Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers

1998 ◽  
Vol 120 (1) ◽  
pp. 179-185 ◽  
Author(s):  
R. Fongang ◽  
J. Colding-Jo̸rgensen ◽  
R. Nordmann
Keyword(s):  
Centrifugal Pump ◽  
Fluid Model ◽  
Hydrodynamic Forces ◽  
Operating Conditions ◽  
Good Prediction ◽  
Single Vortex ◽  
Unsteady Forces ◽  
Fluid Forces ◽  
Rotordynamic Coefficients ◽  
Rotating Impeller

A two-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasi-steady flow model of Colding-Jo̸rengsen (1980) where the impeller was taken as a single vortex source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.

Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers

1996 ◽  
Author(s):  
R. Fongang ◽  
J. Colding-Jørgensen ◽  
R. Nordmann
Keyword(s):  
Centrifugal Pump ◽  
Fluid Model ◽  
Hydrodynamic Forces ◽  
Operating Conditions ◽  
Good Prediction ◽  
Single Vortex ◽  
Unsteady Forces ◽  
Fluid Forces ◽  
Rotordynamic Coefficients ◽  
Rotating Impeller

A 2-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasisteady flow model of Colding-Jørgensen (1980) where the impeller was taken as a single vortex-source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.

scholarly journals The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

1992 ◽  
Author(s):  
A. Guinzburg ◽  
C. E. Brennen ◽  
A. J. Acosta ◽  
T. K. Caughey
Keyword(s):  
Centrifugal Pump ◽  
Guide Vane ◽  
Tangential Force ◽  
Inlet Guide Vane ◽  
Fluid Forces ◽  
Leakage Flows ◽  
Leakage Path ◽  
Inlet Swirl ◽  
Rotating Impeller ◽  
Rotordynamic Forces

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

scholarly journals Unsteady Flow Numerical Simulations on Internal Energy Dissipation for a Low-Head Centrifugal Pump at Part-Load Operating Conditions

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2013 ◽  
Author(s):  
Xiaoran Zhao ◽  
Yongyao Luo ◽  
Zhengwei Wang ◽  
Yexiang Xiao ◽  
François Avellan
Keyword(s):  
Energy Dissipation ◽  
Internal Energy ◽  
Centrifugal Pump ◽  
Flow Separation ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Operating Condition ◽  
Part Load ◽  
Rotating Impeller ◽  
Low Head

Dredge pumps are usually operated at part-load conditions, in which the low-solidity centrifugal impeller could experience large internal energy dissipation, related to flow separation and vortices. In this study, SST k-ω and SAS-SST turbulence models were used, in steady and unsteady simulations, for a low-head centrifugal pump with a three-bladed impeller. The main focus of the present work was to investigate the internal energy dissipation in rotating an impeller at part-load operating conditions, related to flow separation and stall. The unsteady nature of these operating conditions was investigated. Performance experiments and transient wall pressure measurements were conducted for validation. A methodology for internal energy dissipation analysis has been proposed; and the unsteady pressure fluctuations were analyzed in the rotating impeller. The internal power losses in the volute and the impeller were mostly found in the centrifugal pump. The rotating stall phenomenon occurred with flow separation and detachment at the part-load operating condition, leading to a dissipation of the internal energy in the impeller. The rotating impeller experienced pressure fluctuations with low frequencies, at part-load operating conditions, while in the design operating condition only experienced rotating frequency.

scholarly journals An Experimental Study on the Fluid Forces Induced by Rotor-Stator Interaction in a Centrifugal Pump

2003 ◽  
Vol 9 (2) ◽  
pp. 135-144 ◽  
Author(s):  
Shijie Guo ◽  
Hidenobu Okamoto
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Pressure Fluctuations ◽  
Strong Relationship ◽  
Operating Conditions ◽  
Flow Rates ◽  
Fluid Forces ◽  
Large Pressure ◽  
Rotor Stator Interaction ◽  
Frequency Components

The pressure fluctuations and the radial fluid forces acting on the impeller, the pressures in the volute, as well as the vibration of the shaft in a centrifugal pump were measured simultaneously, and their relationship was investigated. Experiments were done for various diffuser vanes, flow rates, and rotating speeds. It was demonstrated that both the blade-pressure fluctuations and the volute static pressures are nonuniform circumferentially (not axisymmetrical) under off-design operating conditions and that the two have a strong relationship. At high flow rates, the blade pressure fluctuations, induced by rotor-stator interactions, are large in areas where the volute static pressure is low. The traveling directions of the rotating pressure waves, the whirling directions of the radial fluid forces, and the most predominant frequency components of both the fluctuations and the forces are discussed, and an equation for predicting them is introduced. It was also noted that large alternating fluid forces are not necessarily associated with large pressure fluctuations. Furthermore, when measuring the radial fluid forces in the rotating frame, other frequency components, in addition to those related to the products of the diffuser vane number and the rotating frequency, may occur due to the circumferential unevenness of the pressure fluctuations on the impeller. These components are predictable.

Numerical Simulation of a Self-Stabilizing Rotor of a Centrifugal Pump

2003 ◽  
Author(s):  
Christian Steinbrecher ◽  
Romuald Skoda ◽  
Rudolf Schilling ◽  
Norbert Mu¨ller ◽  
Alexander Breitenbach ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Hydrodynamic Forces ◽  
Axial Displacement ◽  
Operating Conditions ◽  
Time Dependent ◽  
Navier Stokes ◽  
Axial Position ◽  
Rotating Disc ◽  
Time Step ◽  
Fluid Structure

The goal of this investigation is to contribute to the design of a centrifugal pump that can operate without bearings. This paper presents numerical studies of fluid-structure interactions on a rotating disc that can move axially unrestricted in a housing. This model mimics the gap flow between the rotor and the housing of a centrifugal pump, which stabilizes the rotor. Fluid-structure occur because of hydrodynamic forces that displace the rotor. First the effect responsible for stabilizing the rotor is described in detail. The next section presents the employed 3D Navier-Stokes Computational Fluid Dynamics (CFD) code. Special interest is given to a correct implementation of the Space-Conservation Law, where the time-dependent simulations use moving meshes. The code includes additional modules for grid generation and for calculation of the hydrodynamic forces acting on the rotor surfaces and the resulting displacement of the entire rotor. Newton’s second law is used for the coupling between hydrodynamic forces and resulting axial displacement. Results from stationary simulations are presented and compared with measurements, from the German Heart Center Munich, that show an axial displacement of the rotor results in a hydrodynamic force that pulls the rotor in the opposite direction. Finally, the results from time dependent simulations where the rotor can move unrestricted in axial position are discussed. Here, the influence of the time step is investigated, as well as the influence of geometric parameters and operating conditions.

scholarly journals The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

1993 ◽  
Vol 115 (2) ◽  
pp. 287-293 ◽  
Author(s):  
A. Guinzburg ◽  
C. E. Brennen ◽  
A. J. Acosta ◽  
T. K. Caughey
Keyword(s):  
Centrifugal Pump ◽  
Guide Vane ◽  
Tangential Force ◽  
Inlet Guide Vane ◽  
Fluid Forces ◽  
Leakage Flows ◽  
Leakage Path ◽  
Inlet Swirl ◽  
Rotating Impeller ◽  
Rotordynamic Forces

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrate substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

Calculation of Dynamic Coefficients for a Magnetically Levitated Artificial Heart Pump Using a CFD Approach

2008 ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Timothy W. Dimond
Keyword(s):  
Artificial Heart ◽  
Operating Conditions ◽  
Magnetic Suspension ◽  
Magnetic Bearings ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Fluid Medium ◽  
Fluid Forces ◽  
Operational Life ◽  
Rotating Impeller

The artificial heart community acknowledges the 3rd generation Ventricular Assist Devices (VADs) as the leading technology in mechanical blood pump development. This category consists of rotary pumps with no mechanical or fluid bearings in contact with the fluid medium, usually magnetic or noncontacting hydrodynamic bearings. A magnetic suspension prevents the rotating impeller from contacting the pump’s internal surfaces and reduces regions of stagnant and high shear flow that normally surround a fluid or mechanical bearing. Magnetic bearings have no moving parts in contact and thus do not wear over time; this generally lengthens the operational life of the pumps as compared to those supported by conventional bearings. Employing this 3rd generation technology, the University of Virginia has been developing a ventricular assist device (LifeFlow) with a rotor that is suspended entirely by magnetic bearings. In order to perform the stability analysis, the hydrodynamic effects of the rotating impeller should be included in the calculation. This study describes the method to calculate the stiffness, damping, and mass coefficients, based on the CFD prediction of radial fluid forces exerted on the impeller due to its eccentric position inside the pump housing over a range of operating conditions. In consideration of the suspension design, the fluid forces exerted on the levitated axial impeller were estimated using CFD such that any fluid perturbations would be accounted for and counterbalanced during the suspension and motor design phase.

scholarly journals Transfer Learning with Deep Recurrent Neural Networks for Remaining Useful Life Estimation

2018 ◽  
Vol 8 (12) ◽  
pp. 2416 ◽  
Author(s):  
Ansi Zhang ◽  
Honglei Wang ◽  
Shaobo Li ◽  
Yuxin Cui ◽  
Zhonghao Liu ◽  
...  
Keyword(s):  
Neural Networks ◽  
Transfer Learning ◽  
Recurrent Neural Networks ◽  
Prediction Models ◽  
Learning Algorithm ◽  
Remaining Useful Life ◽  
Operating Conditions ◽  
Training Data ◽  
Good Prediction ◽  
Useful Life

Prognostics, such as remaining useful life (RUL) prediction, is a crucial task in condition-based maintenance. A major challenge in data-driven prognostics is the difficulty of obtaining a sufficient number of samples of failure progression. However, for traditional machine learning methods and deep neural networks, enough training data is a prerequisite to train good prediction models. In this work, we proposed a transfer learning algorithm based on Bi-directional Long Short-Term Memory (BLSTM) recurrent neural networks for RUL estimation, in which the models can be first trained on different but related datasets and then fine-tuned by the target dataset. Extensive experimental results show that transfer learning can in general improve the prediction models on the dataset with a small number of samples. There is one exception that when transferring from multi-type operating conditions to single operating conditions, transfer learning led to a worse result.

Experimental and Numerical Investigation of Centrifugal Pump Performance When Handling Viscous Fluids

2005 ◽  
Author(s):  
M. H. Shojaee Fard ◽  
M. B. Ehghaghi ◽  
F. A. Boyaghchi
Keyword(s):  
Soviet Union ◽  
Centrifugal Pump ◽  
Turbulent Flows ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Viscous Fluids ◽  
Test Bed ◽  
Flow Process ◽  
Pump Performance

On the test bed of centrifugal pump, the centrifugal pump performance has been investigated using water and viscous oil as Newtonian fluids, whose kinematic viscosities are 1 × 10−6, 43 × 10−6 and 62 × 10−6 m2/s, respectively. Also, the finite volume method is used to model the three dimensional viscous fluids for different operating conditions. For these numerical simulations the SIMPLEC algorithm is used for solving governing equations of incompressible viscous/turbulent flows through the pump. The κ-ε turbulence model is adopted to describe the turbulent flow process. These simulations have been made with a steady calculation and using the multiple reference frame (MRF) technique to take into account the impeller-volute interaction. Numerical results are compared with the experimental characteristic curve for each viscous fluid. The data obtained allow the analysis of the main phenomena existent in this pump, such as: head, efficiency, power and pressure field changes for different operating conditions. Also, the correction factors for oils are obtained from the experimental for part loading (PL), best efficiency point (BEP) and over loading (OL) and the results are compared with proposed factors by American Hydraulic Institute (HIS) and Soviet Union (USSR). The comparisons between the numerical and experimental results show a good agreement.

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