Rational Technique for Multistage Centrifugal Pump CFD-Modeling

2015 ◽  
Author(s):  
Vasiliy M. Zubanov ◽  
Leonid S. Shabliy ◽  
Alexander V. Krivcov
Keyword(s):  
Computational Cost ◽  
Turbulence Models ◽  
Cfd Modeling ◽  
Radial Load ◽  
Cfd Model ◽  
Multistage Centrifugal Pump ◽  
Model Configuration ◽  
Flow Features ◽  
Flow Through ◽  
Multistage Pump

This article reports CFD-modeling technique of flow through a kerosene pump and suggests appropriate CFD tools, model configuration, types of boundary conditions, turbulence models and meshing technique. The flow features were analyzed and error of the CFD-model was estimated. The CFD results were compared with experimental results. The final CFD-model, which was also verified with the impeller radial load estimation, shows that the technique produces sufficient accurate results with less computational cost. The technique can be used for the design optimization of a multistage pump.

Nonlinear Versus Linear Stress-Strain Relations in Engine Turbulence Modeling Under Swirl and Squish Flow Conditions

2004 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Stefano d’Ambrosio
Keyword(s):  
Turbulence Modeling ◽  
Swirling Flow ◽  
Nonlinear Models ◽  
Local Equilibrium ◽  
Computational Cost ◽  
Turbulence Models ◽  
Stress Strain ◽  
Accuracy Order ◽  
Wall Boundary Conditions ◽  
Flow Features

A general form of the stress-strain constitutive relation was introduced for the application of two nonlinear k-ε turbulence models, namely, the ARS model of Gatski and Speziale ([1]) and the Cubic model of Lien et al. ([2]), to the numerical analysis of flow fields in a test engine with flat-piston and bowl-in-piston arrangements, under swirling or no-swirling flow motored conditions. The model capabilities in capturing turbulent flow features were compared to those of the upgraded linear RNG k-ε model which was previously indicated as a good compromise between accuracy and computational cost ([3]). Evaluations were made on the basis of the predicted flow evolution throughout the whole engine cycle, as well as of the comparison between numerical and experimental results. Furthermore, the effect of the stress-strain relationship on the predicted averaged turbulence quantities and anisotropy invariant values were examined, in addition to the sensitivity of the nonlinear models to the mesh quality. Finally, prospects concerning possible improvements of turbulence Eddy Viscosity Models (EVM) were presented. The predictions were made by a newly developed CFD code embedding various accuracy-order finite-volume discretization schemes. Modified wall boundary conditions with respect to the conventional logarithmic-function approach were used, so as to give negligible importance to the local equilibrium hypothesis.

Development of Large-Eddy Simulation for Vehicle Aerodynamics

2002 ◽  
Author(s):  
S. Krajnovic ◽  
L. Davidson
Keyword(s):  
Large Eddy Simulation ◽  
Computational Cost ◽  
Turbulence Models ◽  
Quantitative Prediction ◽  
Eddy Simulation ◽  
Aerodynamic Properties ◽  
Lower Reynolds Number ◽  
Large Eddy ◽  
Flow Features ◽  
Vehicle Aerodynamics

The feasibility of use of large-eddy simulation (LES) in external vehicle aerodynamics is investigated. The computational cost needed for LES of the full size car at road conditions is beyond the capability of the computers in the near future (Krajnovic´ (2002)). Since LES cannot be used for quantitative prediction of this flow, i.e. obtaining the aerodynamic forces and moments, an alternative use of this technique is suggested that can enhance the understanding of the flow around a car. It is found that making LES of the flow around simplified car-like shapes at lower Reynolds number can increase our knowledge of the flow around a car. Two simulations are made, one of the flow around a cube and the other of the flow around a simplified bus. The former simulation proved that LES with relatively coarse resolution and simple inlet boundary condition can provide accurate results. The latter simulation resulted in flow in agreement with experimental observations and displayed some flow features that were not observed in experiments or steady simulations of such flows. This simulation gave us possibility to study the transient mechanisms that are responsible for the aerodynamic properties of a car. The knowledge gained from this simulation can be used by the stylist to tune the aerodynamics of the car’s design but also by the CFD specialists to improve the turbulence models.

scholarly journals Validation and assessment of different RANS turbulence models for simulating turbulent flow through an orifice plate

2021 ◽  
Vol 1201 (1) ◽  
pp. 012019
Author(s):  
A P Jurga ◽  
M J Janocha ◽  
G Yin ◽  
K E T Giljarhus ◽  
M C Ong
Keyword(s):  
Turbulent Flow ◽  
Turbulence Models ◽  
Diameter Ratio ◽  
Orifice Plate ◽  
Pipe Diameter ◽  
Navier Stokes ◽  
Orifice Diameter ◽  
Flow Features ◽  
Rans Turbulence Models ◽  
Flow Through

Abstract In the present study, numerical simulations using different Reynolds-Averaged Navier–Stokes (RANS) turbulence models are carried out to investigate the turbulent flow through the orifice plate at Reynolds number (Re) of 23000. The orifice thickness to pipe diameter ratio (t) and the orifice diameter to pipe diameter ratio (β) are fixed and equal to 0.1 and 0.5, respectively. The objective is to evaluate the behaviour of various RANS models with respect to the relevant flow parameters such as the pressure drop, velocity distributions and turbulence intensity profiles in the pipe by comparing the results with available published experimental data. The following turbulence models are studied: the k – ε, the k – ε Low Re, the k – ε RNG, the k – ε Realizable, the k – ω SST, the γ – SST, the EARSM and the k – ε Cubic models. It is found that based on the validation study of the flow through the orifice plate, the following models are in good agreement with experimental measurements: the k – ω SST, the γ – SST and the EARSM. They show a better performance than the k – ε model family in predicting the flow features which are important for the orifice flowmeter design.

scholarly journals Numerical Modeling of Flow Over a Rectangular Broad-Crested Weir with a Sloped Upstream Face

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1663 ◽  
Author(s):  
Lei Jiang ◽  
Mingjun Diao ◽  
Haomiao Sun ◽  
Yu Ren
Keyword(s):  
Numerical Simulations ◽  
Discharge Coefficient ◽  
Separation Zone ◽  
Turbulence Models ◽  
Numerical Results ◽  
Upstream Face ◽  
Flow Conditions ◽  
Flow Features ◽  
The Mean ◽  
Absolute Percent Error

The objective of this study was to evaluate the effect of the upstream angle on flow over a trapezoidal broad-crested weir based on numerical simulations using the open-source toolbox OpenFOAM. Eight trapezoidal broad-crested weir configurations with different upstream face angles (θ = 10°, 15°, 22.5°, 30°, 45°, 60°, 75°, 90°) were investigated under free-flow conditions. The volume-of-fluid (VOF) method and two turbulence models (the standard k-ε model and the SST k-w model) were employed in the numerical simulations. The numerical results were compared with the experimental results obtained from published papers. The root mean square error (RMSE) and the mean absolute percent error (MAPE) were used to evaluate the accuracy of the numerical results. The statistical results show that RMSE and MAPE values of the standard k-ε model are 0.35–0.67% and 0.50–1.48%, respectively; the RMSE and MAPE values of the SST k-w model are 0.25–0.66% and 0.55–1.41%, respectively. Additionally, the effects of the upstream face angle on the flow features, including the discharge coefficient and the flow separation zone, were also discussed in the present study.

Fluid Particle Motion and Lagrangian Velocities for Pulsatile Flow Through a Femoral Artery Branch Model

1987 ◽  
Vol 109 (1) ◽  
pp. 94-101 ◽  
Author(s):  
M. R. Back ◽  
Y. I. Cho ◽  
D. W. Crawford ◽  
L. H. Back
Keyword(s):  
Femoral Artery ◽  
Flow Separation ◽  
Pulsatile Flow ◽  
Reverse Flow ◽  
Branch Model ◽  
Flow Features ◽  
Flow Phase ◽  
Flow Through ◽  
Artery Flow ◽  
Artery Branch

A flow visualization study using selective dye injection and frame by frame analysis of a movie provided qualitative and quantitative data on the motion of marked fluid particles in a 60 degree artery branch model for simulation of physiological femoral artery flow. Physical flow features observed included jetting of the branch flow into the main lumen during the brief reverse flow period, flow separation along the main lumen wall during the near zero flow phase of diastole when the core flow was in the downstream direction, and inference of flow separation conditions along the wall opposite the branch later in systole at higher branch flow ratios. There were many similarities between dye particle motions in pulsatile flow and the comparative steady flow observations.

Rack Level Modeling of Air Flow Through Perforated Tile in a Data Center

2012 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Pramod Kumar ◽  
Yogendra Joshi ◽  
Thomas S. Weiss ◽  
Gary Meyer
Keyword(s):  
Data Center ◽  
Body Force ◽  
Air Flow ◽  
The Body ◽  
Physical Models ◽  
Cfd Modeling ◽  
Computational Time ◽  
Force Model ◽  
Flow Through ◽  
Tile Surface

Effective air flow distribution through perforated tiles is required to efficiently cool servers in a raised floor data center. We present detailed computational fluid dynamics (CFD) modeling of air flow through a perforated tile and its entrance to the adjacent server rack. The realistic geometrical details of the perforated tile, as well as of the rack are included in the model. Generally models for air flow through perforated tiles specify a step pressure loss across the tile surface, or porous jump model based on the tile porosity. An improvement to this includes a momentum source specification above the tile to simulate the acceleration of the air flow through the pores, or body force model. In both of these models geometrical details of tile such as pore locations and shapes are not included. More details increase the grid size as well as the computational time. However, the grid refinement can be controlled to achieve balance between the accuracy and computational time. We compared the results from CFD using geometrical resolution with the porous jump and body force model solution as well as with the measured flow field using Particle Image Velocimetry (PIV) experiments. We observe that including tile geometrical details gives better results as compared to elimination of tile geometrical details and specifying physical models across and above the tile surface. A modification to the body force model is also suggested and improved results were achieved.

scholarly journals Investigation of Flow through a Labyrinth Seal

2021 ◽  
Vol 13 (2) ◽  
pp. 51-58
Author(s):  
Marius ENACHE ◽  
Razvan CARLANESCU ◽  
Andreea MANGRA ◽  
Florin FLOREAN ◽  
Radu KUNCSER
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Labyrinth Seal ◽  
Cfd Modeling ◽  
Gas Temperature ◽  
Continuous Increase ◽  
Seal Design ◽  
Air Temperatures ◽  
Flow Through ◽  
Gas Leaks

Growing performance requirements for gas turbines have led to a continuous increase in gas temperature and pressure ratios. Together with the resulting increase in cooling flows, this requires more and more minimization and control of internal gas leaks. To meet future performance goals, the application of a new seal design and an improved understanding of leakage flow characteristics are of particular importance. The air mass flow through a labyrinth seal designed for a low-pressure turbine has been determined both through analytical calculus and CFD modeling. Different radial clearances and different air temperatures have been considered. In the next stage, the results will be validated through experiments.

scholarly journals Study on Hydraulic Performances of a 3-Bladed Inducer Based on Different Numerical and Experimental Methods

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yanxia Fu ◽  
Yujiang Fang ◽  
Jiangping Yuan ◽  
Shouqi Yuan ◽  
Giovanni Pace ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Flow Model ◽  
Static Pressure ◽  
Pressure Rise ◽  
Turbulence Models ◽  
Experimental Methods ◽  
Hydraulic Performance ◽  
Outlet Pressure ◽  
Ansys Cfx ◽  
Flow Through

The hydraulic performances of a 3-bladed inducer, designed at Alta, Pisa, Italy, are investigated both experimentally and numerically. The 3D numerical model developed in ANSYS CFX to simulate the flow through the inducer and different lengths of its inlet/outlet ducts is illustrated. The influence of the inlet/outlet boundary conditions, of the turbulence models, and of the location of inlet/outlet different pressure taps on the evaluation of the hydraulic performance of the inducer is analyzed. As expected, the predicted hydraulic performance of the inducer is significantly affected by the lengths of the inlet/outlet duct portions included in the computations, as well as by the turbulent flow model and the locations of the inlet/outlet pressure taps. It is slightly affected by the computational boundary conditions and better agreement with the test data obtained when adopting the k-ω turbulence model. From the point of the pressure tap locations, the pressure rise coefficient is much higher when the inlet/outlet static pressure taps were chosen in the same locations used in the experiments.

Development of a 2-D CFD Approach for Computing 3-D Honeycomb Labyrinth Leakage

2003 ◽  
Author(s):  
Dong-Chun Choi ◽  
David L. Rhode
Keyword(s):  
Labyrinth Seal ◽  
Algebraic Model ◽  
Operating Conditions ◽  
Cfd Model ◽  
Resource Requirement ◽  
New Approach ◽  
Computer Resource ◽  
Flow Through ◽  
D Model ◽  
Model Approach

A new approach for employing a 2-D CFD model to approximately compute a 3-D flow field such as that in a honeycomb labyrinth seal was developed. The advantage of this approach is that it greatly reduces the computer resource requirement needed to obtain a solution of the leakage for the 3-D flow through a honeycomb labyrinth. After the leakage through the stepped labyrinth seal was measured, it was used in numerically determining the value of one dimension (DTF1) of the simplified geometry 2-D approximate CFD model. Then the capability of the 2-D model approach was demonstrated by using it to compute the 3-D flow that had been measured at different operating conditions, and in some cases different distance to contact values. It was found that very close agreement with measurements was obtained in all cases, except for that of intermediate clearance and distance to contact for two sets of upstream and downstream pressure. The 2-D approach developed here offers interesting benefits relative to conventional algebraic-equation models, particularly for evaluating labyrinth geometries/operating conditions that are different from that of the data employed in developing the algebraic model.

Numerical Simulation of the Resistance and Self-Propulsion Model Tests

2018 ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Complex Structure ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Local Flow ◽  
Complex Investigation ◽  
Grid Convergence ◽  
Flow Features ◽  
Sinkage And Trim ◽  
Thrust And Torque ◽  
Resistance Coefficients

The paper proposes a series of numerical investigations performed to test and demonstrate the capabilities of a RANS solver in the area of complex ship flow simulations. Focus is on a complete numerical model for hull, propeller and rudder that can account for the mutual interaction between these components. The paper presents the results of a complex investigation of the flow computations around the hull model of the 3600 TEU MOERI containership (KCS hereafter). The resistance for the hull equipped with rudder, the POW computations as well as the self-propulsion simulation are presented. Comparisons with the experimental data provided at the Tokyo 2015 Workshop on CFD in Ship Hydrodynamics are given to validate the numerical approach in terms of the total and wave resistance coefficients, sinkage and trim, thrust and torque coefficients, propeller efficiency and local flow features. Verification and validation based on the grid convergence tests are performed for each computational case. Discussions on the efficiency of the turbulence models used in the computations as well as on the main flow features are provided aimed at clarifying the complex structure of the flow around the stern.

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