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

2014 ◽  
Vol 6 ◽  
pp. 814108 ◽  
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.

scholarly journals Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Performance Comparison of Four Geometric Models

2014 ◽  
Vol 6 ◽  
pp. 678271
Author(s):  
Baocheng Shi ◽  
Jinjia Wei
Keyword(s):  
Turbulent Flow ◽  
Centrifugal Pump ◽  
Centrifugal Pumps ◽  
Pump Performance ◽  
Geometric Models ◽  
The Real ◽  
Low Specific Speed ◽  
Specific Speed ◽  
3D Solid ◽  
Solid Liquid

For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, there exist several problems including how to design geometrical shape of the calculation model to represent the real pump and how to predict pump performance accurately to guide the design of pump. To solve these problems, four kinds of geometric models were designed. The performance of a low specific speed solid-liquid centrifugal pump was predicted, and the results showed that the improved prediction methods are more accurate than the traditional method. Moreover, the simulation results of the entire flow field of the geometric model including balance holes and the lateral clearances of impeller in which liquid rotates with half speed of impeller are closer to the real situation.

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

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

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.

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

2017 ◽  
Vol 232 (17) ◽  
pp. 3062-3073 ◽  
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.

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

2018 ◽  
Vol 8 (1) ◽  
pp. 513-522 ◽  
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.

Turbulent Flow Simulation Study Applied to Centrifugal Pumps with Low Specific Speed

2000 ◽  
Vol 2000.4 (0) ◽  
pp. 35-36
Author(s):  
Tomotatsu NAGAFUJI ◽  
Akinori FURUKAWA ◽  
Eiji ASAKURA ◽  
Hideyuki KAWAJIRI
Keyword(s):  
Turbulent Flow ◽  
Simulation Study ◽  
Flow Simulation ◽  
Centrifugal Pumps ◽  
Low Specific Speed ◽  
Specific Speed

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

2018 ◽  
Vol 140 (7) ◽  
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.

An analytical method for determining the optimum number of blades of the compound impeller in a low specific speed centrifugal pump

2020 ◽  
Vol 234 (6) ◽  
pp. 576-587
Author(s):  
Yu-Liang Zhang ◽  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Analytical Method ◽  
Full Length ◽  
Optimum Number ◽  
Centrifugal Pumps ◽  
Design Point ◽  
Closed Type ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Good Agreement

Reasonable methods for determining the optimum number of blades in a low specific speed centrifugal pump with closed-type impeller with splitters, i.e. compound impeller have been rather rare in the literature so far. In the article, a new analytical method was put forward to determine such an optimum number of blades by including the effect of turbulent boundary layer over impeller blades. Three conventional impellers with different numbers of full-length blades and two compound impellers with different numbers of splitters were designed and manufactured. The corresponding performance tests were then conducted. Results showed that the optimum numbers of blades exist for two kinds of impeller in terms of head at design point, pump efficiencies at design point and best efficiency point, and slope of head-flow rate curve at shut-off point. The estimated optimum numbers of blades are in good agreement with the numbers based on the experiments. The conventional impellers with full-length blades are more prone to the hump phenomenon than the compound impellers at the optimum numbers of blades. For the compound impellers, however, the hump effect is negligible at the optimum number of blades, and their head and efficiency are higher than those for the impellers with full-length blades. The method is applicable to compound impeller design in low specific speed centrifugal pumps.

Experimental Studies on the Optimization Design of a Low Specific Speed Centrifugal Pump

2011 ◽  
Author(s):  
Jinfeng Zhang ◽  
Ye Yuan ◽  
Shouqi Yuan ◽  
Weigang Lu ◽  
Jianping Yuan
Keyword(s):  
Neural Network ◽  
Centrifugal Pump ◽  
Network Model ◽  
High Efficiency ◽  
Experimental Studies ◽  
Test Scheme ◽  
Centrifugal Pumps ◽  
Marquardt Algorithm ◽  
Low Specific Speed ◽  
Specific Speed

For a low specific speed centrifugal pump with the requirement of high efficiency of 68% and non-overload power characteristics, series experimental studies, by matching 9 volutes with 19 impellers were done. By combining the former research results about the splitters and the non-overload theory in centrifugal pump, the theoretical conditions to achieve the property of non-overload in a centrifugal pump with splitters was analyzed, and formulas to estimate the maximum shaft power and its position are derived. Based on the requirement of high efficiency and non-overload, blade outlet angle β2, blade outlet width b2, volute throat are Ft and the inlet diameter of splitters Di were chosen with three levels to design a normal L9 (34) orthogonal test scheme. After the optimized design scheme was determined, and corresponding test was done also, it demonstrates that the experiment purpose was achieved and the design method to combine the splitters and non-overload theory is reasonable, which can get the property of high efficiency and non-overload. A BP artificial neural network (BPANN) model was built to predict the efficiency and head of centrifugal pumps with splitters in MATLAB toolbox. Eighty five groups of test results were used to train and test the network model, where the Levenberg–Marquardt algorithm was adopted to train the neural network model. Five parameters Q, Z, β2, Di, b2 were chosen as the input layer parameters, η and H were the output factors. Through the analysis of prediction results, the conclusion was got that, the accuracy of the BP ANN is good enough for performance prediction. And the BP ANN can be used for assisting design of centrifugal pumps with splitters, which can shorten research time and cost.

scholarly journals The Effect of Viscosity on Performance of a Low Specific Speed Centrifugal Pump

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Rouhollah Torabi ◽  
Seyyed Ahmad Nourbakhsh
Keyword(s):  
Centrifugal Pump ◽  
Stokes Equations ◽  
Reduction Rate ◽  
Viscous Fluids ◽  
Navier Stokes ◽  
Centrifugal Pumps ◽  
Navier Stokes Equations ◽  
Pump Performance ◽  
Low Specific Speed ◽  
Specific Speed

Centrifugal pump delivery head and flow rate drop effectively during the pumping of viscous fluids. Several methods and correlations have been developed to predict reduction rate in centrifugal pump performance when handling viscous fluids, but their results are not in very good agreement with each other. In this study, a common industrial low specific speed pump, which is extensively used in different applications, is studied. The entire pump, including impeller, volute, pipes, front and rear sidewall gaps, and balance holes, is simulated in Computational Fluid Dynamics and 3D full Navier Stokes equations are solved. CFD results are compared with experimental data such as pump performance curves, static pressure in casing, and disk friction loss. Dimensionless angular velocity and leakage rate are investigated in sidewall gap and efficiency variation due to viscosity is studied. The results demonstrate that the behavior of the fluid in sidewall gap is strictly sensitive to viscosity. Increasing viscosity improves the volumetric efficiency by reducing internal leakage through wear rings and balance holes, causing, however, a significant fall in the disk and overall efficiency. Results lead to some recommendations for designing centrifugal pumps which may be used in transferring viscous fluids.

An Experimental Study on the Effect of Oil Viscosity and Wear-Ring Clearance on the Performance of an Industrial Centrifugal Pump

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Experimental Study ◽  
Centrifugal Pump ◽  
Hydraulic Parameters ◽  
Centrifugal Pumps ◽  
Oil Viscosity ◽  
Relative Variation ◽  
Performance Curves ◽  
Shaft Power ◽  
Low Specific Speed ◽  
Specific Speed

The clearance of wear-rings in the impeller of centrifugal pumps has an important influence on the pump’s performance. Unfortunately, this effect has not been quite well documented, especially for the centrifugal pumps handling viscous oils. An industrial centrifugal pump with low specific speed was employed as a model to investigate the effect of the clearance on the performance of the pump. In this experimental study, the clearances of the wear-rings on the impeller shroud and hub were enlarged; the performances of the pump were measured when it pumped water and the viscous oils. The performance curves, the hydraulic parameters, and their relative variation ratios at best efficiency points were examined carefully for different clearances at various viscosities. The results showed that the flow rate is varied relatively in a range of −6% − +5%, the head −10% − +6%, the shaft-power + 2% −+8% and the efficiency −19% − +2%, respectively, when the clearance was enlarged from 0.25 mm to 0.85 mm at best efficiency points. The clearance of wear-rings on shroud has a more significant influence on the performance than on the hub. However, such an effect is weakened with increasing viscosity.

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