Numerical Investigation of Back Vane Design and Its Impact on Pump Performance

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Farzam Mortazavi ◽  
Alireza Riasi ◽  
Ahmad Nourbakhsh
Keyword(s):  
Flow Characteristics ◽  
Outer Radius ◽  
Design Parameters ◽  
Centrifugal Pumps ◽  
Complex Flow ◽  
Axial Thrust ◽  
Axial Forces ◽  
New Findings ◽  
Pump Head ◽  
Complex Flow Structure

Adding back vanes to the rear shroud of centrifugal pumps is sometimes practiced in order to alleviate large axial forces. Effective design and flow characteristics of back vanes remain obscure due to lack of knowledge associated with experimental complexities in study of this area. In this study, various design parameters of the conventional noncurved rectangular back vanes are evaluated using computational fluid dynamics (CFD). Furthermore, the complex flow structure at the rear chamber of these pumps is illustrated and discussed with the advantage of CFD which is a highly costly and taxing job if one chooses to capture it using experimental methods. Effect of back vanes outer radius, width, clearance, thickness, vane angle, and number of vanes on pump characteristics and axial thrust has been investigated. New findings of this study show that back vanes are capable of canceling the axial thrust in a large range of flow rates without a penalty to the machine efficiency, provided that suitable design parameters are selected. In addition, the best efficiency point (BEP) will not be affected by usage of back vanes. The rear chamber’s flow pattern suggest that back vanes have a repumping effect causing increased pump head at longer back vane configurations.

Fluid Flow Structure in Arterial Bypass Anastomosis

2005 ◽  
Vol 127 (4) ◽  
pp. 611-618 ◽  
Author(s):  
C. M. Su ◽  
D. Lee ◽  
R. Tran-Son-Tay ◽  
W. Shyy
Keyword(s):  
Fluid Flow ◽  
Flow Structure ◽  
Bypass Graft ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Arterial Bypass ◽  
Flow Recirculation ◽  
Area Reduction ◽  
Complex Flow Structure

The fluid flow through a stenosed artery and its bypass graft in an anastomosis can substantially influence the outcome of bypass surgery. To help improve our understanding of this and related issues, the steady Navier-Stokes flows are computed in an idealized arterial bypass system with partially occluded host artery. Both the residual flow issued from the stenosis—which is potentially important at an earlier stage after grafting—and the complex flow structure induced by the bypass graft are investigated. Seven geometric models, including symmetric and asymmetric stenoses in the host artery, and two major aspects of the bypass system, namely, the effects of area reduction and stenosis asymmetry, are considered. By analyzing the flow characteristics in these configurations, it is found that (1) substantial area reduction leads to flow recirculation in both upstream and downstream of the stenosis and in the host artery near the toe, while diminishes the recirculation zone in the bypass graft near the bifurcation junction, (2) the asymmetry and position of the stenosis can affect the location and size of these recirculation zones, and (3) the curvature of the bypass graft can modify the fluid flow structure in the entire bypass system.

Pressure Fluctuations Around Steam Control Valve: Steam Experiments and CFD Calculations

2007 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada
Keyword(s):  
Power Plant ◽  
Pressure Fluctuations ◽  
3D Structure ◽  
Flow Characteristics ◽  
Control Valve ◽  
Working Fluid ◽  
Complex Flow ◽  
Piping Systems ◽  
The Difference ◽  
Complex Flow Structure

In some cases, a steam control valve (figure 1) in a power plant causes large vibrations in piping systems that can be attributed to pressure fluctuations generated in the valve under the partial-valve-opening (middle-opening) condition. For the maintenance and the management of the plant, the valve system needs to be improved to prevent the onset of hydrodynamic instabilities. However, in the case of the steam control valve, it is difficult to understand the flow characteristics in detail experimentally because the flow around the valve has a complex 3D structure and becomes supersonic (M>1). For these reasons, the details of the flow around the valve are not fully understood before, and CFD simulations are required to understand the underlying complex flow structure associated with the valve. In our previous researches, a mechanism of the pressure fluctuations in the middle opening condition, named “rotating pressure fluctuations”, were clarified and a suppression shape were developed by experiments and CFD calculations. However, as we used air as a working fluid in our previous researches instead of steam that is used in the power plant, we couldn’t consider effects of condensation and difference of change of the state quantities between air and steam. In this report, we have conducted steam experiments and CFD calculations by original code to clarify the effects of the difference of the fluids. As a result, in the middle opening condition, we have observed spike-type pressure fluctuations and their rotation in the experiment, and valve-attached flow and local high-pressure region in the CFD result. These results indicate the pressure fluctuations observed in steam experiments and CFDs are the same as rotating pressure fluctuations observced in air researches.

Flow loss analysis of a two-stage axially split centrifugal pump with double inlet under different channel designs

2019 ◽  
Vol 233 (15) ◽  
pp. 5316-5328 ◽  
Author(s):  
Majeed Koranteng Osman ◽  
Wenjie Wang ◽  
Jianping Yuan ◽  
Jiantao Zhao ◽  
Yiyun Wang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Water Diversion ◽  
Centrifugal Pumps ◽  
Loss Analysis ◽  
Flow Losses ◽  
Water Pumping ◽  
Pumping Stations ◽  
Pump Head ◽  
Flow Loss

The double-stage axially split centrifugal pump is widely used in water diversion and water pumping stations due to their ability to deliver at high heads and large flow rate for long running hours. Their flow characteristics can be greatly influenced by the geometry of the channels between the stages, which is a prominent place for irreversible loss to occur. Numerical investigations were extensively carried out and a comparison was drawn between two multistage axially split centrifugal pumps, with different channel designs between its stages. The reliability of the numerical model was confirmed after a good agreement existed between numerical results and the experiments. Subsequently, entropy generation terms were used to evaluate turbulence dissipation to characterize the flow losses. The modified channels had a great effect on reducing swirl near the impeller eye, thereby improving pump head by 12.5% and efficiency by 4.98% at the design condition. They however induced flow impact, causing an unusual separation, which generated high turbulence dissipation at the blade surfaces. The channels and second stage impeller were identified as major areas for selective optimization since their turbulence dissipation was dominant. Consequently, entropy production analysis with computational fluid dynamics could be relied upon to reveal the loss locations for selective optimization in centrifugal pumps.

Development of High-Efficient Centrifugal Pump Through Optimization of Its Volute Tongue and Expeller Vane

2021 ◽  
Author(s):  
Abubaker Ahmed Mohammed Mohammedali ◽  
Ki-Seong Kim
Keyword(s):  
Centrifugal Pump ◽  
Design Parameters ◽  
Outer Diameter ◽  
Hydraulic Efficiency ◽  
Centrifugal Pumps ◽  
Axial Thrust ◽  
High Efficient ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Optimization ◽  
Good Agreement

Abstract Centrifugal pumps are often used for pumping liquids from one priority area to another, which require to work effectively in terms of performance and reliability. The objective of this study is enhancing the hydraulic performance and reliability of a centrifugal pump based on computational fluid dynamics (CFD) optimization. The shapes of expeller vane and volute tongue were optimized based on the following six design parameters; outer diameter, exit angle, front and rear heights, back sidewall gap, and tongue angle. The hydraulic efficiency and axial thrust were chosen as the optimization objectives. In this sense, a design of experiment (DOE) technique was utilized to generate 45 design samples. A response surface modeling (RSM) approach was employed to investigate the interaction between the parameters and objectives. The accuracy of the numerical simulation was verified by the experimental data and showed a good agreement. The optimization was found to improve the hydraulic efficiency by 2.92%, whereas the axial thrust was decreased by 7.51%.

Effect of Leakage Flow Path Wear on Axial Thrust in Downhole Electrical Submersible Pump Unit

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Abhay Patil ◽  
Marie Kasprzyk ◽  
Adolfo Delgado ◽  
Gerald Morrison
Keyword(s):  
Numerical Models ◽  
Experimental Testing ◽  
Flow Characteristics ◽  
Design Parameters ◽  
Test Time ◽  
Axial Thrust ◽  
Erosion Testing ◽  
Electrical Submersible Pump ◽  
Relationship Of ◽  
Thrust Load

Abstract Subsea production fluid is quite often characterized by the presence of frac sand, which causes wear within the pump, and alters the performance envelop. One of the design parameters critically affecting reliability is the thrust load generated by an impeller. The change in thrust load due to the erosion of the pump stages is not completely understood, and no relationship exists to foresee these reactive forces due to the complexity involved in predicting the flow characteristics. The purpose of this study is to understand the change in axial thrust due to commonly encountered wear mechanisms across the pump section especially wear across stage clearance seals. Based on in-house erosion testing of a mixed flow pump, three mesh models were built with each representing the pump condition at three different time intervals, namely, 0 h, 52 h, and 117 h of the total test time. The pump numerical models were validated using performance data collected from experimental testing. Axial thrust was found to increase with an increase in wear rate across stage seals. Since the increased clearance causes head degradation as well as an increase in thrust, the relationship of this head degradation is correlated with a change in thrust to further expand the affinity laws.

Rotordynamic Effects of the Shroud-to-Housing Leakage Flow in Centrifugal Pumps

1994 ◽  
Vol 116 (3) ◽  
pp. 558-563 ◽  
Author(s):  
E. A. Baskharone ◽  
A. S. Daniel ◽  
S. J. Hensel
Keyword(s):  
Experimental Data ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Secondary Flows ◽  
Centrifugal Pumps ◽  
Complex Flow ◽  
Pump Impeller ◽  
Rotordynamic Coefficients ◽  
Clearance Face ◽  
Complex Flow Structure

The fluid/shroud interaction forces acting on a pump impeller that is precessing around the housing centerline, are computed and the rotordynamic coefficients deduced. The numerical procedure utilized is an upgraded version of a finite-element-based perturbation model, initially devised for simple see-through annular seals. The computational model accounts for the complex flow structure in the shroud-to-housing secondary flow passage, which includes a tight-clearance face seal. The model also facilitates the mutual interaction between the primary and secondary flows near the impeller inlet and discharge stations. The numerical results are compared to existing experimental data, as well as the results of a simpler and widely used numerical model. Sources of discrepancies between the numerical results are identified, and a comprehensive assessment made in light of the experimental data.

Effect of semi-open impeller side clearance on centrifugal pump cavitation inception

2018 ◽  
Vol 1 (2) ◽  
pp. 24-39
Author(s):  
A. Farid ◽  
A. Abou El-Azm Aly ◽  
H. Abdallah
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Rotation Speed ◽  
Centrifugal Pumps ◽  
Severe Condition ◽  
Cavitation Inception ◽  
Total Input ◽  
Input Pressure ◽  
Pump Head ◽  
Pump Pressure

Cavitation in pumps is the most severe condition that centrifugal pumps can work in and is leading to a loss in their performance.  Herein, the effect of semi-open centrifugal pump side clearance on the inception of pump cavitation has been investigated.  The input pump pressure has been changed from 80 to 16 kPa and the pump side clearance has been changed from 1 mm to 3 mm at a rotation speed of 1500 rpm. It has been shown that as the total input pressure decreased; the static pressure inside the impeller is reduced while the total pressure in streamwise direction has been reduced, also the pump head is constant with the reduction of the total input pressure until the cavitation is reached. Head is reduced due to cavitation inception; the head is reduced in the case of a closed impeller with a percent of 1.5% while it is reduced with a percent of 0.5% for pump side clearance of 1mm, both are at a pressure of 20 kPa.   Results also showed that the cavitation inception in the pump had been affected and delayed with the increase of the pump side clearance; the cavitation has been noticed to occur at approximate pressures of 20 kPa for side clearance of 1mm, 18 kPa for side clearances of 2mm and 16 kPa for 3mm.

scholarly journals Low-cost Solutions for Velocimetry in Rotating and Opaque Fluid Experiments using Ultrasonic Time of Flight

2021 ◽  
Author(s):  
Fabian Burmann ◽  
Jerome Noir ◽  
Stefan Beetschen ◽  
Andrew Jackson
Keyword(s):  
Acoustic Waves ◽  
Flow Measurement ◽  
Low Cost ◽  
Time Of Flight ◽  
Zonal Flow ◽  
Gravitational Acceleration ◽  
Complex Flow ◽  
Ultrasonic Time ◽  
Theoretical Predictions ◽  
Complex Flow Structure

AbstractMany common techniques for flow measurement, such as Particle Image Velocimetry (PIV) or Ultrasonic Doppler Velocimetry (UDV), rely on the presence of reflectors in the fluid. These methods fail to operate when e.g centrifugal or gravitational acceleration leads to a rarefaction of scatterers in the fluid, as for instance in rapidly rotating experiments. In this article we present two low-cost implementations for flow measurement based on the transit time (or Time of Flight) of acoustic waves, that do not require the presence of scatterers in the fluid. We compare our two implementations against UDV in a well controlled experiment with a simple oscillating flow and show we can achieve measurements in the sub-centimeter per second velocity range with an accuracy of $\sim 5-10\%$ ∼ 5 − 10 % . We also perform measurements in a rotating experiment with a complex flow structure from which we extract the mean zonal flow, which is in good agreement with theoretical predictions.

Design and optimization of bump (compression surface) for diverterless supersonic inlet

2021 ◽  
pp. 095441002110029
Author(s):  
Irsalan Arif ◽  
Hassan Iftikhar ◽  
Ali Javed
Keyword(s):  
Fitness Function ◽  
Supersonic Jet ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Least Square ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Inlet System ◽  
Design And Optimization ◽  
Supersonic Inlet

In this article design and optimization scheme of a three-dimensional bump surface for a supersonic aircraft is presented. A baseline bump and inlet duct with forward cowl lip is initially modeled in accordance with an existing bump configuration on a supersonic jet aircraft. Various design parameters for bump surface of diverterless supersonic inlet systems are identified, and design space is established using sensitivity analysis to identify the uncertainty associated with each design parameter by the one-factor-at-a-time approach. Subsequently, the designed configurations are selected by performing a three-level design of experiments using the Box–Behnken method and the numerical simulations. Surrogate modeling is carried out by the least square regression method to identify the fitness function, and optimization is performed using genetic algorithm based on pressure recovery as the objective function. The resultant optimized bump configuration demonstrates significant improvement in pressure recovery and flow characteristics as compared to baseline configuration at both supersonic and subsonic flow conditions and at design and off-design conditions. The proposed design and optimization methodology can be applied for optimizing the bump surface design of any diverterless supersonic inlet system for maximizing the intake performance.

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