Volute Pump Research Articles

Co-creation of affordable and clean pumped irrigation for smallholders: lessons from Nepal and Malawi

Abstract Pumped irrigation is a way to intensify smallholder production. In this context, the Dutch company aQysta has developed the Barsha pump (BP), the first-ever commercial version of the spiral pumps. BPs, however, face several constraints that affect the decision-making and access of smallholders to this and other agricultural technologies, and thus to their benefits. On this subject, Product Service System (PSS) is a type of business model able to potentially cope with a number of restrictions of different nature. Moreover, if co-created with the feedback of the users, and by addressing contextual tensions of different cases, these models can be substantially richer than their top-down counterparts. Six cases of the use of BPs have been addressed in Nepal and Malawi. Both primary and secondary data, analyzed qualitatively under the analytic induction approach, were collected through unstructured interviews and Q-methodology. Evidence shows a wide range of (non-)technical facilitating and hampering conditions for the BP, as well as preferences of the smallholders in regard to existing and proposed business model elements. Based on the corresponding analysis, a set of opportunities for an improved BP-based business model – PSS, aiming to fulfil several (and at times opposing) needs, is ultimately proposed in the current paper.

Geometrical effects on performance and inner flow characteristics of a pump-as-turbine: A review

A pump-as-turbine is a hydraulic machine that can operate as a pump and turbine at the same time. Pump-as-turbine happens to be the most appropriate method for meeting the world’s energy demands, particularly in rural and isolated areas of a country. Furthermore, the operating cost of microhydropower systems is lower compared to conventional hydrodynamic turbines, but it requires high initial investment. Pump-as-turbine has been applied in many engineering fields such as irrigation, sewage, reverse osmosis, water distribution systems, farms, small pump storage power house, and pressure dropping valves. However, pump-as-turbine operates inefficiently at part-load due to lack of flow control device. In addition, the pump generates high flow instabilities in pump-as-turbine mode due to the shift of the best efficiency point toward higher head and discharge. This study extensively discusses the flow mechanism, modifications, and flow instabilities in the pump-as-turbine mode operation. First, the mechanism of the pump-as-turbine can be described as drawing out mechanical energy from the flow in the reverse mode. Since the energy drawn mainly depends on the major hydraulic components of the pump (impeller and volute), many studies have been conducted on the impeller and volute. It can be concluded that high amount of hydraulic losses is generated in pump-as-turbine mode operation. This can partly be attributed to the fixed geometrical parameters such as the stationary volute. To increase the usage of pump-as-turbine, it is very crucial to predict their performance in advance before manufacturing, which requires the understanding of the flow behavior as a result of geometrical parameters. In order to improve the energy conversion and understand the flow behavior in the centrifugal pump functioning as pump-as-turbine, the key geometrical parameters should be carefully designed. The designs of the main geometrical parameters do affect not only the hydraulic performance of pump-as-turbine but also the operational instability. The operational instability of hydraulic machines mainly depends on the pressure and the velocity fluctuation intensity generated within the flow passage as a result of the impeller–volute interaction. The magnitudes of the instabilities have the tendency to cause noise, vibration, harshness, and cavitation which reduces the life span of the hydraulic machine. Moreover, appropriate selection of the pump and unavailability of pump data contribute to the challenges faced. Finally, this review proposes specific solutions in terms of geometrical modifications and improvement of the computational design methods to handle the hydraulic losses faced during the pump operation; thus, this study can serve as a point of reference for a pump-as-turbine performance optimization.

Simulation of a Radial Pump Fast Startup and Analysis of the Loop Response Using a Transient 1D Mean Stream Line Based Model

A predictive transient two-phase flow rotodynamic pump model has been developed in the Code for Analysis of THermalhydraulics during an Accident of Reactor and safety Evaluation (CATHARE-3). Flow inside parts of the pump (suction, impeller, diffuser and volute) is computed according to a one-dimensional discretisation following a mean flow path. Transient governing equations of the model are solved using an implicit resolution method and integrated along the curvilinear abscissa of the element. This model has been previously qualified at the component scale by comparison to an existing experimental database. The present study aims at extending the validation at the system scale: a whole experimental test loop is modelled. The ability of the transient pump model to predict flow rate, head and torque as a function of time during a 1-s pump fast start-up is evaluated. The transient evolution of the pressure upstream and downstream from the centrifugal pump is well predicted by the simulation compared to the measurements. Local quantities such as pressure and velocity inside elements of the circuit are analysed. In the considered case, inertial effects of the global circuit are dominant when compared to pump inertial effects due to the high characteristic lengths of the pipes. The main perspective of this work consists in the simulation of similar pump transients, in cavitating conditions.

Development and Numerical Performance Analysis of a Pump Directly Driven by a Hydrokinetic Turbine

Marine and hydrokinetics (MHK) represent an emerging industry with hundreds of potentially viable technologies, such as potential extractable energy from plain area rivers where the water level differences are very small and the traditional water turbine pump (WTP) cannot be used. A suitable WTP, composed of a tubular turbine directly driving a centrifugal pump, was designed and developed based on computational fluid dynamics (CFD) and model tests. Two general design schemes of such river-current (RC)-driven WTP are presented here, obtaining the desired operating parameters of discharge and pump head. A CFD analysis of Scheme B, which employs a radial outlet, allowing additional degrees of freedom for the dimensions of the centrifugal pump, was carried out and verified experimentally by model tests. The minimum deviation of pump head is within ±5%, and the trend of other working conditions is consistent, so the results of the numerical simulation and model tests show good agreement, demonstrating the feasibility of the CFD method for practical applications. Then, using the CFD method, the optimum rotational speed for the turbine was determined, and the turbine draft tube was improved further. With a turbine runner diameter of 0.5 m, the results show best performance at n = 350 r/min. The straight conical draft tube was changed to an elbow draft tube with multiple exits. Additionally, four different cross-sectional shapes were designed for the pump volute, and their effects on the performance of the WTP were analyzed. Finally, the round shape was selected, because of its best performance. The turbine unit has the highest efficiency of 81.2%, at an inlet velocity v = 2.4 m/s, while the pump exhibits the best efficiency of 90.2% at the design discharge and head of 30 l/s and 4.45 m respectively. Overall, the RC-driven WTP makes good use of the kinetic energy of the river current as a power source, solving the inapplicability of traditional WTP in plain areas.

Centrifugal pump impeller and volute shape optimization via combined NUMECA, genetic algorithm, and back propagation neural network

This paper presents a fast, efficient, and convenient shape optimization design method for the centrifugal pump impeller and volute. A meridional curve, stream surface, blade stacking, and two-dimensional blade profile are obtained for impeller parameterized fitting by NUMECA, which substantially decreases the parameters to be optimized. A combination of genetic algorithm (GA) and back propagation neural network (BPNN) is then employed to optimize the impeller design while preventing prematurity or stagnation due to the GA. The head and efficiency of the optimized impeller under the designed flow rate condition increase by 7.69% and 4.74%, respectively, while power decreases by 2.56% post-optimization. Static pressure in the optimized impeller middle span is more uniform post-optimization, and the hydraulic performance of the centrifugal pump with the optimized impeller exceeds that of the original centrifugal pump under low and designed flow rate conditions. Head increases by 2.69 m and efficiency increases by 4.32% under the designed flow rate condition as well. The base circle diameter, volute inlet width, and volute baffle tongue can be modified to optimize the volute shape design. The head of the centrifugal pump with the optimized volute and optimized impeller increases by 4.83 m and 6.35 m and efficiency increases by 9.12% and 18.65% under 1.2 and 1.4 times the designed flow rate compared to the pump with the original volute and optimized impeller. Vortices in the optimized volute are reduced significantly and particularly relative energy losses. Under low flow rate conditions, compared with the original centrifugal pump, the head and efficiency of the experimental centrifugal pump with optimized impeller and optimized volute increase by 1.56 m and 1.12%; under the designed flow rate condition, they increase by 4.34 m and 5.23%; and under the high flow rate condition, they increase by 3.71 m and 8.54%, respectively. Compared to the traditional optimization method, as evidenced by numerous shape optimization design cases, NUMECA-GA-BPNN produces better optimized shapes with stronger hydraulic performance more quickly and efficiently.

A Study on the Effects of Rotation Rate and Flow Rate on the Operating Characteristics in Centrifugal Pump

본 논문은 규정 유량, 양정, 회전수 및 비속도가 각각 0.7 ㎥/min, 8 m, 1750 rpm, 182 m, ㎥/min, rpm인 원심펌프의 운전시 펌프의 회전수와 유량의 변화가 펌프의 운전특성에 미치는 영향을 고찰하였다. 실험에 사용된 펌프는 안내깃이 없고 외주에 바로 접하여 와류실이 있는 볼류트 펌프를 회전수 1350 rpm에서 1750 rpm까지 100 rpm씩의 회전수 변화 5단계에 따른 H-Q특성, L-Q특성, η-Q특성 등의 관계와 무차원 성능 특성인 양정계수, 동력계수, 효율 등의 특성을 실험을 통하여 다음과 같은 결론을 얻었다. 회전수의 증가에 따라 펌프 성능의 변화정도를 추정할 수 있고, 펌프의 최대효율은 1450 rpm일 때 유량 0.165 ㎥/min, 양정 4.73 m에서 약 52%, 최대 회전수인 1750 rpm일 때 유량 0.183 ㎥/min, 양정 6.72 m에서 약 50%의 효율이 나타난다. 또한 양정 대 유량의 성능 특성 곡선상에서 등효율 곡선은 펌프의 상사법칙에 따른 원점을 지나는 2차식의 곡선으로 나타나지 않고 타원형으로 변형되어 나타난다. 마지막으로 유량계수가 증가함에 따라 동력계수는 증가하고 양정계수는 감소하며, 유량계수가 0.08일 때 최대효율 52% 되는 것을 통해 유량변화가 운전특성에 미치는 영향을 알 수 있다.This study examined effects of the operating characteristics of a pump according to the rotational speed of a pump and the change in flow rate when a centrifugal pump operates under the following conditions: regulated flow rate, head, rotational speed, and specific speed of 0.7 m/min, 8 m, 1750 rpm, an 182 (m, m 3 /min, rpm), respectively. The pump in the experiment did not have a guide vane and was connected directly to the rim, so that the rotational speed of the volute pump in a spiral or volute casing increased by 100 rpm from 1350 to 1750 rpm. The result of the relationship between the H-Q, L-Q, and η-Q characteristics and the dimensionless performance characteristics, such as the head coefficient, power coefficient and efficiency were studied. The change in pump performance could be estimated depending on the increase in the number of revolutions. The maximum efficiency of the pump was 52% with 1450 rpm, 0.165 ㎥/min flux, and 4.73 m of lift. The efficiency reached 50% with a maximum of 1750 rpm, 0.183 ㎥/min of flux, and 6.72 m of lift. The efficiency curve on the performance characteristics of the lift versus flux curve became oval not a curve from a quadratic equation that passes through the starting point according to the similarity law of the pump. Finally, when the flux coefficient increased, the power coefficient increased and the lift coefficient decreased. When the flux coefficient was 0.08, the maximum efficiency was 52%. Therefore, the change in flux affects the driving characteristics.

Reduction of radial thrust by using triple-volute casing

Abstract A complete centrifugal pump is designed and manufactured. The volute is designed such that partition vanes could be added to change the number of volutes. Experiments were performed on single-, double-, triple-volute centrifugal pump at 500, 800, and 900 rpm for each case. The results reveal that the non-dimensional performance curves for the three pumps are identical. The efficiency is increased due to the presence of the partition vane. The use of multiple-volute reduces the radial thrust. This reduction is more significant as the operation departs the BEP. At shut off, where the problem is most critical, the use of two- and three-volute reduces the radial thrust by 54% and 72%, respectively, below the thrust of a single volute pump.

Study on Flow Characteristics in Volute of Centrifugal Pump Based on Dynamic Mode Decomposition

To investigate the unsteady flow characteristics and their influence mechanism in the volute of centrifugal pump, the Reynolds time-averaged N-S equation, RNG k-ε turbulence model, and structured grid technique are used to numerically analyze the transient flow-field characteristics inside the centrifugal pump volute. Based on the quantified parameters of flow field in the volute of centrifugal pump, the velocity mode contours and oscillation characteristics of the mid-span section of the volute of centrifugal pump are obtained by dynamic mode decomposition (DMD) for the nominal and low flow-rate condition. The research shows that the first-order average flow mode extracted by DMD is the dominant flow structure in the flow field of the volute. The second-order and third-order modes are the most important oscillation modes causing unsteady flow in the volute, and the characteristic frequency of the two modes is consistent with the blade passing frequency and the 2x blade passing frequency obtained by the fast Fourier transform (FFT). By reconstructing the internal flow field of the volute with the blade passing frequency for the nominal flow-rate condition, the periodic variation of the unsteady flow structure in the volute under this frequency is visually reproduced, which provides some ideas for the study of the unsteady structure in the internal flow field of centrifugal pumps.

Reduction of Radial Thrust by Using Triple-Volute Casing Centrifugal Pump

Radial thrust in a single volute centrifugal pump, which is a result of pressure variation in the volute casing, is investigated in order to avoid failures caused by this thrust force. Two ideas are introduced to avoid or to minimize this thrust force, the first is a double volute, and the second is a triple volute. A complete centrifugal pump design was manufactured. The volute was designed such that partition vanes could be added to change the number of volutes. Experiments were performed on single, double, triple volutes centrifugal pump at 500, 800, and 900 rpm for each case. The performances of the three pumps as seen on a non-dimensional plot, are nearly the same in the three casing types (Single, double and triple volutes). However, the values of the efficiency reveal an improvement associated with the presence of the volute(s)On the other hand, the use of multiple volutes reduced the radial thrust force. These reductions were pronounced as the departure from the BEP was increased. At shut off for instance, the radial thrusts for the double volutes and triple volutes were reduced by 55% and 70%, respectively, below the thrust of a single volute pump.

Multi-Objective Genetic Algorithm Assisted by an Artificial Neural Network Metamodel for Shape Optimization of a Centrifugal Blood Pump.

A centrifugal blood pump is a common type of the pump used as a left ventricular assist device (LVAD) in the medical industries. The reduction of the LVADs hemolysis level to reduce the blood damage is one of the major concerns in designing of such devices. Also, the enhancement of the LVADs efficiency to decrease the battery size is another design requirement. The blood damage critically depends on the state of the blood being pumped. Besides the blood state, the blood damage also depends on the pump impeller and volute geometries. In this research, a multi-objective optimization of a centrifugal blood pump is performed. A complete 3D-optimization platform is established for both impeller and volute of a centrifugal blood pump consisting of parametric modeling, automatic mesh generation, computational fluid dynamics (CFD) simulation, and optimization strategy. A vast number of cases with various impeller and volute shapes are numerically simulated. Three different metamodels are created using artificial neural networks (ANNs) in order to approximate the pump hydraulic efficiency, hemolysis index (HI), and pressure head. The inverse of the relative pressure head is defined as the first objective and the summation of relative hemolysis index and the inverse of the relative efficiency is assumed as the second objective. Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is used to find the Pareto Front. A set of optimal points is selected. Finally, for the physiological flow conditions, the optimum design that provides 11.9% HI reduction and 7.2% efficiency enhancement is selected.

Transient response and critical speed analysis of large vertical volute pump

The analytical investigation of the rotor dynamics system in large vertical volute pump is presented in this paper. The radial force imposed on impeller is a time-independent value which is extracted from the numerical simulation results. A three-dimensional finite element analysis of the pump rotor was performed to investigate the critical speed and mode shape. The transient response of the rotor dynamics is studied by analysing radial excitation force at variable flow conditions. In addition, the stiffness and damping of the bearings are calculated by Software ARMD. The result shows that the resonance of pump will not occur under design condition. The radial displacement of monitoring point at impeller presents periodic variation when the time-independent radial force is imposed on impeller.

A Study of operational stability on performance for simplified volute pump

A Study of operational stability on performance for simplified volute pump

The effect of wear ring clearance on flow field in the impeller sidewall gap and efficiency of a low specific speed centrifugal pump

In this paper, the flow in the impeller sidewall gap of a low specific speed centrifugal pump is analyzed to study the effect of wear ring clearance and the resultant through-flow on flow field in this cavity and investigate the overall efficiency of the pump. Centrifugal pumps are commonly subject to a reduction in the flow rate and volumetric efficiency due to abrasive liquids or working conditions, since the wear rings are progressively worn, the internal leakage flow is increased. In the new operating point, the overall efficiency of the pump cannot be predicted simply by using the pump characteristic curves. The flow field is simulated with the use of computational fluid dynamics and the three-dimensional full Navier–Stokes equations are solved using CFX software. In order to verify the numerical simulations, static pressure field in volute casing and pump performance curves are compared with the experimental measurements. The results show that, for the pump with minimum wear ring clearance, the disk friction efficiency is the strongest factor that impairs the overall efficiency. Therefore, when the ring clearance is enlarged more than three times, although volumetric efficiency decreases effectively but the reduction in overall efficiency is remarkably smaller due to improvement in the disk friction losses.

Pilot study for the reliability evaluation of double suction volute pump

In this paper, the study of test methods for the reliable assessment of the amount of suction pumps which bees root fluid is sucked into both around the impeller. Bee root amount suction pump is usually used for the purpose ofdischarging a large flow rate, such as water supply plant equipment and buildings. Centrifugal pumps are currently in production in the country is the trend in the exchange according to Chapter mode changes to improve the level of technology leaks due to wear of the mechanical seal from the existing impeller wear. When the mode is changed to give chapter and developed appropriate test method for evaluating the reliability of centrifugal pumps life testing time because the calculation method differs with these failure modes.

A 2D NUMERICAL AND EXPERIMENTAL INVESTIGATION ON THE PRESSURE FLUCTUATIONS INSIDE A DOUBLE VOLUTE CENTRIFUGAL PUMP AT THREE DIFFERENT RADIAL GAPS

Pressure fluctuations in centrifugal pumps are one of the most traumatic issues that exist as a result of the interaction between the rotor and stator volute. The experiments that were carried out on the double volute pump model in Saudi Arabia have proved that the radial gap clearance between the impeller and the tongue of the volute plays a major role in increasing and decreasing that vibrations that are generated due to the pressure fluctuations. Unsteady 2D simulations were carried out on the model to study the pressure fluctuations especially at the critical locations such as around the impeller , the cutwater, and the volute tongue. The results show that the sliding mesh technique is a very useful procedure for simulating these kinds of simulations. The results also show that the peak of the pressure fluctuations occurs at the first blade passing frequency for the 3 gaps 2, 3.6, 7mm. Numerical static pressure was captured accurately for each gap but the amplitude of the pressure fluctuations were overestimated due to the inaccurate nature of the 2D simulations. The highest gap 7 mm is the best solution for the vibrations and noise reduction due to the decrease in the pressure fluctuations without affecting the performance of the pump greatly. The performance curves are discussed.

Hydrodynamic Analysis of the Flow in an Axial Rotor and Impeller for Large Storage Pump

In hydropower systems among hydropower plants there are integrated pumping stations (PS). In order to ensure higher flow rate, the pumps have constructive differences besides regular. Consequently, the complex shape of the suction-elbow with symmetric inlet generates an unsteady flow which is ingested by impeller. These phenomena's also generate stronger unsteady flow conditions, such as stall, wakes, turbulence and pressure fluctuations, which affect the overall mechanical behaviour of the pump with vibration, noise and radial and axial forces on the rotor. Alternatively, an axial rotor can be installed in front of the impeller. In this case, the flow non-uniformity will be decreased and the static pressure will be increased at the impeller inlet. Consequently, the efficiency behaviour practically remains unchanged while the cavitational behaviour is improved. From the assembly between axial rotor and centrifugal impeller, the axial rotor usually works in cavitation and is often replaced. The paper investigates experimentally and numerically the comparison between pump impeller without and with axial rotor hydrodynamics taking into account the flow given by the symmetrical suction elbow. Full three-dimensional turbulent numerical investigation of the symmetrical suction elbow, with axial rotor and without, pump impeller and volute are performed. The hydrodynamic analysis confirms that once the axial rotor is mounted in front of the pump impeller increase the static pressure and the incidence angle is improved at the inlet of the pump impeller.

Experimental and Numerical Investigation of Coating Effect on Pump Impeller and Volute

Experimental and Numerical Investigation of Coating Effect on Pump Impeller and Volute

Design optimization of double-suction volute pumps

The performance required of a double-suction volute pump differs, depending on its application. High efficiency, low shut off head, design point performance and size are all demands that require trade-offs. Here, Ebara investigates design optimization with Design of Experiments (DoE) and Computational Fluid Dynamics (CFD).

Section variation effect in diffuser analysis

Although much research on the centrifugal pump volute has been carried out, research specifically for the diffuser is sparse. This article looks at how under different operating conditions, section variations have varying effects on pump performance.

REDUCTION OF RADIAL THRUST BY USING TRIPLE-VOLUTE CASING

Radial thrust in a single volute centrifugal pump, which is a result of pressure variation in the volute casing, is investigated in order to avoid failures caused by this thrust force. Two ideas are introduced to avoid or to minimize this thrust force, the first is a double volute, and the second is a triple volute. A complete centrifugal pump design was manufactured. The volute was designed such that partition vanes could be added to change the number of volutes. Experiments were performed on single volute centrifugal pump, double volute centrifugal pump and triple volute centrifugal pump at 500, 800, and 900 rpm for each case. The thrust values of the double volute pump are always lower than that of the single volute pump specially when operating far from the best efficiency point where, the radial thrust is reduced by more than 55% at shut off and more than 40% at high discharges, while the thrust values of the triple volute are always lower than that of the single volute and double volute pumps specially when operating far from the best efficiency point where, the radial thrust is reduced by more than 70% at shut off and more than 50% at high discharges comparing to single volute and the radial thrust is reduced by more than 40% at shut off and more than 20% at high discharges comparing to double volute . However, it is to be mentioned that the best pump efficiency is always obtained for the single volute pump, compared with the other alternatives.