Numerical Investigation of the Transient Flow in a Centrifugal Pump Stage

2005 ◽  
Author(s):  
F.-K. Benra ◽  
H. J. Dohmen
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Pump ◽  
Transient Flow ◽  
Flow Behavior ◽  
Centrifugal Pumps ◽  
Flow Parameters ◽  
Pump Stage ◽  
Dependent Flow ◽  
Return Channel ◽  
Grid Nodes

The knowledge of the flow behavior in pump stages which consist of an impeller, a bladed diffuser and a bladed return channel is of great importance for the design of multistage centrifugal pumps. Especially the Interaction of the impeller flow with the stationary diffuser blades and the behavior of the return channel blades affect the efficiency of a pump stage in a considerable way. In this contribution the transient flow in an industrial centrifugal pump stage, which has an impeller with seven blades, a radial diffuser with ten blades and a return channel with also ten separate blades, has been simulated numerical by using the commercial software code CFX-5.7. Because of the unfavorable ratio of blade numbers a complete meshing of all flow channels was necessary. In consequence the cumulative amount of grid nodes reached a number of nearly 6 million nodes. As a result of the numerical investigation of the time dependent flow accomplished for this contribution, the influence of the rotating impeller on the flow in the stationary parts of the pump is presented in detail. All flow parameters are shown as a function of time and are discussed with respect to the position of the impeller relative to the stator blades.

scholarly journals Experimental Study of a Cavitating Centrifugal Pump During Fast Startups

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
S. Duplaa ◽  
O. Coutier-Delgosha ◽  
A. Dazin ◽  
O. Roussette ◽  
G. Bois ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Transient Flow ◽  
Flow Behavior ◽  
Rocket Engine ◽  
Rotation Velocity ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Physical Analysis ◽  
Different Types

The startup of rocket engine turbopumps is generally performed only in a few seconds. It implies that these pumps reach their nominal operating conditions after only a few rotations. During these first rotations of the blades, the flow evolution in the pump is governed by transient phenomena, based mainly on the flow rate and rotation speed evolution. These phenomena progressively become negligible when the steady behavior is reached. The pump transient behavior induces significant pressure fluctuations, which may result in partial flow vaporization, i.e., cavitation. An existing experimental test rig has been updated in the LML Laboratory (Lille, France) for the startups of a centrifugal pump. The study focuses on the cavitation induced during the pump startup. Instantaneous measurement of torque, flow rate, inlet and outlet unsteady pressures, and pump rotation velocity enable to characterize the pump behavior during rapid starting periods. Three different types of fast startup behaviors have been identified. According to the final operating point, the startup is characterized either by a single drop of the delivery static pressure, by several low-frequency drops, or by a water hammer phenomenon that can be observed in both the inlet and outlet of the pump. A physical analysis is proposed to explain these three different types of transient flow behavior.

scholarly journals Numerical Investigation of The Effect of The Number of Blades of The Impeller On The Performance of Centrifugal Pumps

2018 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Adel Pourtaghi ◽  
Heidar Pouladi
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Pump ◽  
Fluid Flows ◽  
Geometrical Parameters ◽  
Centrifugal Pumps ◽  
Small Step ◽  
Ansys Cfx ◽  
Rotating Impeller

A centrifugal pump is a pump which uses a rotating impeller for increasing the pressure of a fluid. Fluid flows to pump from the impellers hole and get accelerated by it and flows toward the volute fast from where enters to the outlet of the pump. Having enough knowledge in the field of geometrical parameters has a great effect on improving the designing and making this kind of pumps. The present study intends to take a small step in this field by evaluation of the effect of mentioned parameters and simulation of fluid current in inside the pumps. For reaching to this goal different number of blades in modelled in impellers and the performance of pump in simulated in Ansys CFX software and finally the results of CFD studies are presented as charts and curves.

Numerical Investigation of New Design of the Etoile Flow Straightener

2011 ◽  
Author(s):  
Boualem Laribi ◽  
Abdelkader Youcefi ◽  
Djelloul Belkacemi
Keyword(s):  
Velocity Profile ◽  
Numerical Investigation ◽  
Flow Behavior ◽  
Flow Parameters ◽  
Flow Metering ◽  
High Fluid ◽  
High Turbulence ◽  
High Level ◽  
High Degree ◽  
Very High

Flow metering of industrial fluids remains the concern of several researchers and exporting countries of gas and oil in the world. It is in this context that a vast numerical investigation is done in our laboratory of Industrial Fluids Measurements and Applications (FIMA). This article examines numerically a new design of the Etoile flow straightener which is described by the standard ISO 5167. This new design consists in removing the central part of the Etoile which, according to researchers, leads to a very high level of turbulence. Our intervention relates to the development and the establishment of the flow parameters downstream the Etoile with and without central part. The flow is produced by air in a 100mm pipe diameter and 40D of length with a Reynolds number of 2.5×105. The disturbance is a valve maintained 100%, 50% and 30% open. The flow parameters examined are velocity profile, turbulence intensity profile, and the fluid gyration angle. The code CFD Fluent is used for this simulation. The results obtained are compared according to directives of the standard ISO 5167. The results obtained show that for the valve settings 30% and 50% open, upstream the Etoile, we have a high turbulence level and a velocity profile with recirculation zones more significant for the valve 30% open than for the valve 50% open. It is also noted that the valve develop very high fluid gyration angle apart from the standard values. The flow behavior downstream the central part of Etoile described by the ISO 5167 is well simulated with the valve open at 100%, with a deficit of flow and a very high degree of turbulence. At this stage for the two designs, the noticed results seem so identical beyond a certain stations downstream the Etoile.

Investigation of a Centrifugal Pump Stage With Radial Impeller and a Pump Stage With Small Stage Diameter

2006 ◽  
Author(s):  
Andreas Weiten ◽  
Dieter-H. Hellmann
Keyword(s):  
Centrifugal Pump ◽  
Dynamic Performance ◽  
Axial Direction ◽  
Outer Diameter ◽  
Centrifugal Pumps ◽  
Axial Thrust ◽  
Vaned Diffuser ◽  
Pump Stage ◽  
Radial Pump ◽  
Inner Diameter

For radial multistage centrifugal pumps a combination of a radial exiting impeller, a vaned diffuser and a row of return guide vanes is used for each stage of the pump. Hence the inner diameter of the stage casing is much larger than the diameter of the impeller. In case when the space for installing the pump is limited, for example in case of submersible pumps, a high number of pump stages is necessary to produce a sufficient hydraulic head. Pump stages with an impeller diameter equal to the inner diameter of the casing can reduce the number of the stages, but up to now the efficiency of such pumps is lower than the one of a conventional pump. Improving the design of these pumps in order to increase efficiency, stationary diffusers were developed at the Institute for Turbomachinery and Fluid mechanics at TU Kaiserslautern. While the pump liquid cannot exit the impeller in radial direction, the hub diameter is reduced by the width of the impeller at the outer diameter. Hence the pump liquid now exits the impeller in axial direction. This design affects both the hydraulic and the rotor dynamic performance of the pump. Furthermore the axial thrust has dropped, because the flow and the allocation of static pressure in the impeller side spaces has changes compared to radial pump stages. In this paper results of measurements of vibration and axial thrust at radial centrifugal pump with four stages are compared with these of a four stage pump with small stage diameter. Furthermore the hydraulic datas of both designs a presented.

scholarly journals Investigations on the influence of tandem blades on inner flow and performance characteristics of centrifugal pump

2019 ◽  
Vol 234 (1) ◽  
pp. 46-55
Author(s):  
Xiaobing Shi ◽  
Jinling Lu ◽  
Lianming Zhao
Keyword(s):  
Centrifugal Pump ◽  
High Reliability ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Low Flow ◽  
Hydraulic Loss ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
And Performance

Although significant advances have been made in tandem-blade technology for axial and centrifugal compressors, little attention has been paid to its application in centrifugal pumps. In this study, we propose a new tandem-blade design method for improving inner flow characteristics and overall performance of a centrifugal pump. With the SST k − ω turbulence model, three-dimensional turbulent flow fields in the centrifugal pump with tandem blades are simulated and analyzed. The effects of tandem blades on the inner flow and performance characteristics of the centrifugal pump are investigated. The predicted velocity and pressure distributions and flow behavior of the tandem-blade impeller are compared with those of a conventional single row blade impeller. It is indicated that the centrifugal tandem-blade impeller exhibits a significant advantage in terms of the uniformity of the impeller discharge flow. The tandem blades improve the jet-wake structure and uniformity of velocity and pressure distributions at the impeller outlet, and thus reduce the pressure fluctuation and hydraulic loss. Moreover, the hump phenomenon is eliminated or alleviated under low flow rate conditions, and the tandem-blade impeller has better hydraulic performance within a wider operating range as well as high reliability. This study provides a basis for the further development of the centrifugal pump with tandem blades.

scholarly journals Flow Field Analysis and Feasibility Study of a Multistage Centrifugal Pump Designed for Low-Viscous Fluids

2021 ◽  
Vol 11 (3) ◽  
pp. 1314
Author(s):  
Mohamed Murshid Shamsuddeen ◽  
Sang-Bum Ma ◽  
Sung Kim ◽  
Ji-Hoon Yoon ◽  
Kwang-Hee Lee ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Behavior ◽  
Field Analysis ◽  
Low Flow ◽  
Design Stage ◽  
Pump Design ◽  
Second Stage ◽  
Low Viscosity ◽  
Multistage Centrifugal Pump ◽  
Return Channel

A multistage centrifugal pump is designed for pumping low-viscosity, highly volatile and flammable chemicals, including hydrocarbons, for high head requirements. The five-stage centrifugal pump consists of a double-suction impeller at the first stage followed by a twin volute. The impellers for stages two through five are single-suction impellers followed by diffuser vanes and return channel vanes. The analytical performance is calculated initially in the design stage by applying similarity laws to an existing scaled-down pump model designed for low flow rate applications. The proposed pump design is investigated using computational fluid dynamics tools to study its performance in design and off-design conditions for water as the base fluid. The design feasibility of the centrifugal pump is tested for other fluids, such as water at a high temperature and pressure, diesel and debutanized diesel. The pump design is found to be suitable for a variety of fluids and operating ranges. The losses in the pump are analyzed in each stage at the best efficiency point. The losses in efficiency and head are observed to be higher in the second stage than in other stages. The detailed flow behavior at the second stage is studied to identify the root cause of the losses. Design modifications are recommended to diminish the losses and improve the overall performance of the pump.

scholarly journals Particle Distribution and Motion in Six-Stage Centrifugal Pump by Means of Slurry Experiment and CFD-DEM Simulation

2021 ◽  
Vol 9 (7) ◽  
pp. 716
Author(s):  
Liwen Deng ◽  
Qiong Hu ◽  
Jun Chen ◽  
Yajuan Kang ◽  
Shaojun Liu
Keyword(s):  
Centrifugal Pump ◽  
Simulation Method ◽  
Test Site ◽  
Centrifugal Pumps ◽  
Mining System ◽  
Transport Characteristic ◽  
Dem Simulation ◽  
Multi Stage ◽  
Pump Stage ◽  
Slurry Transport

Six-stage centrifugal pumps are used in deep-sea mining lifting systems and are required to convey slurry containing coarse particles. A six-stage centrifugal pump suitable for operation in a natural mining system was manufactured. High-flow and full-scaled slurry conveying experiments at a 5% and 9% volume concentration of particles was carried out at a large modified test site with artificial nodules. CFD-DEM simulations were carried out to obtain slurry transport characteristic curves, particle transport and distribution characteristics, where the simulation method was validated by the experiment data. A clarified two-stage pump can be used instead of a multi-stage pump for simplified simulation calculations with acceptable accuracy. Local agglomeration of particles caused by backflow was found at the outlet of the diffuser, and such agglomeration decreased with increasing flow rates. It was found that particles are transported non-uniformly, particles transport in diffusers in strands. Particles are transported in a pulse-like mode within the pump, with the latter stage showing similar particle characteristics to those transported in the previous pump stage.

scholarly journals Experimental Investigation of Flow Instabilities and Rotating Stall in a High-Energy Centrifugal Pump Stage

2009 ◽  
Author(s):  
Stefan Berten ◽  
Philippe Dupont ◽  
Laurent Fabre ◽  
Maher Kayal ◽  
Francois Avellan ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Rotational Speed ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
High Energy ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Pump Stage

In centrifugal pumps, the interaction between the rotating impeller and the stationary diffuser generates specific pressure fluctuation patterns. When the pump is operated at off design conditions, these pressure fluctuations increase. The resulting rise of mechanical vibration levels may negatively affect the operational performance and the life span of mechanical components. This paper presents detailed pressure fluctuation measurements performed in a high speed centrifugal pump stage at full scale at various operating conditions. The impeller and stationary part (diffuser, exit chamber) of the pump stage have been equipped with piezoresistive miniature pressure sensors. The measured data in the impeller have been acquired using a newly developed onboard data acquisition system, designed for rotational speeds up to 6000 rpm. The measurements have been performed synchronously in the rotating and stationary domains. The analysis of pressure fluctuations at the impeller blade trailing edge, which had significantly larger amplitudes as the pressure fluctuations in the stationary domain, allowed the detection and exploration of stalled channels in the vaned diffuser. This stall may be stationary or rotating with different rotational speeds and number of stalled channels, depending on the relative flow rate and the rotational speed of the pump. The stall yields pressure fluctuations at frequencies which are multiples of the rotational speed of the impeller and generates additional sources of mechanical excitation.

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.

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