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 Flow and windage due to bolts on a rotating disc

2016 ◽  
Vol 231 (15) ◽  
pp. 2925-2941
Author(s):  
Sulfickerali Noor Mohamed ◽  
John Chew ◽  
Nick Hills
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Rotating Disc ◽  
Rotating Machine ◽  
Flow Features ◽  
Rotor Surface ◽  
Dynamics Simulations ◽  
Cooling Air

The cooling air in a rotating machine is subject to windage as it passes over the rotor surface, particularly for cases where nonaxisymmetric features such as boltheads are encountered. The ability to accurately predict windage can help reduce the quantity of cooling air required, resulting in increased efficiency. Previous work has shown that the steady computational fluid dynamics solutions can give reasonable predictions for the effects of bolts on disc moment for a rotor–stator cavity with throughflow but flow velocities and disc temperature are not well predicted. Large fluctuations in velocities have been observed experimentally in some cases. Time-dependent computational fluid dynamics simulations reported here bring to light the unsteady nature of the flow. Unsteady Reynolds-averaged Navier–Stokes calculations for 120° and 360° models of the rotor–stator cavity with 9 and 18 bolts were performed in order to better understand the flow physics. Although the rotor–stator cavity with bolts is geometrically steady in the rotating frame of reference, it was found that the bolts generate unsteadiness which creates time-dependent rotating flow features within the cavity. At low throughflow conditions, the unsteady flow significantly increases the average disc temperature.

Numerical Research of the Effect of the Outlet Diameter of Diffuser on the Performance and the Radial Force in a Single-Stage Centrifugal Pump

2014 ◽  
Author(s):  
Jiang Wei ◽  
Li Guojun ◽  
Liu Pengfei ◽  
Zhang Lisheng ◽  
Qing Hongyang
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Numerical Results ◽  
Operating Conditions ◽  
Single Stage ◽  
Navier Stokes ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Vaned Diffuser ◽  
Unsteady Numerical Simulation

In this paper, a single-stage pump with diffuser vanes of different outlet diameters has been investigated both numerically and experimentally. The influence of the diffuser vane outlet diameter on pump hydraulic performance and on the radial force of the impeller is explored. Pumps equipped with three different diffusers but with impellers and volutes of the same parameters were simulated by 3D Navier-Stokes solver ANSYS-FLUENT in order to study the effect of the outlet diameter of vaned diffuser on performance of the centrifugal pump. Structured grids of high quality were applied on the whole computational domain. Experimental results were acquired by prototype experiments and were then compared with the numerical results. Both experimental and numerical results show that the performance of a pump with a diffuser of smaller outlet diameter is better than of bigger outlet diameter under all operating conditions. The radial force imposed on the impeller obtained by unsteady numerical simulation was analyzed. The results also indicated that an appropriate decrease in the outlet diameter of the diffuser vane could increase the radial force.

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 Three-Dimensional Simulation of Fluid–Structure Interaction Problems Using Monolithic Semi-Implicit Algorithm

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 94 ◽  
Author(s):  
Cornel Marius Murea
Keyword(s):  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dimensional Simulation ◽  
Updated Lagrangian

A monolithic semi-implicit method is presented for three-dimensional simulation of fluid–structure interaction problems. The updated Lagrangian framework is used for the structure modeled by linear elasticity equation and, for the fluid governed by the Navier–Stokes equations, we employ the Arbitrary Lagrangian Eulerian method. We use a global mesh for the fluid–structure domain where the fluid–structure interface is an interior boundary. The continuity of velocity at the interface is automatically satisfied by using globally continuous finite element for the velocity in the fluid–structure mesh. The method is fast because we solve only a linear system at each time step. Three-dimensional numerical tests are presented.

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.

scholarly journals Effect of Dynamic Stress on Heavy Duty Centrifugal Pump Assembly through Fluid Structure Interaction.

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1655-1659
Keyword(s):  
Centrifugal Pump ◽  
Dynamic Stress ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Current ◽  
Fluid Structure Interactions ◽  
Heavy Duty ◽  
Dynamic Stresses ◽  
Fluid Structure ◽  
Pump Assembly

The objective of the project is to reduce the vibration and fatigue in rotor of the centrifugal pump based on fluid structure interactions, when it rotates by the momentum of water current at different flow rate and to arrive at optimum operating conditions and perform structural analysis to determine deflection and frequency by using ANSYS 16.2.dynamic stresses are predicted at various nodal position, this would lead to suggest the method to reduce the frequency due to vibration.Computational fluid dynamics (CFD) study using Ansys 16.2 has been carried out to accomplish the objective of the work.

A Numerical Approach to Unstalled and Stalled Flutter Phenomena in Turbomachinery Cascades

1997 ◽  
Author(s):  
Stefan Weber ◽  
Hannes Benetschik ◽  
Dieter Peitsch ◽  
Heinz E. Gallus
Keyword(s):  
Stokes Equations ◽  
Turbine Blades ◽  
Numerical Approach ◽  
Implicit Scheme ◽  
Time Dependent ◽  
Navier Stokes ◽  
Tvd Scheme ◽  
Compressor Cascade ◽  
Viscous Effects ◽  
Time Step

During the design process of compressor and turbine blades the investigation of flutter phenomena becomes increasingly important since higher load and better efficiency are desired. As an improvement on the numerical analysis and prediction of unsteady flow through turbomachine cascades with vibrating blades a time accurate Navier Stokes code for S1-stream surfaces SAFES1 is presented within the scope of this paper. To validate the code, numerical results for sub- and transonic test cases of a turbine and a compressor cascade are compared with experimental data. Their good agreement and comparison with Euler calculations show the necessity to take into account viscous effects. To cope with shock waves and areas of separation in laminar or turbulent flow, the fully non linearized Navier Stokes equations are solved using an algebraic turbulence model by Baldwin and Lomax. An approximative upwind flux difference splitting scheme suggested by Roe is implemented. Third order spatial accuracy can be achieved by the MUSCL technique in conjunction with a TVD scheme and a flux limiter by van Albada. By applying either an explicit or an implicit scheme the algorithm can give second order temporal accuracy. The implicit scheme exactly describes the time dependent solution by following a Newton subiteration for every time step. The blades are discretized in a single passage by a C- or O-type grid. The harmonic motion of the blades is bending or torsion or both simultaneously in a non-rotating or rotating frame of reference. For the chosen mode of oscillation the time dependent axial and circumferential blade forces are determined as well as the resulting moment and damping coefficient. To handle a phaseshift between the motion of the blades a direct store method is used. For the unsteady grid movement a fast grid generation is performed in the core region.

Numerical Invertigation of Water Entry of a Subsea Module With Deflated Cavity Shells

2020 ◽  
Author(s):  
Yingfei Zan ◽  
Ruinan Guo ◽  
Lihao Yuan ◽  
Fuxiang Huang ◽  
Dongchun Kang
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Flow Field ◽  
Stokes Equations ◽  
Water Entry ◽  
Hydrodynamic Forces ◽  
Operating Conditions ◽  
Frame Structure ◽  
Navier Stokes ◽  
Navier Stokes Equations

Abstract In subsea installation operations, the hydrodynamic forces on the subsea module are important considerations when designing the structure and choosing slings. In this paper, the hydrodynamic forces and flow field of a subsea module with deflated cavity shells during forced water entry operation were investigated numerically. The numerical simulation was carried out based on Reynolds-averaged Navier–Stokes equations, with a constant lowering velocity of the module. The results of the numerical simulation were validated by experimental data and they showed good agreement. The relationship between hydrodynamic forces and draft was presented. Furthermore, the slamming positions, free surface variation, pressure variation in deflated cavity shells, slamming coefficient and the influence of holes were studied based on flow field scenes. It was found that the hydrodynamic forces varied with draft non-linearly. Moreover, the change of draft altered the form of the free surface due to the complex steel frame structure of deflated cavity shells. The present study can be further extended to assess the operating conditions of lifting operations and to advise on the design of the subsea module.

THE TEMPERATURE RESPONSE OF COMPACT TUBULAR MICROALGAE PHOTOBIOREACTORS

2009 ◽  
Vol 8 (2) ◽  
pp. 50
Author(s):  
R. L. L. Ribeiro ◽  
A. B. Mariano ◽  
E. Dilay ◽  
J. A. Souza ◽  
J. C. Ordonez ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Growth Temperature ◽  
Control Volume ◽  
Operating Conditions ◽  
Time Dependent ◽  
Solution Temperature ◽  
Transient Temperature ◽  
Physical Domain ◽  
Empirical Correlations ◽  
Time Step

A mathematical and computational modeling of a photobioreactor for the determination of the transient temperature behavior in compact tubular microalgae photobioreactors is presented. The model combines theoretical concepts of thermodynamics with classical theoretical and empirical correlations of Fluid Mechanics and Heat Transfer. The physical domain is discretized with the Volume Element Model (VEM) through which the physical system (reactor pipes) is divided into lumped volumes, such that only one time dependent ordinary differential equation, ODE, results for temperature, based on the first law of thermodynamics. The energetic interactions between the volumes are established through heat transfer empirical correlations for convection, conduction and radiation. Within this context, the main goal of this study is to present a numerical methodology to calculate the mixture (algae + water + nutrients) temperature inside the compact photobioreactor. A pilot plant is under construction, in the Center of Research and Development for Self-Sustainable Energy (NPDEAS), located at UFPR, and the experimental data obtained from this research unit will be used to validate the present numerical solution. Temperature is one of the most important parameters to be controlled in microalgae growth. Microalgae that are cultivated outside their growth temperature range may have a low growth rate or die. For this reason a numerical simulation of the system based on the operating conditions and environmental factors is desirable, in order to predict the transient algae growth temperature distribution along the reactor pipes. The VEM creates an “artificial” spatial dependence in the system or process under analysis by dividing the space (physical domain) into smaller sub domains, namely Volume Elements (VE). Each VE interacts with its neighbors by exchanging energy and/or mass. Thus, each VE is treated as a control volume from classical thermodynamics, i.e., with uniform properties and exchanging mass and energy with its neighbors. The problem is then formulated with the energy equation applied to the fluid VE and to the wall VE. These equations form a system of time dependent ODE’s, which are not dependent on space, therefore eliminating the need for the solution of a system of partial differential equations, PDE’s, depend on time and space, as is the case of traditional numerical methods (e.g., finite element, finite volume and finite differences). The resulting ODE’s were solved using a fourth order Runge-Kutta method with adaptive time step.

Research on Improving the Dynamic Performance of Centrifugal Pumps With Twisted Gap Drainage Blades

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Zheng-Chuan Zhang ◽  
Hong-Xun Chen ◽  
Zheng Ma ◽  
Jian-Wu He ◽  
Hui Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Dynamic Characteristics ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Centrifugal Pumps ◽  
Practical Applications

Through numerical simulation and experiments analysis, it is indicated that the hydraulic and anticavitation performance of a centrifugal pump with twisted gap drainage blades based on flow control theory can be significantly improved under certain operating conditions. In order to introduce the technology of gap drainage to practical applications, we put forward the parameter formulas of the twisted gap drainage blade to design three-dimensional new type blade, which are also proved to be effective for enhancing the dynamic characteristics of the centrifugal pump. Furthermore, a practical centrifugal pump is redesigned to be a twisted gap drainage impeller with the same structure size as the original impeller, and the nonlinear hybrid Reynolds-averaged Navier–Stokes (RANS)/large eddy simulation (LES) method is employed to simulate the hydraulic dynamic characteristics. Numerical simulation results show that the hydraulic performance and dynamic characteristics of the redesigned impeller centrifugal pump are significantly enhanced. In experiments, the twisted gap drainage blades structure not only remarkably improves the hydraulic performance and the pressure pulsation characteristics of the centrifugal pump but also reduces the vibration intensity.

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