Applicability of Turbulence Models on Characteristics Prediction of Centrifugal Pumps

2011 ◽  
Author(s):  
Yong Wang ◽  
Houlin Liu ◽  
Shouqi Yuan ◽  
Minggao Tan ◽  
Minhua Shu
Keyword(s):  
Experimental Data ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Centrifugal Pumps ◽  
Commercial Code ◽  
Calculation Results ◽  
Sst Turbulence Model ◽  
Specific Speed ◽  
Turbulent Models ◽  
Experimental Values

In order to research the applicability of turbulence model on characteristics prediction of centrifugal pumps at the design condition, standard k-ε turbulence model, k-ω turbulence model and SST turbulence model are selected, which are commonly used in the numerical prediction for head, efficiency and NPSHr of the centrifugal pumps. By using commercial code ANSYS CFX, the all three turbulent models are used to predict the characteristics of six centrifugal pumps with the different specific speeds at the design condition, which are varied from 34.3 to 260.5. The calculation results are compared with the experimental data, and the comparison indicates that all the prediction results obtained from different turbulence models are more or less different from the experimental data. The head and efficiency predicted by SST turbulence model and k-ω turbulence model are closer and they are all bigger than that predicted by k-ε turbulence model. For low specific speed centrifugal pumps, the head and efficiency predicted by SST model and the NPSHr predicted by k-ε turbulence model are more closer to the experimental values; while for the medium and high specific speed centrifugal pumps, the head and efficiency predicted by k-ε turbulence model are better than that predicted by other models. The k-ω turbulence model and k-ε turbulence model are the best choice to predict NPSHr of medium and high specific speed centrifugal pumps respectively.

Effects of Different Turbulence Models on Three-Dimensional Unsteady Cavitating Flows in the Centrifugal Pump and Performance Prediction

2019 ◽  
Vol 20 (3-4) ◽  
pp. 487-509 ◽  
Author(s):  
Ahmed Ramadhan Al-Obaidi
Keyword(s):  
Centrifugal Pump ◽  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Experimental Results ◽  
Centrifugal Pumps ◽  
Operation Condition ◽  
Sst Model ◽  
And Performance ◽  
Turbulent Models

AbstractIn centrifugal pumps, it is important to select appropriate turbulence model for the numerical simulation in order to obtain reliable and accurate results. In this work, ten turbulence models in 3-D transient simulation for the centrifugal pump are chosen and compared. The pump performance is validated with experimental results. The numerical results reveal that the SST turbulence model was closer to the experimental results in predicting head. In addition, the pressure variation trend for the ten models is very similar which increases and then decreases from the inlet to outlet of the pump along the streamline. The SST k-ω model predicts the performance of the pump was more accurately than other turbulent models. Furthermore, the results also found that the error is the least at design operation condition 300(l/min), which is around 1.98 % for the SST model and 2.14 % and 2.38 % for the LES and transition omega model. Within 7.61 %, the errors at higher flow rate 350(l/min) for SST. The error for SST model is smaller as compared to different turbulent models. For the Realizable k-ɛ model, the errors fluctuate were more high than other models.

Calculation of Flow in Mixing Vessels With Various Turbulence Models

Volume 4 ◽  
2004 ◽  
Author(s):  
Branislav Basara ◽  
Ales Alajbegovic ◽  
Decan Beader
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Turbulence Model ◽  
Unstructured Grids ◽  
Turbulence Models ◽  
Cfd Applications ◽  
Volume Method ◽  
Rushton Impeller

The paper presents calculations of flow in a mixing vessel stirred by a six-blade Rushton impeller. Mathematical model used in computations is based on the ensemble averaged conservation equations. An efficient finite-volume method based on unstructured grids with rotating sliding parts composed of arbitrary polyhedral elements is used together with various turbulence models. Besides the standard k-ε model which served as a reference, k-ε-v2 model (Durbin, 1995) and the recently proposed hybrid EVM/RSM turbulence model (Basara & Jakirlic, 2003) were used in the calculations. The main aim of the paper is to investigate if more advanced turbulence models are needed for this type of CFD applications. The results are compared with the available experimental data.

scholarly journals Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

On the Validation of Turbulence Models for Wheel and Wheelhouse Aerodynamics

2021 ◽  
Author(s):  
Kaloki Nabutola ◽  
Sandra Boetcher
Keyword(s):  
Experimental Data ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Vehicle Body ◽  
Flow Structures ◽  
Time Resolved ◽  
Flow Control Devices ◽  
Vehicle Aerodynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift

Abstract Vehicle aerodynamics plays an important role in reducing fuel consumption. The underbody contributes to around 50% of the overall drag of a vehicle. As part of the underbody, the wheels and wheelhouses contribute to approximately 25-30% of the overall drag of a vehicle. As a result, wheel aerodynamics studies have been gaining popularity. However, a consensus of an appropriate turbulence model has not been reached, partially due to the lack of experiments appropriate for turbulence model validation studies for this type of flow. Seven turbulence models were used to simulate the flow within the wheelhouse of a simplified vehicle body, and results were shown to be incongruous with commonly used experimental data. The performance of each model was evaluated by comparing the aerodynamic coefficients obtained using computational fluid dynamics (CFD) to data collected from the Fabijanic wind tunnel experiments. The various turbulence models generally agreed with each other when determining average values, such a mean drag and lift coefficients, even if the particular values did not fall within the uncertainty of the experiment; however, they exhibited differences in the level of resolution in the flow structures within the wheelhouse. These flow structures are not able to be validated with currently available experimental data. Properly resolving flow structures is important when implementing flow control devices to reduce drag. Results from this study emphasize the need for spatially and time-resolved experiments, especially for validating LES and DES for flow within a wheelhouse.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

Comparison of Two Two-Equation Turbulence Model Used for the Numerical Simulation of Underwater Ammunition Fuze Turbine Flow Field

2012 ◽  
Vol 591-593 ◽  
pp. 1968-1972
Author(s):  
De Zhang Shen ◽  
He Zhang ◽  
Hao Jie Li
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Axial Pressure ◽  
Two Phase ◽  
Speed Increase ◽  
Pressure Coefficients ◽  
Surface Pressure Distribution ◽  
Calculation Results ◽  
Distribution Trends

To figure out the problem of turbulence simulation of underwater ammunition fuze turbine numerical simulation, respectively, realizable k-ε turbulence model and SST k-ω turbulence model are used for two-phase flow numerical simulation of the turbine rotation. The analysis compared the calculation results of the two turbulence models. The results showed that: the cavitation scale obtained from realizable k-ε turbulence model is shorter than that of SST k-ω turbulence model; turbine surface pressure distribution trends are similar of this two model, the results of realizable k-ε turbulence model are bigger than SST k-ω turbulence model; the turbine axial pressure coefficients using realizable k-ε turbulence model are also bigger than that of SST k-ω turbulence model, and the deviation increases with the speed increase.

scholarly journals Prediction of Airfoil Stall Based on a Modified k−v2¯−ω Turbulence Model

Mathematics ◽  
2022 ◽  
Vol 10 (2) ◽  
pp. 272
Author(s):  
Chenyu Wu ◽  
Haoran Li ◽  
Yufei Zhang ◽  
Haixin Chen
Keyword(s):  
Experimental Data ◽  
Shear Layer ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Naca0012 Airfoil ◽  
Separated Shear Layer ◽  
Non Equilibrium

The accuracy of an airfoil stall prediction heavily depends on the computation of the separated shear layer. Capturing the strong non-equilibrium turbulence in the shear layer is crucial for the accuracy of a stall prediction. In this paper, different Reynolds-averaged Navier–Stokes turbulence models are adopted and compared for airfoil stall prediction. The results show that the separated shear layer fixed k−v2¯−ω (abbreviated as SPF k−v2¯−ω) turbulence model captures the non-equilibrium turbulence in the separated shear layer well and gives satisfactory predictions of both thin-airfoil stall and trailing-edge stall. At small Reynolds numbers (Re~105), the relative error between the predicted CL,max of NACA64A010 by the SPF k−v2¯−ω model and the experimental data is less than 3.5%. At high Reynolds numbers (Re~106), the CL,max of NACA64A010 and NACA64A006 predicted by the SPF k−v2¯−ω model also has an error of less than 5.5% relative to the experimental data. The stall of the NACA0012 airfoil, which features trailing-edge stall, is also computed by the SPF k−v2¯−ω model. The SPF k−v2¯−ω model is also applied to a NACA0012 airfoil, which features trailing-edge stall and an error of CL relative to the experiment at CL>1.0 is smaller than 3.5%. The SPF k−v2¯−ω model shows higher accuracy than other turbulence models.

Calculation of Annular and Twin Parallel Jets Using Various Discretization Schemes and Turbulence-Model Variations

1981 ◽  
Vol 103 (2) ◽  
pp. 352-360 ◽  
Author(s):  
M. A. Leschziner ◽  
W. Rodi
Keyword(s):  
Experimental Data ◽  
Turbulence Model ◽  
Numerical Scheme ◽  
Turbulence Models ◽  
Turbulence Energy ◽  
Normal Stresses ◽  
Numerical Diffusion ◽  
Streamline Curvature ◽  
Recirculating Flow ◽  
Discretization Schemes

The paper examines the performance of three discretization schemes for convection and three turbulence-model variations when used to simulate the recirculating flow in an annular and a plane twin-parallel jet in still air. The discretization schemes considered are: (i) the hybrid central/upwind differencing scheme (CUDS), (ii) the hybrid central/skew-upwind differencing scheme (CSUDS) and (iii) the quadratic, upstream-weighted differencing scheme (QUDS). Of these, the second and third were proposed recently as superior alternatives to the first in respect of numerical diffusion. The turbulence models examined are the standard k-ε model and two variants of this. The first accounts for effects of streamline curvature on turbulence and the second for the preferential influence of normal stresses on the dissipation of turbulence energy. It is shown that numerical scheme (i) results, particularly in conjunction with the turbulence-model modifications, in severe solution errors and in a generally anomalous response to changes in the modelled viscosity field. In contrast, schemes (ii) and (iii) yield, in all cases, similar results and respond in an expected manner to the modifications. The modifications, particularly that accounting for streamline curvature, reduce, in some cases drastically, the discrepancies between computed and experimental data and yield for both jets examined generally satisfactory results.

Development of a Numerical Based Correlation for Performance Losses due to Surface Roughness in Axial Turbines

2014 ◽  
Vol 30 (6) ◽  
pp. 631-642 ◽  
Author(s):  
S. A. Moshizi ◽  
M. H. Nakhaei ◽  
M. J. Kermani ◽  
A. Madadi
Keyword(s):  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Streamline Curvature ◽  
Sst Turbulence Model ◽  
Stator Blade ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Axial Turbines

AbstractIn the present work, a recently developed in-house 2D CFD code is used to study the effect of gas turbine stator blade roughness on various performance parameters of a two-dimensional blade cascade. The 2D CFD model is based on a high resolution flux difference splitting scheme of Roe (1981). The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the zero-equation turbulence model of Baldwin-Lomax (1978) and two-equation Shear Stress Transport (SST) turbulence model. For the smooth blade, results are compared with experimental data to validate the model. Finally, a correlation between roughness Reynolds number and loss coefficient for both turbulence models is presented and tested for three other roughness heights. The results of 2D turbine blade cascades can be used for one-dimensional models such as mean line analysis or quasi-three-dimensional models e.g. streamline curvature method.

Numerical study of the flow field characteristics over a backward facing step using k-kl-ω turbulence model: comparison with different models

2018 ◽  
Vol 15 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Yasser M. Ahmed ◽  
A.H. Elbatran
Keyword(s):  
Experimental Data ◽  
Fluid Mechanics ◽  
Turbulence Model ◽  
Flow Separation ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Numerical Results ◽  
Backward Facing Step ◽  
Content Type ◽  
Case Comparison

Purpose This paper aims to investigate numerically the turbulent flow characteristics over a backward facing step. Different turbulence models with hybrid computational grid have been used to study the detached flow structure in this case. Comparison between the numerical results and the available experiment data is carried out in the present study. The results of the different turbulence models were in a good agreement with the experimental results. The numerical results also concluded that the k-kl-ω turbulence model gave favorable results compared with the experiment. Design/methodology/approach It is very important to study the flow characteristics of detached flows. Therefore, the current study investigates numerically the flow characteristics in backward facing step by using two-, three- and seven-equation turbulence models in the finite volume code ANSYS Fluent. In addition, hybrid grid has been used to improve the capability of the unstructured mesh elements for predicting the flow separation in this case. Comparison between the different turbulence models and the available experimental data was done to find the most suitable turbulence model for simulating such cases of detached flows. Findings The present numerical simulations with the different turbulence models predicted efficiently the flow characteristics over the backward facing step. The transition k-kl-ω gave the best acceptable results compared with experimental data. This is a good concluded remark in the fields of fluid mechanics and hydrodynamics because the phenomenon of flow separation is not easy to be predicted numerically and can affect greatly on the predicted drag of moving bodies in many engineering applications. Originality/value The CFD results of using different turbulence models have been validated with the experimental work, and the results of k-kl-ω proven acceptable with flow characteristics. The results of the current study conclude that the use of k-kl-ω turbulence model will contribute towards a more efficient utilization in the fields of fluid mechanics and hydrodynamics.

Sign in / Sign up

Export Citation Format

Share Document