Single-blade Centrifugal Pump Research Articles

Performance and radial thrust of single-blade reverse running pump turbine

In this study, we proposed the use of a single-blade centrifugal pump, which is widely used as a sewage pump, as a reverse running water turbine with the aim of realizing a nonblocking water turbine. The single-blade centrifugal pumps allow large particles to pass through, and we are hopeful that their use in water turbines will lead to a high degree of passage of foreign bodies. However, what must also be considered is that an excessive fluctuating radial thrust acts upon the runner. Therefore, the performance and the radial thrust of a single-blade reverse running pump turbine were investigated with experiments and numerical analyses, and the component analysis was performed for the radial thrust. The results showed that time-averaged value and fluctuating component of total radial thrust increased as the flow rate increased, and that the dominant components among the fluctuating component of the hydraulic part radial thrust changed depending on the flow rate. This makes it possible to which component to be focused on for each flow rate to examine whether the radial thrust should be reduced or not.

Research on Influence of Rotation Center Eccentricity on Radial Force of Single-Blade Centrifugal Pump

To estimate the influence of the rotation center eccentricity of the single-blade centrifugal pump impeller on the radial force on it, and to explore the effective radial force balance method, a single blade pump with a power of 2.2 kW is analyzed. The accuracy of Numerical Simulation Methods are verified by tests of external characteristics (under three rotation-speeds of 1470 r/min, 2000 r/min, and 2940 r/min) and pressure distributions. There are five models with different rotation center coordinates (model a with (0,1), model b with (−1,0), model c with (0,−1), model d with (1,0), and model e with (0,0.5)) which are analyzed. The results show that the radial force of model c and model d reduced by 8.1% and 9.8%, respectively, which means the offset of the center of the impeller to the positive direction of the x-axis and the negative direction of the y-axis can effectively reduce the radial force. At the eccentricity of the impeller (2,−2), the radial force under all operating conditions is reduced, most obviously at 1.0 Qd, which is about 17%. The study may prove helpful to designers and pump manufacturers to find a path forward for an optimal eccentricity to minimize the radial force.

Influence of blade inlet angle on the performance of a single blade centrifugal pump

Single blade centrifugal pump is suitable for transporting sewage water with large obstacles in diameter, which is required to achieve high performance. The blade inlet angle is a parameter that affects the performance of the single blade centrifugal pump. However, the selection of blade inlet angle is frequently based on experiences and demonstrates certain arbitrariness. Therefore, six impellers with different blade inlet angles are designed using ANSYS Bladegen and NX software. These impellers are categorized into Groups 1 and 2. The blade inlet angle of the impellers in Group1/Group2 increases/decreases from the front shroud to the rear one, respectively. Subsequently, the numerical simulation is carried out to investigate the effect of the blade inlet angle on the performance of the single blade pump. The blade inlet angle has more obvious influence on the head, efficiency, and shaft power for the impellers in Group 1 than those in Group 2. The lowest pressure is negative for one of the impellers in Group 1. Moreover, an optimum blade inlet angle improves the pump performance. In addition, the alternating load is small on the blades of the impellers in Group 2. The present results are helpful in designing the single blade centrifugal pump and improving its performance.

Approach to 3D Unsteady CFD Analysis of a Single-Blade Pump

Single-blade centrifugal pumps are hydraulic machines used in many industrial areas. A unique screw shaped blade enables liquids containing solids and fibrous matters to be pumped. Owing to good pump hydraulic properties on the one hand and unfavourable impeller mechanical properties on the other have single-blade pumps become recently more interesting for researchers regarding the CFD simulations. In this case a conventional CFD approach for multi-blade pumps cannot be applied due to the lack of symmetry of the single-blade impeller. Possible approaches to the CFD simulation of a single-blade impeller in the Ansys Fluent and the Ansys CFX are compared in this paper. A comparison of two CFD meshing tools showed substantial element number decrease of the whole CFD model. This paper presents also the laboratory experiment results of the investigated single-blade pump. The paper describes a new approach to the single-blade CFD simulation through Ansys Fluent which is faster and more user-friendly then the conventional approach.

Balancing and blade-shaping of a single-blade impeller

Single-blade centrifugal pumps with a screw-shaped blade are widely used to pump slurry water containing solids and fibrous matters. These hydraulic machines should be frequently used, because of their suitable hydraulic and mechanical properties, in many industrial areas. There cannot be applied a conventional method to design a single-blade impeller, due to its lack of symmetry. The designing of an impeller, which enables fulfilled main requests such as good hydraulic, mechanical properties and the ball passage diameter as well as the influence of the blade outlet angle on hydraulic parameters is described in this academic paper.

Effect of a blade shape on hydraulic and mechanical properties of a single - blade impeller

Single-blade centrifugal pumps with a screw-shaped blade are perspective hydraulic machines with possible usage in many areas. According to the non-symmetrical impeller shape, mechanical properties, resulting from a dynamic balancing, are not fulfilled automatically. The way of designing of an impeller which enables fulfilled main requests such as good hydraulic, mechanical properties and the ball passage diameter, is described in this academic paper.

Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blades of Different Blade Outlet Angles

Single-blade centrifugal impellers for sewage systems undergo both unsteady radial and axial thrusts. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces and determine the generation mechanism behind them. In this study, we conducted component analyses of radial and axial thrusts of closed, single-blade centrifugal pumps with different blade outlet angles by numerical analysis while considering leakage flow. The results revealed the effect of the blade outlet angle on the components of radial and axial thrusts. For increased flow rates, the time-averaged values of the pressure component were similar for all impellers, although its fluctuating components were higher for impellers with larger blade outlet angles. Moreover, the fluctuating inertia component of the impeller with a blade outlet angle of 8° decreased as the flow rate increased, whereas those with 16° and 24° angles increased. Therefore, the radial thrust on the hydraulic part was significantly higher for impellers with high blade outlet angles.

Dynamic stress analysis of sewage centrifugal pump impeller based on two-way coupling method

Current research on the operational reliability of centrifugal pumps has mainly focused on hydrodynamic instability. However, the interaction between the fluid and structure has not been sufficiently considered; this interaction can cause vibration and dynamic stress, which can affect the reliability. In this study, the dynamic stresses in a single-blade centrifugal pump impeller are analysed under different operating conditions; the two-way coupling method is used to calculate the fluid-structure interaction. Three-dimensional unsteady Reynolds-averaged Navier-Stokes equations are solved with the SST k-ω turbulence model for the fluid in the whole flow passage, while transient structure dynamic analysis is used with the finite element method for the structure side. The dynamic stresses in the rotor system are computed according to the fourth strength theory. The stress results show that the highest stress is near the loose bearing and that the equivalent stress increases with the flow rate because the dynamic stresses are closely related to the pressure load. The stress distributions on the blade pressure side, suction side, leading edge, and trailing edge are each analysed for different flow rates; the highest stress distribution is found on the pressure side. On the blade pressure side, a relatively large stress is found near the trailing edge and hub side. Based on these results, a stress distribution prediction method is proposed for centrifugal pumps, which considers the interaction between the fluid and structure. The method can be used to check the dynamic stress at different flow rates when optimising the pump design to increase the pump reliability.

Fluid-structure coupling effects on periodically transient flow of a single-blade sewage centrifugal pump

A partitioned fluid-structure interaction (FSI) solving strategy that depends on problem characteristics is applied to quantitatively obtain the coupling effects of a fluid-structure system in a single-blade centrifugal pump on the unsteady flow. A two-way coupling method is employed to realize strong FSI effects in the calculation procedure. The successful impeller oscillation measurement using two proximity sensors validated the FSI simulation accuracy in a complicated and practical fluid-structure system having a rotating component. The results show that the hydrodynamic force deviation can be observed in the results for the coupled versus uncoupled cases. Additionally, the coupled unsteady pressure is larger than the uncoupled value for every monitoring point at every impeller rotation position. Comparison results for different monitoring points under an overload condition and partial-load condition display the same regularities. To some extent, this interaction mechanism would affect the accuracy and reliability of the unsteady flow and rotor deflection analysis.

Effect of blade outlet angle on radial thrust of single-blade centrifugal pump

Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate. In addition to the increase of the fluctuation component of this pressure component, because the fluctuation component of the inertia and momentum components becomes large (as mentioned above), the radial thrust increases at a large flow rate, as is the case for the impeller with a large blade outlet angle.

Numerical analysis of periodic flow unsteadiness in a single-blade centrifugal pump

In this paper, the CFD simulation and new flow unsteadiness analysis for a single-blade centrifugal pump with whole flow passage were carried out. The periodic flow unsteadiness has been quantitatively investigated in detail by defining unsteady intensity and turbulence intensity in both rotor and volute domains under design condition Q=33 L s−1. The results show that the distributions of flow unsteadiness are the functions of impeller rotating angle φ and have complex unsteady characteristics. The obvious Tu fluctuations can be also observed for different impeller positions. In addition, time-averaged unsteady intensity and time-averaged turbulence intensity were calculated by averaging the results of each mesh node for entire impeller revolution period to evaluate the strength distributions of flow unsteadiness directly and comprehensively. The accumulative results of an impeller revolution can directly show the positions and strength of the flow unsteadiness and turbulence intensity in both rotor and stator domains which can be an important aspect to be considered in the single-blade pump optimum design procedure for obtaining more stable inner flow of the pump and decreasing flow-induced vibration and noise. The flow unsteadiness in the side chamber cannot be neglected for an accurate prediction of the inner flow of the pump, and the optimizing design procedure for a single-blade pump impeller will not be accurate using CFD tool if the unsteady flow phenomenon in the side chamber is not considered.

404 クローズド形一枚羽根遠心ポンプの変動流体力に及ぼすライナリング隙間の影響(OS3-5 オーガナイズドセッション《熱・流体・エネルギー変換工学の進展》)

404 クローズド形一枚羽根遠心ポンプの変動流体力に及ぼすライナリング隙間の影響(OS3-5 オーガナイズドセッション《熱・流体・エネルギー変換工学の進展》)

Radial Thrust of Single-Blade Centrifugal Pump

Single-blade centrifugal pumps are widely used as sewage pumps. However, the impeller of a single-blade pump is subjected to strong radial thrust during pump operation because of the geometrical axial asymmetry of the impeller. Therefore, to improve pump reliability, it is necessary to quantitatively understand radial thrust and elucidate the behavior and mechanism of thrust generating. This study investigates the radial thrust acting up on a single-blade centrifugal impeller by conducting experiments and CFD analysis. The results show that the fluctuating component of radial thrust increases as the flow rate deviates from the design flow rate to low or high value. Radial thrust was modeled by a combination of three components, inertia, momentum, and pressure by applying an unsteady conservation of momentum to the impeller. The sum of these components agrees with the radial thrust calculated by integrating the pressure and the shearing stress on the impeller surface. The behavior of each component was shown, and the effects of each component on radial thrust were clarified. The pressure component has the greatest effect on the time-averaged value and the fluctuating component of radial thrust. The time-averaged value of the inertia component is nearly 0, irrespective of the change in the flow rate. However, its fluctuating component has a magnitude nearly comparable with the pressure component at a low flow rate and slightly decreased with the increase in flow rate.

205 クローズド形一枚羽根遠心ポンプの変動流体力に関する研究(OS3-(1)オーガナイズドセッション《熱・流体・エネルギー変換工学の進展》)

Closed-type centrifugal pump with single-blade is used as a sewage pump widely. However, closed-type single-blade centrifugal pump impeller is acted on a large thrust during the pump operation because the impeller is an asymmetry geometrically. In addition, the hydrodynamic force is expected to act outside of the rear shroud and the front shroud in the closed-type impeller. Therefore when the reliability of the pump is secured, it is necessary to grasp the hydrodynamic force quantitatively and elucidate the behavior. This study investigated behavior of the radial thrust, consideration of the leakage flow outside of the rear shroud and front shroud. As a result, the effect of the leakage flow outside of the rear shroud and front shroud on the radial thrust was clarified.

羽根出口角の異なる一枚羽根遠心ポンプの損失解析(流体工学,流体機械)

Single-blade centrifugal pump is used as a sewage pump widely. However, hydraulic losses increase because the impeller width is large as for single-blade centrifugal pump. It is extremely complicated, besides, because the internal flow of single-blade centrifugal pump changes greatly by an impeller position and changes by the flow rate. Therefore, a quantitative prediction and the elucidation of the generation mechanism of unsteady hydraulic losses are expected to make this kind of pump high efficiency. In this study, loss analysis was performed about two kinds of single-blade centrifugal impeller with different impeller outlet angle. As a result, the effect of the impeller outlet angle which gave it to performance and hydraulic losses was clarified. Furthermore, the momentary behavior of performance and hydraulic losses was shown, and their relations with the impeller inlet and outlet flow became clear.

1108 一枚羽根遠心ポンプのラジアルスラストに及ぼす羽根出口角の影響(OS11-2 流体機械の諸問題,オーガナイズドセッション)

Single-blade centrifugal pump is widely used as a sewage pump. However, a single-blade is acted on by a large thrust during the pump operation. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impeller of different impeller outlet angle by an experiment and CFD analysis.

一枚羽根遠心羽根車の設計法に関する研究(流体工学,流体機械)

The sewage pump are demanded a high pump efficiency and a performance in passing foreign bodies. Therefore, the impeller used by these usages demands the large passing particle size (minimum particle size in the pump). However, because conventional design method of pump impeller calculates impeller exit width small, it is difficult to apply to single-blade centrifugal pump impeller which is used as a sewage pump. This paper proposes design method for single-blade centrifugal pump impeller. As a result, the head curve of the impeller by this design method satisfied a design point, and pump efficiency was over 62% more than conventional single-blade centrifugal pump impeller. Having compared design values and CFD analysis values, the suction velocity ratio of the design parameter accorded well, but the relative velocity ratio did not agree by the influence of the backflow of the impeller entrance.

Design Method for Single-Blade Centrifugal Pump Impeller

The sewage pumps are demanded a high pump efficiency and a performance in passing foreign bodies. Therefore, the impeller used by these usages requires the large passed particle size (minimum particle size in the pump). However, because conventional design method of pump impeller results in small impeller exit width, it is difficult to be applied to the design of single-blade centrifugal pump impeller which is used as a sewage pump. This paper proposes a design method for single-blade centrifugal pump impeller. As a result, the head curve of the impeller designed by the proposed design method satisfied design specifications, and pump efficiency was over 62% more than conventional single-blade centrifugal pump impeller. By comparing design values with CFD analysis values, the suction velocity ratio of the design parameter agreed well with each other, but the relative velocity ratio did not agree due to the influence of the backflow of the impeller entrance.

Instantaneous Pressure Distribution between Blades and Fluctuating Radial Thrust in the Single Blade Centrifugal Pump

Instantaneous Pressure Distribution between Blades and Fluctuating Radial Thrust in the Single Blade Centrifugal Pump

Instantaneous Interblade Pressure Distributions and Fluctuating Radial Thrust in a Single-blade Centrifugal Pump

Although single-blade centrifugal pumps are frequently used to handle waste water with solids, they have poor durability because they show severe vibration caused by a fluctuating radial thrust. Very few reports on the fluctuating radial thrust of turbo-machines have been published to date. Hence, details of the behavior and mechanism of the fluctuating radial thrust remain unclear, and a method for reducing the fluctuation is not established. In this report, instantaneous blade surface pressure distributions affected by volute pressure distributions are measured on the suction cover surface of a pump with an open-type centrifugal impeller having one blade. The fluctuating radial thrust mechanism is then clarified on the basis of these measurements, and a difference between actual radial thrust and the integrated value of static pressure along the impeller outlet is discussed. Furthermore, the radial thrust is separated into dynamic and static radial thrust vectors and a method for reducing the dynamic components, which are the cause of pump vibration, is demonstrated.