Improving the Performance of an Axial Flow Pump: An Overview

Thus far, axial flow pumps remain a significant hydrodynamic unit. These pumps have common applications for various systems that require a high flow rate and a lower head. They tend to be less efficient and consume excessive power when operating at low flow conditions. Most of the studies focus on improving the hydraulic performance of these pumps based on the best efficiency point (BEP) flow conditions. This approach is mostly based on the assumption that the pump will always operate at BEP. However, this is not always the case, because the operational condition of the pump may require an adjustment to meet certain system demands. Hence, it is necessary to emphasize the need to improve the hydraulic performance of these pumps for multiple flow conditions. This means that in addition to BEP, the lowest, and the highest operational conditions need to be considered when improving the pump performance. Also, it is important to review the phenomenon of cavitation in every design optimization investigation, given its significance to pump performance and some misrepresentation which are sometimes associated with its assessment. Therefore. the main contribution of this article is to briefly discuss the successful and unsuccessful design optimization methods of an axial flow pump. Furthermore, it highlights the significance of improving the pump performance at multiple flow conditions and also to incorporate the analysis of using CFD methods to analyze the results of cavitation performance in every pump performance improvement investigation.

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The Effect of the Thickness and Angle of the Inlet and Outlet Guide Vane on the Performance of Axial-Flow Pump

Volume 1A, Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES and Hybrid RANS/LES Methods; Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Active Fluid Dynamics and Flow Control — Theory, Experiments and Implementation ◽

10.1115/fedsm2016-7939 ◽

2016 ◽

Author(s):

Sang-Won Kim ◽

Youn-Jea Kim

Keyword(s):

Numerical Analysis ◽

Numerical Study ◽

Guide Vane ◽

Axial Flow ◽

Inlet Guide Vane ◽

Guide Vanes ◽

Pump Performance ◽

Blade Thickness ◽

Axial Flow Pump ◽

Flow Pump

An axial-flow pump has a relatively high discharge flow rate and specific speed at a relatively low head and it consists of an inlet guide vane, impeller, and outlet guide vane. The interaction of the flow through the inlet guide vane, impeller, and outlet guide vane of the axial-flow pump has a significant effect on its performance. Of those components, the guide vanes especially can improve the head and efficiency of the pump by transforming the kinetic energy of the rotating flow, which has a tangential velocity component, into pressure energy. Accordingly, the geometric configurations of the guide vanes such as blade thickness and angle are crucial design factors for determining the performance of the axial-flow pump. As the reliability of Computational Fluid Dynamics (CFD) has been elevated together with the advance in computer technology, numerical analysis using CFD has recently become an alternative to empirical experiment due to its high reliability to measure the flow field. Thus, in this study, 1,200mm axial-flow pump having an inlet guide vane and impeller with 4 blades and an outlet guide vane with 6 blades was numerically investigated. Numerical study was conducted using the commercial CFD code, ANSYS CFX ver. 16.1, in order to elucidate the effect of the thickness and angle of the guide vanes on the performance of 1,200mm axial-flow pump. The stage condition, which averages the fluxes between interfaces and is accordingly appropriate for the evaluation of pump performance, was adopted as the interface condition between the guide vanes and the impeller. The rotational periodicity condition was used in order to enable a simplified geometry to be used since the guide vanes feature multiple identical regions. The shear stress transport (SST) k-ω model, predicting the turbulence within the flow in good agreement, was also employed in the CFD calculation. With regard to the numerical simulation results, the characteristics of the pressure distribution were discussed in detail. The pump performance, which will determine how well an axial-flow pump will work in terms of its efficiency and head, was also discussed in detail, leading to the conclusion on the optimal blade thickness and angle for the improvement of the performance. In addition, the total pressure loss coefficient was considered in order to investigate the loss within the flow paths depending on the thickness and angle variations. The results presented in this study may give guidelines to the numerical analysis of the axial-flow pump and the investigation of the performance for further optimal design of the axial-flow pump.

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Fish-friendly design of an axial flow pump impeller based on a blade strike model

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919849768 ◽

2019 ◽

Vol 234 (2) ◽

pp. 173-186 ◽

Cited By ~ 1

Author(s):

Qiang Pan ◽

Weidong Shi ◽

Desheng Zhang ◽

BPM van Esch ◽

Ruijie Zhao

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Flow Behavior ◽

Integrated Design ◽

Axial Flow ◽

Hydraulic Performance ◽

Fish Mortality ◽

Computational Fluid Dynamics Analysis ◽

Axial Flow Pump ◽

Flow Pump

With environmental awareness growing in many countries, governments are taking measures to reduce mortality of migrating fish in pumping stations. Manufacturers seek to develop pumps that are less damaging to fish and still provide good hydraulic performance, but little is known about the implications design modifications may have on internal flow characteristics and overall hydraulic performance. In this paper, an integrated design method is proposed that combines a validated blade strike model for fish damage and a computational fluid dynamics method to assess the pump performance. A redesign of an existing, conventional, axial flow pump is presented as an example in this paper. It shows how the design of the impeller blades was modified stepwise in order to reduce fish mortality while its hydraulic performance was monitored. Computational fluid dynamics analysis of the flow near the hub of the highly skewed blades indicated that unconventional design modifications were required to ensure optimum flow behavior. In the final fish-friendly design, the risk of fish mortality has reduced considerably while the hydraulic performance of the pump is still acceptable for practical application.

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Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

Mathematical Problems in Engineering ◽

10.1155/2016/6375314 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Fan Yang ◽

Hao-ru Zhao ◽

Chao Liu

Keyword(s):

Prediction Model ◽

Flow Rate ◽

High Efficiency ◽

Guide Vane ◽

Axial Flow ◽

Hydraulic Performance ◽

Operating Conditions ◽

Ann Model ◽

Axial Flow Pump ◽

Flow Pump

In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

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A Closed Loop Approach to Simulate the Unsteady Three-Dimensional Flow in an Axial Flow Pump

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-30484 ◽

2010 ◽

Author(s):

Friedrich-Karl Benra ◽

Hans Josef Dohmen

Keyword(s):

Boundary Condition ◽

Boundary Conditions ◽

Mass Flow ◽

Closed Loop ◽

Constant Pressure ◽

Axial Flow ◽

Pressure Level ◽

Flow Conditions ◽

Axial Flow Pump ◽

Flow Pump

A new method is put forward to model the flow in a highly loaded axial flow pump. A directional loss model is utilized to model the function of a valve behind the pump stator vanes. A periodic boundary condition between the inlet and the outlet of the pump is applied to model a closed loop. Thus no flow specification in either the inlet or outlet of the pump is required; also it is not necessary to give the turbulence level. By this method no pressure level inside the flow domain is given by a boundary condition. To avoid numerical instability the pressure level has to be given at least at one grid point. A given constant pressure somewhere in the loop domain is physically invalid, especially at stall condition of the pump. This is avoided by introducing a reservoir with a constant pressure boundary condition that is nearly decoupled from the pressure field inside the main pump loop by a huge flow resistance. Consequently this method can avoid specifying non-physical stationary boundary conditions at the inlet and the outlet for transient simulations. The new model can predict the mass flow fluctuations in the pump. These fluctuations are not very strong at stable operating conditions but increase in part load or stalled flow conditions. The transient numerical results obtained by the new approach are compared with those obtained by the conventional simulation with stationary boundary conditions (constant total pressure at the inlet and fixed mass flow at the outlet) and also with results of experimental investigations performed by Kosyna and Stark. The different flow structures inside the blade passages of the pump are described and compared in detail for part load, overload and design point as well as for stalled flow conditions.

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Numerical simulation on hydraulic performance and tip leakage vortex of a slanted axial-flow pump with different blade angles

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211032989 ◽

2021 ◽

pp. 095440622110329

Author(s):

Zhaodan Fei ◽

Hui Xu ◽

Rui Zhang ◽

Yuan Zheng ◽

Tong Mu ◽

...

Keyword(s):

Kinetic Energy ◽

Strain Tensor ◽

Axial Flow ◽

Hydraulic Performance ◽

Tip Leakage Flow ◽

Blade Angle ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Axial Flow Pump ◽

Flow Pump

The blade angle has a great effect on hydraulic performance and internal flow field for axial-flow pumps. This research investigated the effect of the blade angle on hydraulic performance and tip leakage vortex (TLV) of a slanted axial-flow pump. The hydraulic performance and the TLV are compared with different setting angles. The dimensionless turbulence kinetic energy (TKE) is used to investigate the TLV. A novel variable fv is utilized to analyze the relation among the TLV, strain tensor and vorticity tensor. The proper orthogonal decomposition (POD) method is used to analyze TLV structure. The results show that with the increase of the blade angle, the pump head is getting larger, the flow rate of the best efficiency moves to be larger, and both the primary TLV (P-TLV) and the secondary TLV (S-TLV) are getting stronger. The P-TLV often exists in the outer edge of TKE distribution and S-TLVs often exist in the largest value area of TKE. This phenomenon is more evident with blade angle increasing. Through POD method, it shows that the first six modes contain more than 90% of TKE. The reason why the TKE value near the region of S-TLV is high is that the tip leakage flow is a kind of jet-like flow with high kinetic energy. The main structure of the P-TLV is shown in modes 4−6, resulting in a reflux zone but not with the highest TKE.

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