Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed centrifugal pumps.

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Experimental and Numerical Investigation of Pressure Fluctuation in a Low-Specific-Speed Centrifugal Pump with a Gap Drainage Impeller

Shock and Vibration ◽

10.1155/2021/5571178 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Li Zhang ◽

Hui Li ◽

Hong Xu ◽

Weidong Shi ◽

Yang Yang ◽

...

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Pressure Pulsation ◽

Internal Flow ◽

Stable Operation ◽

Simulation Methods ◽

Centrifugal Pumps ◽

Numerical Simulation Methods ◽

Low Specific Speed ◽

Specific Speed

In order to analyze the effect of impeller with different slot widths on the performance of the low-specific-speed centrifugal pumps, based on the impeller of a single-stage pump with the specific speed of 21, two gap drainage schemes with slot widths of 1.5 mm and 6.0 mm, slot diameter of 180 mm, and lap length of 5 mm were designed. Both experimental and numerical simulation methods were applied to compare the steady performance, which includes the head, efficiency, and the internal flow field distribution, and the unsteady pressure pulsation performance between new designed pumps and the original pump. The results show that gap drainage would cause a certain degree of head reduction, but a smaller slot width could achieve higher efficiency. Meanwhile, a reasonable open seam scheme can reduce the development of pressure pulsation, which provides experience and reference for the stable operation of low-specific-speed centrifugal pumps.

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Performance and Internal Flow Characteristics of a Very Low Specific Speed Centrifugal Pump

Journal of Fluids Engineering ◽

10.1115/1.2169815 ◽

2005 ◽

Vol 128 (2) ◽

pp. 341-349 ◽

Cited By ~ 36

Author(s):

Young-Do Choi ◽

Junichi Kurokawa ◽

Jun Matsui

Keyword(s):

Centrifugal Pump ◽

Reverse Flow ◽

Tangential Velocity ◽

Flow Characteristics ◽

Internal Flow ◽

Centrifugal Pumps ◽

Positive Displacement ◽

Speed Range ◽

Low Specific Speed ◽

Specific Speed

In very low specific speed range (ns<0.25), the efficiency of the centrifugal pump designed by the conventional method becomes remarkably low. Therefore, positive-displacement pumps have been widely used for long. However, the positive-displacement pumps remain associated with problems such as noise and vibration and they require high manufacturing precision. Since the recently used centrifugal pumps are becoming higher in rotational speed and smaller in size, there appear to be many expectations to develop a new centrifugal pump with high performance in the very low specific speed range. The purpose of this study is to investigate the internal flow characteristics and its influence on the performance of a very low specific speed centrifugal pump. The results show that large reverse flow at the semi-open impeller outlet decreases absolute tangential velocity considerably which in turn decreases the pumping head.

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Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Flow Field Analysis

Advances in Mechanical Engineering ◽

10.1155/2014/814108 ◽

2014 ◽

Vol 6 ◽

pp. 814108 ◽

Cited By ~ 1

Author(s):

Baocheng Shi ◽

Jinjia Wei

Keyword(s):

Turbulent Flow ◽

Centrifugal Pump ◽

Centrifugal Pumps ◽

Numerical Convergence ◽

Phase Calculation ◽

Low Specific Speed ◽

Specific Speed ◽

3D Solid ◽

Solid Liquid ◽

Numeral Simulation

For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, the iteration convergence problem caused by complex internal structure and high rotational speed of pump is always a problem for numeral simulation researchers. To solve this problem, the combination of three measures of dynamic underrelaxation factor adjustment, step method, and rotational velocity control means according to residual curves trends of operating parameters was used to improve the numerical convergence. Numeral simulation of 3D turbulent flow in a low specific speed solid-liquid centrifugal pump was performed, and the results showed that the improved solution strategy is greatly helpful to the numerical convergence. Moreover, the 3D turbulent flow fields in pumps have been simulated for the bottom ash-particles with the volume fraction of 10%, 20%, and 30% at the same particle diameter of 0.1 mm. The two-phase calculation results are compared with those of single-phase clean water flow. The calculated results gave the main region of the abrasion of the impeller and volute casing and improve the hydraulic design of the impeller in order to decrease the abrasion and increase the service life of the pump.

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2432 Internal Flow Analysis of Low Specific Speed Centrifugal Pump with Circular Casing

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2006.2.0_183 ◽

2006 ◽

Vol 2006.2 (0) ◽

pp. 183-184

Author(s):

Jun MATSUI ◽

Junichi KUROKAWA ◽

Kouichi NISHINO ◽

Young-Do Choi ◽

Kouichi MOURI

Keyword(s):

Centrifugal Pump ◽

Flow Analysis ◽

Internal Flow ◽

Low Specific Speed ◽

Specific Speed

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

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

10.1177/0954406217729420 ◽

2017 ◽

Vol 232 (17) ◽

pp. 3062-3073 ◽

Cited By ~ 3

Author(s):

M DaqiqShirazi ◽

R Torabi ◽

A Riasi ◽

SA Nourbakhsh

Keyword(s):

Flow Field ◽

Centrifugal Pump ◽

Stokes Equations ◽

Three Dimensional ◽

Volumetric Efficiency ◽

Centrifugal Pumps ◽

Disk Friction ◽

Low Specific Speed ◽

Overall Efficiency ◽

Specific Speed

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.

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Comparison of energy parameters of a centrifugal pump with a multi-piped impeller in cooperation either with an annular channel and a spiral channel

Open Engineering ◽

10.1515/eng-2018-0063 ◽

2018 ◽

Vol 8 (1) ◽

pp. 513-522 ◽

Cited By ~ 1

Author(s):

Bartłomiej Chomiuk ◽

Janusz Skrzypacz

Keyword(s):

Centrifugal Pump ◽

Annular Channel ◽

Operating Parameters ◽

Centrifugal Pumps ◽

Impeller Outlet ◽

Flow Geometry ◽

Quantitative Verification ◽

Flow Through ◽

Low Specific Speed ◽

Specific Speed

Abstract The article presents results of numerical analyzes, which raise a subject of influence of the cooperation the multi-piped impeller with a rationalized flow geometry of annular casing and volute casing for liquid flow through centrifugal pump and their operating parameters in the extremely low specific speed nq<10. The multi-piped impeller (patented by authors) is a major alternative to classic vane impellers. The stator type is responsible for the conversion of the kinetic energy of the liquid by the impeller outlet into potential energy, which determines the overall efficiency of the pump. Also, the article presents qualitative and quantitative verification of results obtained by computer modeling and an attempt to estimate their accuracy. The article focuses mainly on the comparison of the performance parameters of the pump with a multi-piped impeller in cooperation with two stator types with a rationalized flow geometry. Both outlet elements were tested in various configurations of constructional features. The complexity of the construction of the stator can significantly affect the manufacturing costs of pump unit. Knowledge concerning construction of hydraulic elements of centrifugal pumps working in the range of parameters corresponding specific speed (nq<10) is insufficient. As shown in the paper, the annular type casing model pump cooperating with a multi-piped impeller, designed in accordance with literature, reached far poorer operating parameters than the rational annular construction in a configuration with the same impeller.

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Investigation on the Internal Flow Characteristics of the Low Specific Speed Centrifugal Pump with Circular Casing

Journal of the Korean Society of Marine Engineering ◽

10.5916/jkosme.2008.32.3.404 ◽

2008 ◽

Vol 32 (3) ◽

pp. 404-412 ◽

Cited By ~ 1

Author(s):

Young-Do Choi

Keyword(s):

Centrifugal Pump ◽

Flow Characteristics ◽

Internal Flow ◽

Low Specific Speed ◽

Specific Speed

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Very Low Specific Speed Centrifugal Pump—Hydraulic Design and Physical Limitations

Journal of Fluids Engineering ◽

10.1115/1.4039250 ◽

2018 ◽

Vol 140 (7) ◽

Cited By ~ 2

Author(s):

Grunde Olimstad ◽

Morten Osvoll ◽

Pål Henrik Enger Finstad

Keyword(s):

Centrifugal Pump ◽

Low Flow ◽

Centrifugal Pumps ◽

Hydraulic Design ◽

New Findings ◽

Gear Pumps ◽

Disk Friction ◽

Low Specific Speed ◽

High Head ◽

Specific Speed

For low-flow and high-head applications, pump types such as progressive cavity or gear pumps are often used. However, centrifugal pumps are much more robust and wear resistant, and are beneficial if they can handle the rated head and flows. By challenging the limitations of low specific speed (Nq), centrifugal pumps can be made to handle a combination of low flow and high head, which previously required other pump types. Conventional centrifugal pumps have specific speed down to 10, while in this paper a design with specific speed of 4.8 is presented. The paper describes several iterative steps in the design process of the low Nq pump. These iterations were done one physical pumps, which were successively tested in a test rig. Motivation for each step is explained theoretically and followed up by discussion of the measured results. Four different geometries of the pump were tested, all of them manufactured by rapid prototyping in nylon material. A substantial question is how low the specific speed of a centrifugal pump can be. Limitations of low Nq pumps are discussed and new findings are related to volute cavitation. In addition, limitations due to disk friction, volute losses, leakage flow, and pump stability are discussed and show to limit the design space for the pump designer.

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Analysis on Effects of the Blade Wrap Angle and Outlet Angle on the Performance of the Low-Specific Speed Centrifugal Pump

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.354-355.615 ◽

2011 ◽

Vol 354-355 ◽

pp. 615-620 ◽

Cited By ~ 1

Author(s):

Wei Li ◽

Wei Dong Shi ◽

Ting Jiang ◽

Yan Xu ◽

Tong Tong Li

Keyword(s):

Centrifugal Pump ◽

Stokes Equations ◽

Internal Flow ◽

Navier Stokes ◽

Outlet Angle ◽

Study Results ◽

Wrap Angle ◽

Low Specific Speed ◽

Specific Speed ◽

Blade Wrap Angle

In order to research the effect of the blade wrap angle and outlet angle on the hydraulic performance of the low-specific speed sewage pump, the Reynolds time-averaged Navier-Stokes equations was discretized based on the finite volume method, and the modified k-ε turbulence model were chosen in FLUENT. Numerical simulation of the internal flow within the centrifugal pump with the specific speed of 60 at different blade wrap angle and outlet angle is carried out. The analysis of the velocity and the turbulent kinetic energy distribution in different cases, and predicts the external characteristics of the several cases based on the loss analysis method. The study results show that the efficiency of pumps increase with decreasing the outlet angle and increasing the wrapping angle at the design of sewage pumps. According to the analysis, changing the blade outlet Angle has much more influence on the performance of the pump than changing the wrap angle.

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