic method, although it is possible to determine the hydraulic pump characteristics by means of mathematical methods. Therefore, an experimental investigation is performed for the determination of the centrifugal pump characteristics in this study by using an experimental setup. The findings indicate that the hydraulic power given to the water and the electrical power used by the pump both increase up to a particular flow rate and then decline. Additionally, it is found that manometric head of the pump falls even as the overall flow losses rise as the flow rate rises. On the other hand, overall efficiency of the pump enhances at the specific flow rate and then it reduces with the increased flow rate while specific speed of the pump varies about linearly. Moreover, it is finally noticed that the tested centrifugal pump works in cavitations at all flow rates.