A Numerical Study on the Improvement of Suction Performance and Hydraulic Efficiency for a Mixed-Flow Pump Impeller

This paper describes a numerical study on the improvement of suction performance and hydraulic efficiency of a mixed-flow pump by impellers. The design of these impellers was optimized using a commercial CFD (computational fluid dynamics) code and DOE (design of experiments). The design variables of meridional plane and vane plane development were defined for impeller design. In DOE, variables of inlet part were selected as main design variables in meridional plane, and incidence angle was selected in vane plane development. The verification of the experiment sets that were generated by2kfactorial was done by numerical analysis. The objective functions were defined as the NPSHre (net positive suction head required), total efficiency, and total head of the impellers. The importance of the geometric design variables was analyzed using2kfactorial designs. The interaction between the NPSHre and total efficiency, according to the meridional plane and incidence angle, was discussed by analyzing the2kfactorial design results. The performance of optimally designed model was verified by experiments and numerical analysis and the reliability of the model was retained by comparison of numerical analysis and comparative analysis with the reference model.

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Three-objective optimization of a mixed-flow pump impeller for improved suction performance and efficiency

Advances in Mechanical Engineering ◽

10.1177/1687814019898969 ◽

2019 ◽

Vol 11 (12) ◽

pp. 168781401989896 ◽

Cited By ~ 1

Author(s):

Sung Kim ◽

Yong-In Kim ◽

Jin-Hyuk Kim ◽

Young-Seok Choi

Keyword(s):

Design Optimization ◽

Design Flow ◽

Meridional Plane ◽

Angle Distribution ◽

Blade Angle ◽

Mixed Flow ◽

Pump Impeller ◽

Design Variables ◽

Suction Performance ◽

Flow Pump

In this article, design optimization was carried out to improve the suction performance and efficiency of a mixed-flow pump impeller. Commercial computational fluid dynamics code and a response surface method were used in the optimization to design a mixed-flow pump impeller. When it comes to a mixed-flow pump, the two main research objectives namely efficiency and suction performance tend to contradict. It is very important that the design technology improves the suction performance while maintaining high efficiency. Meridional plane and vane plane development variables were defined in the design of the impeller. The meridional plane expresses the shapes and sizes of the blades, while the vane plane development describes the impeller inlet and outlet angles as well as the blade angle distribution. The blade angle distribution of the impeller was designed using the traditional method by which inlet and outlet angles are connected smoothly. The surface response method was applied to the design variables of the impeller inlet part in this design optimization because they influence the performance of the mixed-flow pump. Objective functions were set to satisfy the total head at the design flow rate as well as to improve efficiency and suction performance. Design variables of the impeller inlet part of the mixed-flow pump and the changes in performance were analyzed in order to produce the optimal shape. The performance of the optimally designed shape was verified by numerical analysis, and the reliability of the test result was checked by comparative analysis against the reference model.

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Design Optimization for the Hydraulic Efficiency Improvement of a Mixed-Flow Pump Diffuser

Volume 1A: Symposia, Part 2 ◽

10.1115/ajkfluids2015-09206 ◽

2015 ◽

Author(s):

Sung Kim ◽

Kyoung-Yong Lee ◽

Ji-Hyuk Kim ◽

Young-Seok Choi

Keyword(s):

Design Optimization ◽

Meridional Plane ◽

Total Efficiency ◽

Mixed Flow ◽

Design Variables ◽

Total Head ◽

Blade Shape ◽

Computational Fluid Dynamics Cfd ◽

Geometric Variables ◽

Flow Pump

In this paper, design optimization for mixed-flow pump diffusers was carried out using a commercial computational fluid dynamics (CFD) code and design-of-experiments (DOE). The design variables of meridional plane and vane plane development were defined for the diffuser design. The blade shape of the diffuser was designed using the traditional method, in which the inlet and exit angles are connected smoothly. First, the design optimization of the defined design variables for vane plane development was achieved. Next, design optimization of the defined design variables for the meridional plane was performed. The objective functions were defined as the total head and total efficiency of the diffusers. The importance of the geometric design variables was analyzed using 2k factorial designs, and the design optimization of the geometric variables was determined using the response surface method (RSM). The numerical results for reference and optimum models in this work were compared and discussed.

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Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

Advances in Mechanical Engineering ◽

10.1177/1687814020914790 ◽

2020 ◽

Vol 12 (4) ◽

pp. 168781402091479 ◽

Cited By ~ 2

Author(s):

Yong-In Kim ◽

Hyeon-Mo Yang ◽

Jun-Won Suh ◽

Sung Kim ◽

Kyoung-Yong Lee ◽

...

Keyword(s):

Numerical Study ◽

Incidence Angle ◽

Experimental Tests ◽

Design Flow ◽

Inlet Pressure ◽

Mixed Flow ◽

Bubble Generation ◽

Cavitation Phenomenon ◽

Suction Performance ◽

Flow Pump

In this study, two types of mixed-flow pump models exhibiting different suction performances were investigated to understand the cavitation characteristics of head drop gradients due to the decrease in inlet pressure. Both models were designed with the same specifications except for the shroud inlet blade angle and inlet radius which directly affect the incidence angle. The steady- and unsteady-state analyses were performed using ANSYS CFX, and the results of both models were compared. Bubble generation and patterns were systemically represented at the design flow rate to observe their influence on suction performance. Furthermore, experimental tests were performed to validate the numerical results. From the results, the head drop gradient can determine the suction performance of mixed-flow pumps. The amount and shape of the bubbles concerning the suction performance of a mixed-flow pump exhibit significant differences with the changes in time and inlet pressure. The patterns of generated bubble are not stable even for each blade.

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Variation of Hydraulic Performance by Impeller Trimming of a Mixed-Flow Pump

Volume 1A: Symposia, Part 2 ◽

10.1115/ajkfluids2015-09205 ◽

2015 ◽

Author(s):

Hyeonmo Yang ◽

Sung Kim ◽

Kyoung-Yong Lee ◽

Young-Seok Choi ◽

Jin-Hyuk Kim

Keyword(s):

Numerical Analysis ◽

Stokes Equations ◽

Three Dimensional ◽

Navier Stokes ◽

Total Efficiency ◽

Mixed Flow ◽

Navier Stokes Equations ◽

Ansys Cfx ◽

Total Head ◽

Flow Pump

One of the best examples of wasted energy is the selection of oversized pumps versus the rated conditions. Oversized pumps are forced to operate at reduced flows, far from their highest efficiency point. An unnecessarily large impeller will produce more flow than required, wasting energy. In the industrial field, trimming the impeller diameter is used more than changing the rotation speed to reduce the head of a pump. In this paper, the impeller trimming method of a mixed-flow pump is defined, and the variation in pump performance by reduction of the impeller diameter was predicted based on computational fluid dynamics. The impeller was trimmed to the same meridional ratio of the hub and shroud, and was compared in five cases. Numerical analysis was performed, including the inlet and outlet pipes in configurations of the mixed-flow pump to be tested. The commercial CFD code, ANSYS CFX-14.5, was used for the numerical analysis, and a three-dimensional Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were used to analyze incompressible turbulence flow. The performance parameters for evaluating the trimmed pump impellers were defined as the total efficiency and total head at the designed flow rate. The numerical and experimental results for the trimmed pump impellers were compared and discussed in this work.

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Effect of Tip Clearance on Suction Performance at Different Flow Rates in a Mixed Flow Pump

Volume 1B, Symposia: Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Multiscale Methods for Multiphase Flow; Noninvasive Measurements in Single and Multiphase Flows ◽

10.1115/fedsm2014-21207 ◽

2014 ◽

Author(s):

Yo Han Jung ◽

Young Uk Min ◽

Jin Young Kim

Keyword(s):

Performance Test ◽

Stokes Equations ◽

Flow Characteristics ◽

Tip Clearance ◽

Low Flow ◽

Tip Leakage Flow ◽

Mixed Flow ◽

Flow Rates ◽

Suction Performance ◽

Flow Pump

This paper presents a numerical investigation of the effect of tip clearance on the suction performance and flow characteristics at different flow rates in a vertical mixed-flow pump. Numerical analyses were carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations. Steady computations were performed for three different tip clearances under noncavitating and cavitating conditions at design and off-design conditions. The pump performance test was performed for the mixed-flow pump and numerical results were validated by comparing the experimental data for a system characterized by the original tip clearance. It was shown that for large tip clearance, the head breakdown occurred earlier at the design and high flow rates. However, the head breakdown was quite delayed at low flow rate. This resulted from the cavitation structure caused by the tip leakage flow at different flow rates.

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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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Multi-Objective Design Optimization of a Mixed-Flow Pump

Volume 1: Symposia, Parts A, B and C ◽

10.1115/fedsm2009-78348 ◽

2009 ◽

Cited By ~ 4

Author(s):

Yumiko Takayama ◽

Hiroyoshi Watanabe

Keyword(s):

Performance Characteristic ◽

Performance Characteristics ◽

Inverse Design ◽

Surface Model ◽

Objective Functions ◽

Mixed Flow ◽

Multi Objective ◽

Design Variables ◽

Flow Head ◽

Flow Pump

In most cases of high specific speed mixed-flow pump applications, it is necessary to satisfy more than one performance characteristic such as deign point efficiency, shut-off power/head and non-stall characteristic (no positive slope in flow-head curve). However, it is known that these performance characteristics are in relation of trade-offs. As a result, it is difficult to optimize these performance characteristics by conventional way such as trial and error approach by modifying geometrical parameters. This paper presents the results of the multi-objective optimization strategy of mixed-flow pump design by means of three dimensional inverse design approach, Computational Fluid Dynamics (CFD), Design of Experiments (DoE), response surface model (RSM) and Multi Objective Genetic Algorism (MOGA). The parameters to control blade loading distributions and meridional geometries for impeller and diffuser blades in inverse design were chosen as design variables of the optimization process. Pump efficiency, maximum slope in flow-head curve and shut-off power/head were selected as objective functions. Objective functions of pumps, designed by design variables specified in DoE, were evaluated by using CFD. Then, trade-off relations between objective functions were analyzed by using Pareto fronts obtained by MOGA. Some pumps which have specific performance characteristic (non-stall, low shut-off power, high efficiency etc.) designed along the Pareto front were numerically evaluated.

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