Stage Impeller Research Articles

Effect of an Inducer-Type Guide Vane on Hydraulic Losses at the Inter-Stage Flow Passage of a Multistage Centrifugal Pump

A multistage centrifugal pump was developed for high head and high flow rate applications. A double-suction impeller and a twin-volute were installed at the first stage followed by an impeller, diffuser and return vanes for the next four stages. An initial design feasibility study was conducted using three-dimensional computational fluid dynamics tools to study the performance and the hydraulic losses associated with the design. Substantial losses in head and efficiency were observed at the interface between the first stage volute and the second stage impeller. An inducer-type guide vane (ITGV) was installed at this location to mitigate the losses by reducing the circumferential velocity of the fluid exiting the volute. The ITGV regulated the pre-swirl of the fluid entering the second stage impeller. The pump with and without ITGV is compared at the design flow rate. The pump with ITGV increased the stage head by 63.28% and stage efficiency by 47.17% at the second stage. As a result, the overall performance of the pump increased by 5.78% and 3.94% in head and efficiency, respectively, at the design point. The ITGV has a significant impact on decreasing losses at both design and off-design conditions. An in-depth flow dynamic analysis at the inducer-impeller interface is also presented.

Multistage pump axial force control and hydraulic performance optimization based on response surface methodology

In order to comprehensively optimize the axial force and hydraulic performance of the multistage pump, considering that there are relatively more secondary impeller stages and the blade profile has a greater impact on the axial force and hydraulic performance, Plackett–Burman test design method in this paper is adopted to conduct significance analysis and screening of the secondary impeller parameters. Based on the response surface methodology, a central composite test is designed for three control variables with strong sensitivity. The multiple regression model between the parameters of the secondary impeller and the hydraulic performance and axial force of the multistage pump is established. The optimal parameter combination which takes the performance and axial force into account is obtained. The accuracy of the optimization results is verified through tests. The results show that the blade exit angle, outlet diameter and blade wrap angle of the secondary impeller have the most significant influence on the axial force and hydraulic performance of the multistage pump. The results of variance analysis and coefficient test show that the regression model is highly significant and can reflect the objective relationship between the control parameters of the secondary impeller shape and the response objectives. A larger outlet diameter and blade wrap angle of the secondary impeller can improve the head of the multistage pump. A larger blade wrap angle and a smaller blade exit angle of the secondary impeller can reduce the axial force of the multistage pump. By solving the multiple regression equation, it is found that when the outlet diameter of the secondary impeller is 292 mm, the blade exit angle is 22°, and the blade wrap angle is 150°, the axial force of the multistage pump is the lowest and the hydraulic performance is slightly improved. It is verified by experiments that the head and efficiency of the optimized multistage pump increase by 0.95% and 1.71%, respectively, the temperature of the front and rear bearings decreases by 16.49% and 16.17%, respectively, and the vibration speed of the multistage pump along three directions is significantly reduced.

Prospects for production of viscous fluid by electric shaft-driven vane pumps (ESP)

The article deals with the prospects of developing significant world reserves of high-viscosity oil. Its production requires specific equipment and technologies, selection of efficient equipment, as well as a special approach in its operation. At the same time it is necessary to take into account the influence of high viscosity on the main characteristics of pumps and on the operating conditions of the equipment in the well. The reasons for unstable operation of the ESP at start-up after long stops are described. The methods of recalculation of characteristics of pumps for oil production of common design are offered. Some results of researches of such pumps on viscous liquid and recommendations on calculation of a flowing part are provided. The possibilities of pumps with open impeller stages and with increased shaft speeds are determined. Additional reasons for decreasing the characteristics of the pump on the viscous fluid, results of the test of stage assembly with measurement of average circumferential components of flow rates at different viscosity of the pumped fluid are given. The possibility of using helico-axial pumps is also considered. Application of modern programs and methods of equipment selection and operation, ESP rotor speed regulation, liquid temperature regulation in tubing and automation of the whole oil production process is recommended. Possible design changes of the ESP in the process of tubing production for the purpose of increasing their efficiency in comparison with the serial pumps are specified. The article can be useful for specialists in design, selection and operation of equipment for high-viscosity oil production.

Hydraulic Optimization of Two-Way Counter-rotating Axial Flow Pump Turbine

The two-way counter-rotation technology is mainly applied to the tidal power station. In this paper, the hydrodynamic optimization of the two-way counter-rotating axial-flow pump turbine is carried out. Under the premise of realizing the forward and reverse power generation and the forward and negative pumping basic function, it has important engineering significance and academic value for improving the pump turbine performance of various working conditions. The main contents are as follows: hydraulic design of “S”-shaped blade for the two-way counter-rotating axial-flow pump turbine is conducted, and the influence of the gap between different impeller stages on the performance is calculated and analyzed, and the variation law of head and efficiency of the pump turbine under different inter-stage clearances is obtained. And the influence of the inter-stage gap on the unit is summarized from the vorticity distribution and the axial section pressure cloud diagram analysis, and the range of the best inter-stage gap of the unit performance is determined.

Research on the Pump Shaft Stability Analysis of Multistage Centrifugal Pump During Closed-Valve Start-Up Process

In order to analyze the pump shaft stability of multistage centrifugal pump during the closed-valve start-up process, the transient internal fluid field and structural field during the closed-valve start-up process of the TDM 35-140×13 segmental multistage centrifugal pump are solved by transient fluid-solid coupling. The transient deformation and vibration velocity of the pump shaft are analyzed. It is found that the maximum deformation amount of the third stage impeller and the pump shaft cylindrical contact surface (N=7 node area) during the whole closed-valve transition start-up process is the largest. The maximum deformation in the region where the nodes 1≤N≤10 are significantly greater than that in other regions. In the 11≤N≤19 node, with the node position coordinate value N increasing, the maximum deformation amount is continuously decreasing. During the entire closed-valve transition start-up process, the vibration speed of the pump shaft fluctuates drastically. In the node of 1≤N≤19, with the node position coordinate value N increasing, the maximum vibration velocity first increases and then decreases. The maximum vibration speed at N=11 nodes is higher than that of all other nodes.

Effect of Balance Drum Clearance on the Flow in the last stage Impeller Back Sidewall gap

Effect of Balance Drum Clearance on the Flow in the last stage Impeller Back Sidewall gap

Effect of Diversion Cavity Geometry on the Performance of Gas-Liquid Two-Phase Mixed Transport Pump

For the purpose of improving the transport capability of the mixed transport pump, a new self-made three-stage deep-sea multiphase pump was taken as the research object. Based on the Euler-Euler heterogeneous flow model, liquid (water) and gas (air) are used as the mixed media to study the external characteristics and internal flow identities of the mixed pump under different gas volume fraction (GVF) conditions. According to the simulation results, a local optimal design scheme of the diversion cavity in the dynamic and static connection section is proposed. The numerical results before and after the optimization are compared and analyzed to explore the effect of the diversion cavity optimization on the performance, blade load and internal flow identities of the pump. The results show that the head and efficiency are obviously improved when the inner wall of the diversion cavity is reduced by 4 mm along the radial direction. After optimization, under the condition of 10% gas content, the head and efficiency is increased by 3.73% and 2.91% respectively. Meanwhile, the hydraulic losses of the diversion cavity and diffuser are reduced by 9.11% and 4.32% respectively. The gas distribution in the impeller is improved obviously and the phenomenon of a large amount of gas phase accumulation is eliminated in the channel. In addition, the abnormal pressure load on the blade surface is eliminated and the turbulent flow energy intensity is reduced. The average turbulent kinetic energy ( T K ) at i = 0.51 of the first stage impeller passage is reduced by 35%. Finally, the reliability of the numerical method is verified by the experimental results. To sum up, the performance and internal flow identities of the optimized mixed transport pump are improved, which verifies the availability and applicability of the optimization results. This provides a reference for the research and design of a multiphase mixed transport pump in the future.

Investigation of the influence of the angle of the installation of the blades of the impeller of the regenerative pump on its energy characteristics by the methods of hydrodynamic modeling

AnnotationThis paper focuses on the study of the influence of the vortex stage impeller blades angle installation in a centrifugal vortex pump. The mathematical model used in the numerical modeling is described. The 3 variants models of working regenerative impeller with different installation angles are considered. The paper shows the influence of the angle of the blades on the energy characteristics. The evaluation criteria were pressure, hydraulic efficiency and manufacturability. The results obtained during hydrodynamic modeling are presented in the form of velocity distribution vector fields. This paper will be of interest to specialists in the field of designing vortex hydraulic machines.

Numerical Investigation on Bubble Distribution of a Multistage Centrifugal Pump Based on a Population Balance Model

This work aimed to study the bubble distribution in a multiphase pump. A Euler-Euler inhomogeneous two-phase flow model coupled with a discrete particle population balance model (PBM) was used to simulate the whole flow channel of a three-stage gas-liquid two-phase centrifugal pump. Comparison of the computational fluid dynamic (CFD) simulation results with experimental data shows that the model can accurately predict the performance of the pump under various operating conditions. In addition, the liquid phase velocity distribution, gas-phase distribution, and pressure distribution of the second stage impeller at a 0.5 span of blade height under three typical working conditions were compared. Results show that the region with high local gas volume fraction (LGVF) mainly appears on the suction surface (SS) of the blade. With the increase in inlet gas volume fraction (IGVF), vortices and low velocity recirculation regions are generated at the impeller outlet and SS of the blade, the area with high LGVF increases, and gas–liquid separation occurs at the SS of the blade. The liquid phase flows out of the impeller at high velocity along the pressure surface of the blade, and the limited pressurization of fluid mainly happens at the impeller outlet. The average bubble size at the impeller outlet is the smallest while that at the impeller inlet is the largest. Under low IGVF conditions, bubbles tend to break into smaller ones, and the broken bubbles mainly concentrate at the blade pressure surface (PS) and the impeller outlet. Bubbles tend to coalesce into larger ones under high IGVF conditions. With the increase in IGVF, the bubble aggregation zone diffuses from the blade SS to the PS.

Erratum to: Effect of Balance Drum Clearance on the Flow in the last stage Impeller Back Sidewall gap

Erratum to: Effect of Balance Drum Clearance on the Flow in the last stage Impeller Back Sidewall gap

Visualization of two-phase gas-liquid flow in a radial centrifugal pump with a vaned diffuser

The operation of centrifugal pumps with gas-liquid mixtures is a common problem in the oil and gas industry. The main problem is related to the accumulation of gas inside the Electric Submersible Pump (ESP) impellers, which causes degradation of the pump pressure-rise. Literature about global performance parameters of centrifugal pumps operating with gas-liquid flows is limited, and studies focused on understanding the complex flow patterns occurring inside impellers are even scarcer. In this scenario, this work presents an experimental work developed to carry out, simultaneously, head evaluation and high-speed flow visualization in a two-stage centrifugal pump with radial-type impellers and a vaned diffuser. The pump casing and the first stage impeller were replaced by equivalent pieces reproduced with great fidelity using a transparent material in order to allow flow visualization while minimizing the effect of non-original pump parts on performance. Results show flow pattern transitions in the impeller channels when the rotating speed, the inlet gas flow rate and the liquid flow rate are changed, whereas only a single flow pattern was observed in the diffuser for the whole range of tested operating conditions. In addition, increasing the rotating speed causes, in general, a decrease of the bubble diameters inside the impeller, improving the pump's ability to handle higher gas flow rates and ultimately extending the operational window of the pump. This analysis can provide a source of data that can be useful to support theoretical models or to validate numerical simulations.

Numerical investigationof clocking effect of impellerson a multistage pump

Purpose The purpose of this paper is to investigate the clocking effect of impellers and the superposition between pump stages caused by clocking effect in a five-stage centrifugal pump. Then the best clocking scheme in terms of vibration is tried to be provided as well. Design/methodology/approach All curves of pressure fluctuation in different impeller stages can be divided into two groups for the difference of 1/16 T in time domain. The difference is mostly in vibration frequency and amplitude, little in pump head and efficiency. Findings All curves of pressure fluctuation in different impeller stages can be divided into two groups for the difference of 1/16 T in time domain. The difference is mostly in vibration frequency and amplitude, little in pump head and efficiency. Research limitations/implications This research involves eight different impeller clocking schemes. The results show that the clocking effect has little influence in pump head and efficiency, but the influence in pressure fluctuation is larger. Practical implications The paper provides guidance for the design of multistage pump for better vibration performance. Originality/value This research involves eight different impeller clocking schemes, the results show that the clocking effect has little influence in pump head and efficiency, but the influence in pressure fluctuation is larger. Then the best clocking scheme In terms of vibration is tried to be provided through analysis.

Аэродинамическое совершенствование рабочих колес центробежных компрессорных ступеней

Аэродинамическое совершенствование рабочих колес центробежных компрессорных ступеней

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

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

Profit Increase With New Subsea Boosting Products

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 27747, “Profit Increase With New Subsea Boosting Products,” by åge Hofstad and Hans Christian Nilsen, Aker Solutions, prepared for the 2017 Offshore Technology Conference, Houston, 1–4 May. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission. Emphasis on identifying more-efficient subsea boosting solutions has led to a number of initiatives in the industry. A new multiphase-pump technology has been developed that will expand the operation envelope for subsea boosting and create better opportunities for more-effective offshore-field development. A parallel, and equally important, advance has been the development of a new heavy-duty 6-MW subsea motor. Introduction In 2011, a decision was made to abandon twin-screw technology because of the low sand-handling resistance and limited differential-pressure generation with multiphase fluids that these pumps had demonstrated during in-house testing. Thus, a development project was initiated. Multiphase-Pump-Development Project For this development project, the main target was to increase pump performance in the following ways: From 4,000 to 6,000 rev/min From 3 to 6 MW From 500 to 1,000 actual m3/h From 50- to 150-bar differential pressure at 70% gas-volume fraction (GVF) Reaching these targets would require design of a new motor to operate at higher speeds at twice the power. Multiphase-Pump Technology It was evident from recent experience that the pump design had to use the rotodynamic principle (dynamic energy transfer to the liquid) and not the positive-displacement principle. Before this multiphase-pump development, a hybrid multiphase pump with both multiphase impellers and radial impellers had shown very good test results when operating with multiphase fluids. The multiphase impeller design has commonly been a helicoaxial design, which has been the standard until now. However, on the basis of previous experience and tests, a different technology was chosen. This was a mixed-flow impeller in which the flow channel was partly axial and partly radial. This design uses centrifugal action to provide more pressure generation from each impeller. This principle can be termed a helico-mixed-flow design. Multiphase-Pump-Prediction Model From promising initial pilot pump tests, the authors were able to prepare a prediction model for the multiphase pump. The prediction model is, in itself, a challenging piece of work because the fluid conditions will change considerably through the pump. It is necessary to use a stepwise approach and calculate the fluid parameters for each impeller stage.

Radial force within two-stage axial-flow blood pump based on LES

Radial force in implantable two-stage axial flow blood pump (Artificial Heart) is a major factor affecting the operation stability. In order to investigate the transient operation characteristics of two-stage blood pumps, three-dimensional, unsteady numerical simulations were conducted by using the large eddy simulation (LES) model, PISO algorithm based on the sliding mesh technique in Fluent. The performance of the pump was obtained and compared with the experimental results. Besides, the radial force at various monitoring points were acquired; next, they were analyzed in time and frequency domains, respectively. It was demonstrated that the radial force at all the monitoring points changes periodically with time, its number of periods is identical to the number of blades but less affected by the number of guide vane blades, its frequency is close to the blade passing frequency. The frequency of radial force within the impeller increases gradually towards the impeller outlet and approaches the maximum value there, while the variation tendency of the frequency is opposite within the guide vane. The mostly dramatic radial force occurs at the impeller outlet, the main frequency at various monitoring points is almost equal to the impeller passing frequency. The amplitude of radial force coefficient at the monitoring points in the second stage impeller is higher than the first stage impeller. Additionally, the main frequency of radial force in the first stage impeller is different from the second stage guide vane.

Effect of blade tip pattern on performance of a twin-stage variable-pitch axial fan

The effect of five blade tip patterns on performance and acoustics of a twin-stage variable-pitch axial fan is investigated numerically. The best tip pattern is determined by comparing the overall performance under the condition of those patterns carving in stage I impeller, and the performance promotion is then examined under the selected tip grooving in stage I impeller, stage II impeller and both two stage impellers. Finally, flow dynamics and acoustic noise are explored. The results show that all proposed tip patterns can improve fan performance effectively, and the best scenario is the direct groove tip implementing in stage I impeller. After blade tip grooving, the internal dynamics in the tip clearance tends to be more complex, the static pressure reduces notably in the suction side and the sound power level in the tip increases significantly, while the leakage losses decline distinctly. Blade tip pattern changes the profile and amplitude of the sound pressure in time domain; the base frequency and first five−order harmonics are clearly observed in two stage impellers, but only the second−order harmonics are emerged in the other regions. The noise is generated largely by low and medium frequency sound with an obvious broadband feature.

초저온 산업용 액중펌프 임펠러 설계에 관한 연구

The purpose of this study is to examine the basic design of a submerged cryogenic pump, which is a two stage impeller pump. We limited this study to the impeller design of the submerged pump. We calculated its velocity triangle based on the impeller blade configuration and, in order to check its natural frequency, we carried out a modal test using a finite element method (FEM) analysis. Basically, modal test results had quite similar to FEM analysis.

Noise source identification and noise reduction in a multi-state, centrifugal air compressor system

The objective of this research is to recommend practical noise control schemes for Hanwha Techwin’s multi-stage, centrifugal air compressors. For purpose of achieving this objective, far- and near-field noise measurements, sound intensity measurements, and structural vibration measurements were performed first to identify the acoustic characteristics of a compressor. Through these measurements, it was shown that the most dominant noise and vibration components were at the blade passing frequencies (BPFs) of the compression stage impellers. Thus, by suppressing these tonal BPF noise components, the overall noise level was reduced effectively. Here, Helmholtz resonators, dynamic dampers, noise insulation materials, and an enclosure were recommended to reduce these tonal noise components. The Helmholtz resonators could be used to reduce the overall SPL up to 3.5 dBA. By applying the mass dampers, 2.7 dBA reduction at 7 kHz and 1.5 dBA reduction at 10 kHz could be achieved. The installation of the sound insul...

The research and test of the cavitation performance of first stage impeller of centrifugal charging pump in nuclear power stations

The safety production is the most important index for nuclear power development, and the CVCS (chemical and volume control system) occupies an important place in safety control system. The CCP (centrifugal charging pump) is an important component of CVCS system and its particularity decides the high requirements on the cavitation performance, so the research on CCP cavitation has great significance. Using the 3D Pro/E software, the paper makes models of the flow passage components of first stage prototype of CCP in nuclear power stations, and completes the cavitation steady-state computation in the case that the high flow rate of first stage prototype reaches Q=160m3/h using the numerical computation software ANSYS CFX. The cavitation is divided into the following five stages according to its development process: inception operating condition, development operating condition, critical operating condition, serious operating condition and fracture operating condition. The research analyze the flow field, static pressure fields and bubble distribution conditions in the impeller in different cavitation states, and selects the middle flow line, the front shroud flow line and the back shroud flow line from the same blade for the comparative analysis; to verify the reliability of computation, the researcher made a first stage cavitation prototype to verify its hydraulic performance and cavitation performance. After the comparative analysis on the flow field, pressure and bubble distribution conditions of CCP first stage impeller in different cavitation states, the research draws the following conclusions: (1) as the inlet pressure decreases, the cavitation degree increases, the bubble distribution area extends from impeller inlet to impeller outlet and shows different laws in different cavitation states; (2) the generation of cavitation is affected by the pressure changes in impeller passages, and when the inlet pressure decreases, the static pressure in impeller passage decreases, thus producing a local low-pressure area; (3) the comparison of computation and test results shows small errors, thus proving the accuracy of analog computation; besides, the research verifies the cavitation performance in different flow rates by test, and test results show that NPSH3 is smaller than the 7.8m stipulated in Technical Specifications in any flow rate condition, indicating that the design is reasonable. The research points out a direction for the further improvement of optimization design of CCP cavitation performance.