Characteristics Of Centrifugal Pump Research Articles

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.

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.

Numerical study on cavitation flow and induced pressure fluctuation characteristics of centrifugal pump

In order to reveal the variation law between cavitation process and pressure pulsation characteristics of centrifugal pump, the internal flow characteristics and pressure pulsation characteristics of centrifugal pump during cavitation development are studied in this paper. First, select the standard k- ε with good coincidence between external characteristics and test data under rated conditions model for calculation after compare the standard k- ε, RNG k- ε and SST k- ω. Then, based on the unsteady calculation results, the characteristics of the internal flow before and after the cavitation critical point, the frequency domain characteristics of the pressure pulsation on the volute wall and at the impeller inlet monitoring points in different cavitation stages are compared and analyzed. Finally, root mean square (RMS) is used to study the change trend of pressure fluctuation energy intensity with cavitation process. The research results show that the prediction accuracy of the characteristic points of RMS change curve of pressure fluctuation for cavitation is higher than that of the traditional 3% head drop point. Using the energy characteristics of pressure fluctuation can more accurately and timely determine the occurrence of cavitation.

Predicting Centrifugal Pumps’ Complete Characteristics Using Machine Learning

The complete characteristics of centrifugal pumps are crucial for the modeling of hydraulic transient phenomena occurring in pipe systems. However, due to the effort required to obtain these curves, pump manufacturers typically only provide basic information, particularly when the pump operates under normal conditions. To acquire the full characteristic curves based on the manufacturer’s normal performance curve, a machine learning (ML) model is proposed to predict full, complete Suter curves using a pump’s specific speed with the known parts of the Suter curve. The training data for the model are sourced from the available Suter curves from laboratory experiments. Subsequently, the proposed ML model combines several types of regression models in an attempt to find the most accurate prediction in terms of the root mean square error (RMSE). The result proved highly efficient, as the experiments attained a maximum RMSE value of 0.032 across the three categories of centrifugal pumps based on their specific speeds, hence demonstrating the potential of machine learning in the study of pump characteristic curves.

Assessment of cavitation noise in a centrifugal pump using acoustic finite element method and spherical cavity radiation theory

To examine the cavitation noise characteristics of centrifugal pumps, the combination of test and simulation was applied in this study. The numerical method is based on spherical cavity radiation theory and the acoustic finite element method. A multi-field synchronized test-rig was built to study and validate the numerical results under cavitating flow and cavitation noise conditions. The three-dimensional unsteady flow-field simulation was carried out inside the centrifugal pump based on DES and the improved-RZGB cavitation model. The constructed numerical method for cavitation noise was used to solve the acoustic-field based on the flow-field solutions. The test–simulation comparison reveal that the numerical simulation results are consistent and reliable. The development of cavitation has a stronger influence on the strong vorticity regions in the impeller flow channel, and the vortex has a promotional-effect on the formation of cavitation. With the same cavitation number, the acoustic-power on the blade suction-side is greater than the pressure-side of the blade. As the cavitation number decreases, the pulsating radiated noise of cavitation volume is the primary noise-source for the increased acoustic-power value. At this stage, the SPL and total SPL at the model pump inlet show a decreasing trend during the severe cavitation-stage.

Numerical Simulation of Cavitation Characteristics of a Centrifugal Pump Based on an Improved ZGB Model

We modified the Zwart–Gerber–Belamri (ZGB) cavitation and RNG turbulence models based on their rotational motion characteristics, as well as simulating the phenomenon of small fluctuations in rotational speed due to the action of hydraulic excitation force, to increase the precision of numerical simulations of the cavitation characteristics of centrifugal pumps. According to the theory behind the enhanced model, the pressure gradient in the impeller runner changes uniformly, and the cavitation bubble initially manifests itself at the front edge of the blade’s suction. With the reduction in the effective margin, changes in the impeller flow channel’s pressure gradient increased, the blade’s suction-side cavitation area expanded, and the flow field’s internal disturbance enhanced, resulting in hydraulic loss to the centrifugal pump, considerably reduced operating performance, and the blade pressure side by the cavitation-affected area becoming smaller. The blade’s suction-surface pressure–load curve can be divided into a low-pressure cavitation zone, a pressure fluctuation zone, and a pressure stabilization zone. The pressure–frequency-domain diagram of each monitoring point has a discrete distribution, and the main frequency is the blade-passing frequency ƒ = 293 Hz and its n times frequency. With the deepening of the cavitation, the amplitude of the main frequency in the low-frequency band showed a trend of increasing and then decreasing, and the amplitude of the high-frequency band showed an increasing trend. When we applied the ZGB cavitation model based on the improved rotational motion characteristics to our numerical calculation of the centrifugal pumps’ cavitation characteristics, our calculated cavitation performance curve was closer to the experimental value than the ZGB model, and when the centrifugal pump’s cavitation degree was increased, the area covered by the vacuole area was 1/4 of the suction side of the vane.

Investigation of gas bubble coalescence suppression and its effect on the operation of a booster pump as part of a pump-ejector system when pumping water-gas mixtures

Article presents an overview of studies of the gas bubbles interaction processes in the composition of water-gas mixtures. Data are given on theories that indirectly indicate the nature of the phenomenon of coalescence, or its suppression. It has been established that there are rational ranges of parameter values at which coalescence suppression is observed, however, when some critical values of these parameters are exceeded, the coalescence suppression regime breaks down. The experimental studies of the gas flow rate effect, passed in the bubbles flow form through a column with liquid, at various pressures and salinity of the liquid showed that an increase in the maximum gas flow rate with suppressed coalescence is observed in a certain range of salinity (with increasing pressure). However, further with an increase in salinity, the maximum the gas flow rate remains constant, after which the regime breaks. The addition of foaming surfactants increases the maximum gas flow rate. At the same time, a study of multistage centrifugal pump characteristics showed that the addition of surfactants improves the performance of the pump up to a certain concentration, with an increase in this concentration, the performance improves slightly. A further direction of studying the technology of creating stable water-gas mixtures is also formulated. Keywords: carbon footprint reduction; SWAG technology; pump-ejector systems; water-gas mixture; coalescence of gas bubbles.

Investigation on Stall Characteristics of Centrifugal Pump with Guide Vanes

Stall usually occurs in the hump area of the head curve, which will block the channel and aggravate the pump vibration. For centrifugal pumps with guide vanes usually have a clocking effect, the stall characteristic at different clocking positions should be focused. In this paper, the flow field of the centrifugal pump under stall conditions is numerically simulated, and the rotor–stator interaction effects of the centrifugal pump under stall conditions are studied. The double-hump characteristic is found in the head curve by using SAS (Scale Adaptive Simulation) model. The hump area close to the optimal working condition is caused by hydraulic loss, while the hump area far away from the optimal working condition point is caused by the combined action of Euler’s head and hydraulic loss. The SAS model can accurately calculate the wall friction loss, thus predicting the double-hump phenomenon. The pressure fluctuation and head characteristics at different clocking positions under stall conditions are obtained. It is found that when the guide vanes outlet in line with the volute tongue, the corresponding head is the highest, and the pressure fluctuation is the lowest. The mechanism of the clocking effect in the centrifugal pump with guide vanes is obtained by simplifying the hydrofoil. It is found that when the downstream hydrofoil leading edge is always interfered with by the upstream hydrofoil wake, the wake with low energy mixes the boundary layer with low energy, which causes small-pressure pulsation. The results could be used for the operation of centrifugal pumps with guide vanes.

Force Characteristics of Centrifugal Pump as Turbine during Start-Up Process under Gas–Liquid Two-Phase Conditions

The start-up process of a centrifugal pump as turbine (PAT) under gas–liquid two-phase conditions was simulated based on Fluent, and the evolution mechanism of the internal flow field and the variation law of force characteristics were studied in its start-up process under gas–liquid two-phase conditions. The results show that the area with high gas phase concentration corresponds to a strong vortex at the beginning of the start-up. The vortex intensity in the impeller gradually decreases with an increase in rotational speed. The gas volume fraction of the blade suction surface is more significant than that of the blade pressure surface. The higher the inlet gas volume fraction (IGVF) is, the more severely the blade load will fluctuate during the start-up process. As the rotational speed increases, the fluctuation of the blade load gradually weakens, and the maximum load is distributed near the inner edge of the blade after the rotational speed is stable. The periodic unbalanced radial force is produced in the start-up process. From the pure liquid conditions to the gas–liquid two-phase conditions with increasing IGVF, the dominant frequency amplitude of radial force shows a similar trend of decreasing first but then increasing. After the rotational speed tends to be stable, the dominant frequency of radial force is equal to the rotational frequency of the blade. With the increase in rotational speed, the dominant frequency amplitude of axial force decreases gradually. The higher the IGVF, the greater the dominant frequency amplitude of axial force at the same time.

ANALISIS UNJUK KERJA POMPA SENTRIFUGAL DENGAN PEMASANGAN INDUCER PADA LOCK NUT IMPELLER

Pompa sentrifugal merupakan mesin fluida yang paling banyak kita gunakan dalam kehidupan seharihari. Dalam pengoperasiannya terdapat banyak kerugian yang ditimbulkan oleh instalasi maupun konstruksi pompa itu sendiri. Telah banyak penelitian yang dilakukan untuk meminimalkan kerugiankerugian tersebut termasuk penelitian yang kami lakukan yaitu berupa modifikasi pada bagian inlet pompa sentrifugal. Penelitian ini bertujuan untuk mengetahui pengaruh pemasangan induser pada locknut impeller terhadap karakteristik pompa sentrifugal tipe aliran radial. Disini yang dimaksud dengan karakteristik pompa adalah head, debit, dan efisiensi pompa. Metode yang digunakan adalah eksperimen. Kegiatan yang dilaksanakan pada penelitian ini meliputi: perancangan dan perakitan alat pengujian pompa sederhana, pembuatan spesimen, pengambilan data, analisis dan pembahasan serta kesimpulan. Pada penelitian ini terdapat empat jenis pengujian, yakni: 1) Pompa sentrifugal tanpa modifikasi (normal); 2) Pompa modifikasi ke-1 dengan induser, panjang 25 mm; 3) Pompa modifikasi ke2 dengan induser, panjang 50 mm; dan 4) Pompa modifikasi ke-3 dengan induser, panjang 75 mm. Penelitian menunjukkan bahwa modifikasi dapat memperbaiki karakteristik pompa sentrifugal yang menjadi objek penelitian dimana terjadi peningkatan head total (Htot), debit (Q) dan efisiensi (ηp). Karakteristik terbaik yang diperoleh pada pompa modifikasi ke-2 dengan induser panjang 50 mm, disusuloleh pompa modifikasi ke-3 dengan induser panjang 75 mm, pompa modifikasi ke-1 dengan induser panjang 25 mm dan yang terendah adalah pompa tanpa modifikasi (normal). Karakteristik pompa sentrifugal Peningkatan tersebut disebabkan karena modifikasi dapat meminimalkan gejala pra-rotasi, turbulensi, serta pemisahan aliran. Atau dengan kata lain modifikasi menyebabkan terjadinya perbaikan pola aliran pada bagian inlet pompa sentrifugal.