Numerical Simulation of Inner Flow in a Double Blades Pump Based on OpenFOAM and its PIV Verification

2012 ◽  
Author(s):  
Yun Ren ◽  
Houlin Liu ◽  
Kai Wang ◽  
Minggao Tan ◽  
Denghao Wu ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Energy Performance ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Complex Flow ◽  
Unstable Flow ◽  
Software Packages ◽  
Flow Phenomena ◽  
Particle Imaging

The presence of unstable flow phenomena may significantly alter the flow pattern and characteristics of centrifugal pumps; that is, the unstable flows may seriously deteriorate the pumps performance. In this paper, considering the high cost of running license fees and not available with all the computing resources, a high quality Open Source CFD simulation platform like OpenFOAM instead of commercial software packages is adopted. Furthermore, the required capability such as GGI is added and boundary conditions are specialized to better simulate complex flow behavior through rotor-stator components in a double blades pump, whose specific speed is 115.6. In order to disclose the characteristics completely, six research schemes are developed and are now presented in this paper. The ratios (Q/Qd) of the flow rate are 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, respectively. The task mainly focuses on the comparison of energy performance under different operating conditions between numerical calculations and experiments, the analysis of the inner flow in the impeller and the comparison of the velocity field in the impeller mid-height between simulation data and the Particle Imaging Velocimetry (PIV) experimental data. The results show that good agreements are found both in terms of the energy performance with experimental results and computed velocities with the PIV data, but improvements can be made.

Granular Flow Modeling and Simulation Using a Dynamic Finite Element Method

2007 ◽  
Author(s):  
M. A. Kabir ◽  
C. Fred Higgs ◽  
Michael R. Lovell
Keyword(s):  
Finite Element ◽  
Modeling And Simulation ◽  
Granular Flow ◽  
Flow Behavior ◽  
Food Service ◽  
Complex Nature ◽  
Complex Flow ◽  
Dual Nature ◽  
Simulation Techniques ◽  
Flow Phenomena

Granular flow behavior is of fundamental interest to the engineering and scientific community because of the prevalence of these flows in the pharmaceutical, agricultural, food service, and powder manufacturing industries. Granular materials exhibit very complex behavior, oftentimes acting as solids and at other times as fluids. This dual nature leads to very complex and rich behavior, which is not yet well understood. Therefore, the present investigation introduces a new technique that can potentially be used to unveil the mystery of granular flow phenomena. To this end, advanced finite element modeling and simulation techniques have been applied to the study of the complex nature of granular flow. More specifically, the explicit dynamic code LS-DYNA has been utilized to gain an understanding of the complex flow nature and collision stresses of granules in a shear cell.

Investigation of Brush Seal Flow Characteristics Using Bulk Porous Medium Approach

2005 ◽  
Vol 127 (1) ◽  
pp. 136-144 ◽  
Author(s):  
Yahya Dogu
Keyword(s):  
Porous Medium ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Operating Conditions ◽  
Force Balance ◽  
Complex Flow ◽  
Blow Down ◽  
Permeability Coefficients ◽  
Backing Plate ◽  
Brush Seal

The flow behavior through a brush seal has been investigated by developing a flow analysis procedure with a porous medium approach. In order to increase the brush seal performance and use at more severe operating conditions, the complex flow in the bristle pack has become the major concern affecting seal features such as blow-down, hang-up, hysteresis, and bristle flutter. In this study, an axisymmetric CFD model is employed to calibrate anisotropic permeability coefficients for the bristle pack based on available experimental data: leakage, axial pressure on the rotor surface, and radial pressure on the backing plate. A simplified form of the force balance equation is introduced for the flow in the porous bristle pack. Different sets of permeability coefficients are defined for the fence height region below the seal backing plate and the upper region of the seal to correlate the different physical structures and behavior of these regions during operation. The upper region is subject to more stiffening due to backing plate support while the fence height region is free to spread and bend in the axial direction. It is found that flow resistance for the upper region should be 20% higher than the fence height region in order to match the experimental pressure within the bristle pack. Analysis results prove that the brush seal is well represented as a porous medium with this approach. Based on the model developed, characteristic flow and pressure fields in the entire bristle pack have been explored.

CFD Simulation of Wall-Bounded Laminar Flow Through Screens: Part II — Mixing Characterization

2020 ◽  
Author(s):  
W. Abou Hweij ◽  
F. Azizi
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Particle Method ◽  
Immiscible Fluids ◽  
Laminar Flows ◽  
Operating Conditions ◽  
Static Mixers ◽  
Flow Through ◽  
Dispersive Mixing ◽  
Lagrangian Particle Method

Abstract This paper characterizes the mixing behavior of laminar flows within a circular pipe equipped with plain woven meshes or screens, acting as static mixers. In this quest, their performance was numerically investigated using the Lagrangian particle method in a commercial CFD solver, whereby the effect of changing the screen geometry, number of screens, inter-screen spacing, and operating conditions were considered. Mixing was addressed from a distributive and dispersive perspectives using both qualitative and quantitative descriptions. The distributive mixing indicated that a central injection of a single fluid should be coupled with a short inter-screen spacing to better spread the particles and enhance mixing as opposed to a larger inter-screen spacing. On the contrary, the mixing of two immiscible fluids of similar properties reveal that a large inter-screen spacing is recommended. From a dispersive mixing perspective, extensional efficiency contours revealed that the fluid would undergo all three modes of flow behavior, each of which dominating a certain region depending on the location with respect to the screen. Finally, it was interesting to find that a coarser screen geometry consistently outperformed finer screens in spreading and mixing the particles.

Heat Coupling of Gasoline Upgrading and Fluid Catalytic Cracking Processes

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Xingying Lan ◽  
Chunming Xu ◽  
Gang Wang ◽  
Jian Chang ◽  
Chunxi Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Balance ◽  
Cfd Simulation ◽  
Flow Behavior ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Regeneration System ◽  
Fcc Gasoline ◽  
Fcc Catalysts ◽  
The Heat Balance

Heat supplement is necessary for FCC gasoline upgrading processes to keep the heat balance of reaction-regeneration system, while excess heat would be removed in FCC process due to the processing of heavy feedstock. Combining gasoline upgrading processes with FCC process can realize the heat coupling so as to achieve the maximum energy utilization. In this paper, the heat balance calculations of a commercial FCC unit and a FCC gasoline aromatization process were carried out, and the feasibility as well as the way to accomplish the heat coupling for the two processes was investigated. The results showed that the coked aromatization catalysts could be heated to the desired temperature by the direct contact with the hot regenerated FCC catalysts. The pilot experiment and CFD simulation was carried out to investigate the flow behavior and heat transfer of the direct coupling system of FCC process and FCC gasoline aromatization process. The results indicated that the well-mixing and efficient heat transfer between FCC catalysts and aromatization catalysts, as well as the sufficient regeneration of aromatization catalysts, could be achieved at appropriate operating conditions.

Simulation of Wall Pressure Fluctuations on Simplified Automobile Shapes Using a Lattice Based Method

2005 ◽  
Author(s):  
Sivapalan Senthooran ◽  
Bernd Crouse ◽  
Ganapathi Balasubramanian ◽  
David Freed ◽  
Swen Noelting ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Scheme ◽  
Cfd Simulation ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Complex Flow ◽  
Wall Pressure Fluctuations ◽  
Flow Phenomena ◽  
High Reynolds ◽  
Rng Turbulence Model

A comparison of experimental data and CFD simulation results of wall pressure fluctuations on simplified geometries that generate flow structures similar to an automobile are presented. The numerical results have been obtained using the commercial software PowerFLOW 3.4p4a. The simulation kernel of this software is based on the numerical scheme known as the Lattice Boltzmann Method (LBM), combined with an RNG turbulence model. This scheme accurately captures time-dependent aerodynamic behavior of high Reynolds number flows over complex geometries, together with the acoustics. The geometries considered for this study represent the green house and the side mirror of a car. Spectral analysis is performed on the simulation data and the results are compared to the experimental data. This comparison provides good correlation between the simulation and experiment, and demonstrates the capability of this numerical scheme in predicting turbulent fluctuations due to complex flow phenomena.

Numerical Analysis of Centrifugal Pumps Running in Turbine Mode Under Dynamic Operating Conditions

2017 ◽  
Author(s):  
Vincenzo De Rose ◽  
Francesca Martelli ◽  
Massimo Milani ◽  
Luca Montorsi
Keyword(s):  
Cfd Simulation ◽  
Energy Conversion Efficiency ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Pump Operation ◽  
Electric Generator ◽  
Reverse Mode ◽  
Hydropower Plants ◽  
Dynamic Operating ◽  
Turbine Mode

The use of pumps as turbines (PAT) has gained importance in the recent years as a possible alternative to specifically developed turbine for mini/micro hydropower plants. The use of production pump for hydropower generation reduces the capital cost of the plant but the energy conversion efficiency can be remarkably lower. The paper analyses the performance of a production centrifugal pump running both in direct and reverse mode. The analysis calculates theoretically the behavior of the PAT under the best efficiency point and extends the investigation to other operating points using both a combined theoretical approach and CFD simulation under dynamic conditions. The effects of possible modifications to the initial design of the pump are investigated when running in turbine mode and their influence on the standard pump operation is also determined. Numerical simulation demonstrates that the impeller trimming leads to improvement in the PAT efficiency in some operating conditions. Conversely, the rotational speeds close to the values typical for the electric generator reduce the PAT performance. Finally, the modification of the impeller geometry at the turbine inlet increases the PAT efficiency but lowers the performance of the machine when running in pump mode.

Complex Flow Dynamics in Dense Granular Flows—Part II: Simulations

2006 ◽  
Vol 74 (4) ◽  
pp. 691-702 ◽  
Author(s):  
Piroz Zamankhan ◽  
Jun Huang
Keyword(s):  
Granular Flow ◽  
Large Scale ◽  
Flow Behavior ◽  
Granular Flows ◽  
Industrial Applications ◽  
Complex Flow ◽  
Flow Phenomena ◽  
Newton’S Cradle ◽  
Large Scale Simulations ◽  
Dense Granular Flows

By applying a methodology useful for analysis of complex fluids based on a synergistic combination of experiments, computer simulations, and theoretical investigation, a model was built to investigate the fluid dynamics of granular flows in an intermediate regime, where both collisional and frictional interactions may affect the flow behavior. In Part I, experiments were described using a modified Newton’s Cradle device to obtain values for the viscous damping coefficient, which were scarce in the literature. This paper discusses detailed simulations of frictional interactions between the grains during a binary collision by employing a numerical model based on finite element methods. Numerical results are presented of slipping, and sticking motions of a first grain over the second one. The key was to utilize the results of the aforementioned comprehensive model in order to provide a simplified model for accurate and efficient granular-flow simulations with which the qualitative trends observed in the experiments can be captured. To validate the model, large scale simulations were performed for the specific case of granular flow in a rapidly spinning bucket. The model was able to reproduce experimentally observed flow phenomena, such as the formation of a depression in the center of the bucket spinning at high frequency of 100rad/s. This agreement suggests that the model may be a useful tool for the prediction of dense granular flows in industrial applications, but highlights the need for further experimental investigation of granular flows in order to refine the model.

Investigation of Brush Seal Flow Characteristics Using Bulk Porous Medium Approach

2003 ◽  
Author(s):  
Yahya Dogu
Keyword(s):  
Porous Medium ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Operating Conditions ◽  
Force Balance ◽  
Complex Flow ◽  
Blow Down ◽  
Permeability Coefficients ◽  
Backing Plate ◽  
Brush Seal

The flow behavior through a brush seal has been investigated by developing a flow analysis procedure with a porous medium approach. In order to increase the brush seal performance and use at more severe operating conditions, the complex flow in the bristle pack has become the major concern affecting seal features such as blow-down, hang-up, hysteresis and bristle flutter. In this study, an axi-symmetric CFD model is employed to calibrate anisotropic permeability coefficients for the bristle pack based on available experimental data; leakage, axial pressure on the rotor surface and radial pressure on the backing plate. A simplified form of the force balance equation is introduced for the flow in the porous bristle pack. Different sets of permeability coefficients are defined for fence height region below the seal backing plate and the upper region of the seal to correlate the different physical structures and behavior of these regions during operation. The upper region is subject to more stiffening due to backing plate support while fence height region is free to spread and bend in the axial direction. It is found that flow resistance for upper region should be 20% higher than fence height region in order to match the experimental pressure within the bristle pack. Analysis results prove that the brush seal is well represented as a porous medium with this approach. Based on the model developed, characteristic flow and pressure fields in the entire bristle pack have been explored.

Flow Pattern Evolution and Energy Decomposition of Flows at Different Operating Conditions in a Hydrodynamic Torque Converter

2016 ◽  
Author(s):  
Wei Wei ◽  
Mingxing Huang ◽  
Yu Li ◽  
Qingdong Yan
Keyword(s):  
Vortex Structure ◽  
Velocity Vector ◽  
Power Transmission ◽  
Flow Behavior ◽  
Internal Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Energy Decomposition ◽  
Complex Flow

Power loss and flow blockage in turbomachinery such as hydrodynamic torque converter are usually caused by jet flow, second flow and flow separation. In this paper, the velocity vector and the pressure distribution of the internal flow field in hydrodynamic torque converter were reduced by the method of the Proper Orthogonal Decomposition (POD) to find the main flow structures and the energy decomposition in the passages of pump, turbine and stator. In order to find their evolutionary processes and energy decompositions, oil flow visualizations were conducted at different speed ratios from 0 to 0.8, including stall condition and design operating condition. The results showed that the first few modes containing the majority of energy could provide enough accuracy to predict flow behavior and flow structure in flow passages. Especially when the energy percentage of the first mode was majority, its vortex structures could be recognized easily. But the flow patterns of other modes were different from each other and they made the flow more turbulent and complex, which increases the energy loss in the process of power transmission. Besides that, the change of pressure gradient had a direct influence to velocity vector. The results also indicated that the observed fluid pattern of vortex structure became extensive while the influence of secondary flow decreased in the flow passage of pump with the increase of speed ratio. But the situation is just reversed in turbine, that is, the vortex disappeared gradually and the irregular turbulent flow appeared as the increase of speed ratio. In stator, the vortex structure emerged gradually when the speed ratio increased. So the method of snapshots is a very useful way to analyze the complex flow flied in depth and to predict the trend of development.

Experimental and Numerical Analysis of Pressure Pulsations and Mechanical Deformations in a Centrifugal Pump Impeller

2011 ◽  
Author(s):  
Stefan Berten ◽  
Sebastian Hentschel ◽  
Karin Kieselbach ◽  
Philippe Dupont
Keyword(s):  
Boundary Conditions ◽  
Flow Behavior ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Pressure Waves ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
Load Pressure ◽  
Part Load

Deformations, mechanical stresses and vibrations in centrifugal pumps are the result of pressure fluctuations, which are acting as excitation forces. When a pump operates at its optimum, the pressure pulsations are at minimum, but for a pump operating in part-load, pressure pulsations increase and subsequent vibration and deformation levels increase. In a recent experimental research, the pressure pulsations and the resulting structural stresses in the last stage impeller of a multistage pump have experimentally investigated for different operating conditions [1]. The experimental investigations have been complemented by transient numerical simulations using a commercial CFD code and structural analysis using the pressure pulsations resulting from the CFD code as boundary conditions. In the present study, a validation of these CFD and FEM simulations is presented. The analysis has been performed in three steps. In the first step, the transient CFD results for different load cases are analyzed and compared with the experimental results in order to evaluate the CFD simulations. In the second step the time domain pressure pulsation data are post-treated and decomposed into a series of rotating pressure waves. These pressure waves are then applied as boundary conditions to an FEM model and one full impeller revolution is simulated as steady calculations for 72 angular positions. The pressure pulsations in the best efficiency point are regularly distributed in space and time and dominated by rotor-stator-interaction. For part-load operation, the pressure distribution becomes more and more unsteady. The CFD results for part load exhibit stationary stall in the diffuser for a flow rate relative to best efficiency point of q* = 0.9 and unsteady stall behavior for a q* = 0.8. While the numerical CFD results agree well with experimental data for q* = 1 and q* = 0.9, at lower part load (q* = 0.8) the CFD didn’t reproduce the experimentally observed flow behavior, especially the rotating stall. The FEM results at design conditions show relatively low tangential stresses at the impeller outlet, which agree well with the measured deformations and stresses.

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