Application and comparison of different turbulence models in the three-dimensional numerical simulation of non-contact swirl sucker

2011 ◽  
Author(s):  
Qiong Wu ◽  
Qian Ye ◽  
GuoXiang Meng
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Turbulence Models

scholarly journals Numerical Simulation of the Flow Through the Return Channel of Multi-Stage Centrifugal Compressors

1998 ◽  
Author(s):  
L. J. Lenke ◽  
H. Simon
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Secondary Flows ◽  
Low Flow ◽  
Load Range ◽  
Design Point ◽  
Multi Stage ◽  
Return Channel

The numerical simulation of the flow within a return channel is reported in this paper. The investigated return channel is typically to join the exit from one stage of a centrifugal machine to the inlet of the next stage. These channel covers the range of extremely low flow coefficients. Different 3-D calculations with two different turbulence models (low-Reynolds-number k-ϵ and explicit algebraic Reynolds stress model) at the design point and part load range show the strongly three-dimensional flow structure with secondary flows on hub and shroud of the deswirl vanes. There are also significant separations downstream of the 180°-bend at suction and pressure side of the vanes. The presented numerical results are compared with experimental data in different planes and at the vane contour. The results indicate small differences between the turbulence models in the prediction of losses, flow angles and separation behavior at design point. At off-design conditions the turbulence models begin to deviate notably in their prediction of separation.

Evaluation of RANS Models in Predicting Low Reynolds, Free, Turbulent Round Jet

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Shahriar Ghahremanian ◽  
Bahram Moshfegh
Keyword(s):  
Numerical Simulation ◽  
Boundary Conditions ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Diffusion Term ◽  
Turbulent Region ◽  
Round Jet ◽  
Rans Models ◽  
Low Reynolds

In order to study the flow behavior of multiple jets, numerical prediction of the three-dimensional domain of round jets from the nozzle edge up to the turbulent region is essential. The previous numerical studies on the round jet are limited to either two-dimensional investigation with Reynolds-averaged Navier–Stokes (RANS) models or three-dimensional prediction with higher turbulence models such as large eddy simulation (LES) or direct numerical simulation (DNS). The present study tries to evaluate different RANS turbulence models in the three-dimensional simulation of the whole domain of an isothermal, low Re (Re = 2125, 3461, and 4555), free, turbulent round jet. For this evaluation the simulation results from two two-equation (low Re k-ɛ and low Re shear stress transport (SST) k-ω), a transition three-equation (k-kl-ω), and a transition four-equation (SST) eddy-viscosity turbulence models are compared with hot-wire anemometry measurements. Due to the importance of providing correct inlet boundary conditions, the inlet velocity profile, the turbulent kinetic energy (k), and its specific dissipation rate (ω) at the nozzle exit have been employed from an earlier verified numerical simulation. Two-equation RANS models with low Reynolds correction can predict the whole domain (initial, transition, and fully developed regions) of the round jet with prescribed inlet boundary conditions. The transition models could only reach to a good agreement with the measured mean axial velocities and its rms in the initial region. It worth mentioning that the round jet anomaly is still present in the turbulent region of the round jet predicted by the low Re k-ɛ. By comparing the k and the ω predicted by different turbulence models, the blending functions in the cross-diffusion term is found one of the reasons behind the more consistent prediction by the low Re SST k-ω.

Direct numerical simulation of separated flow in a three-dimensional diffuser

2010 ◽  
Vol 650 ◽  
pp. 307-318 ◽  
Author(s):  
JOHAN OHLSSON ◽  
PHILIPP SCHLATTER ◽  
PAUL F. FISCHER ◽  
DAN S. HENNINGSON
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Separated Flow ◽  
Spectral Element ◽  
Mean Flow ◽  
Development Section ◽  
Inflow Condition

A direct numerical simulation (DNS) of turbulent flow in a three-dimensional diffuser at Re = 10000 (based on bulk velocity and inflow-duct height) was performed with a massively parallel high-order spectral element method running on up to 32768 processors. Accurate inflow condition is ensured through unsteady trip forcing and a long development section. Mean flow results are in good agreement with experimental data by Cherry et al. (Intl J. Heat Fluid Flow, vol. 29, 2008, pp. 803–811), in particular the separated region starting from one corner and gradually spreading to the top expanding diffuser wall. It is found that the corner vortices induced by the secondary flow in the duct persist into the diffuser, where they give rise to a dominant low-speed streak, due to a similar mechanism as the ‘lift-up effect’ in transitional shear flows, thus governing the separation behaviour. Well-resolved simulations of complex turbulent flows are thus possible even at realistic Reynolds numbers, providing accurate and detailed information about the flow physics. The available Reynolds stress budgets provide valuable references for future development of turbulence models.

The Aerodynamic Characteristics of a Microbus

2011 ◽  
Vol 201-203 ◽  
pp. 1284-1287
Author(s):  
Xiao Ni Qi ◽  
Jian Meng ◽  
Yong Qi Liu
Keyword(s):  
Numerical Simulation ◽  
Theoretical Basis ◽  
Reliable Method ◽  
Aerodynamic Resistance ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Related Research ◽  
Flow Maps ◽  
Resistance Reduction

This work is focused on the reduction of the aerodynamic resistance of a microbus. The approach is the three dimensional (3-D) numerical simulation. The RNG k–ε turbulence models are adopted in the computation. Based on the model of SC6350 Chang’an microbus and the improved rear shape, the aerodynamic characteristics of both models at different speeds are studied. Flow maps drawn on the basis of the computed results can offer a reliable method to study the flow field around a microbus. The computed results can give a reference for study of the aerodynamic resistance reduction on a microbus for energy saving. And the results of the optimized shape can provide a theoretical basis for the related research.

scholarly journals Numerical Simulation of the DLR-F4 Wing/Body Configuration With Wall Functions

2002 ◽  
Author(s):  
Eric Goncalves ◽  
Robert Houdeville
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Transport Equation ◽  
Flow Separation ◽  
Transonic Flow ◽  
Multigrid Method ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Three Dimensional Flow ◽  
Wall Functions

This paper deals with the three-dimensional RANS computations of the transonic flow around the DLR-F4 wing-body configuration with a wall law approach. A study of the behaviour of different transport-equation turbulence models is given with comparisons to experimental data. The structure of the three-dimensional flow separation predicted by the computations is described and its topological coherence is checked. Moreover, to drastically reduce the CPU cost, a computation with a multigrid method coupled to wall functions has been tested.

Numerical Simulation of Turbulent Flows in Centrifugal Compressor Stages With Different Radial Gaps

2007 ◽  
Author(s):  
Pavel E. Smirnov ◽  
Thorsten Hansen ◽  
Florian R. Menter
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Turbulent Flows ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Detailed Comparison ◽  
Operating Point ◽  
Vaned Diffuser

Numerical simulation of three-dimensional flow in a one-stage centrifugal compressor with a diffuser of variable geometry has been performed using the ANSYS CFX 10 code. The computations were conducted using steady and unsteady flow formulations and employing the RANS two-equation turbulence models. Steady-state flow simulations in the compressor were done for two vaned diffuser geometries with different radial gaps. A detailed comparison with the experimental data reported in the literature for different operating points of the “Radiver” test case compressor is presented and discussed. Good agreement of the computed velocity field with the measurements data is obtained at the impeller exit. Downstream of the diffuser vane, prediction quality depends on the operating point. Transient simulations performed for the best operating point of the compressor did not improve considerably predictions of flow characteristics in the diffuser as compared to the steady-state approach.

Numerical Simulation and Impeller Optimization of a Centrifugal Pump

2012 ◽  
Vol 472-475 ◽  
pp. 2195-2198 ◽  
Author(s):  
Shao Ping Zhou ◽  
Pei Wen Lv ◽  
Xiao Xia Ding ◽  
Yong Sheng Su ◽  
De Quan Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Flow Field ◽  
Centrifugal Pump ◽  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Three Dimensional Flow ◽  
Field Simulation ◽  
Simulation Results

The three-dimensional flow field simulation of a centrifugal pump was presented by using commercial CFD code. In order to study the most suitable turbulence model, the three known turbulence models of Standard k-ε, RNG k-ε, Realizable k-ε were applied to simulate the flow field of the MJ125-100 centrifugal pump and predict the performance of the pump. The simulation results of head and efficiency were compared with available experimental data, and the comparison showed that the result of the numerical simulation by RNG k-ε model had the best agreement. Additionally, the effect of number of blades on the efficiency of pump was studied. The number of blades was changed from 4 to 7. The results showed that the impeller with 7 blades had the highest efficiency.

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