scholarly journals Evaluation of turbulence-model performance in jet flows

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 2402-2404
Author(s):  
S. L. Woodruff ◽  
M. Y. Hussaini ◽  
G. Erlebacher ◽  
J. M. Seiner
Keyword(s):  
Turbulence Model ◽  
Model Performance ◽  
Jet Flows

scholarly journals Evaluation of Turbulence-Model Performance in Jet Flows

AIAA Journal ◽  
2001 ◽  
Vol 39 (12) ◽  
pp. 2402-2404 ◽  
Author(s):  
S. L. Woodruff ◽  
J. M. Seiner ◽  
M. Y. Hussaini ◽  
G. Erlebacher
Keyword(s):  
Turbulence Model ◽  
Model Performance ◽  
Jet Flows

Temperature Corrected Turbulence Model for High Temperature Jet Flow

2004 ◽  
Vol 126 (5) ◽  
pp. 844-850 ◽  
Author(s):  
Khaled S. Abdol-Hamid ◽  
S. Paul Pao ◽  
Steven J. Massey ◽  
Alaa Elmiligui
Keyword(s):  
High Temperature ◽  
Turbulence Model ◽  
Room Temperature ◽  
Eddy Viscosity ◽  
Mixing Layer ◽  
Supersonic Jet ◽  
Turbulence Models ◽  
Jet Flows ◽  
Viscosity Term ◽  
Mixing Layer Flows

It is well known that the two-equation turbulence models under-predict mixing in the shear layer for high temperature jet flows. These turbulence models were developed and calibrated for room temperature, low Mach number, and plane mixing layer flows. In the present study, four existing modifications to the two-equation turbulence model are implemented in PAB3D and their effect is assessed for high temperature jet flows. In addition, a new temperature gradient correction to the eddy viscosity term is tested and calibrated. The new model was found to be in the best agreement with experimental data for subsonic and supersonic jet flows at both low and high temperatures.

Assessment of Turbulence Model Performance Adopted Near Wall Treatment for a Sharp 90° 3-D Turning Diffuser

2017 ◽  
pp. 259-273
Author(s):  
Normayati Nordin ◽  
Zainal Ambri Abdul Karim ◽  
Safiah Othman ◽  
Vijay R. Raghavan ◽  
Sharifah Adzila ◽  
...  
Keyword(s):  
Turbulence Model ◽  
Model Performance ◽  
Near Wall

Capturing S-Shape of Pump-Turbines by CFD Simulations Using an Anisotropic Turbulence Model

2019 ◽  
Author(s):  
Ernesto Casartelli ◽  
Luca Mangani ◽  
Armando Del Rio ◽  
Angelika Schmid
Keyword(s):  
Turbulence Model ◽  
Electricity Market ◽  
Vortex Formation ◽  
Model Performance ◽  
Reynolds Stress Model ◽  
Market Demand ◽  
Operational Flexibility ◽  
Transient Conditions ◽  
Sst Turbulence Model ◽  
The Right

Abstract Pump-turbines cope very well with modern electricity-market demand, having high operational flexibility and storage capabilities. Nevertheless, dynamic operation of these machines can lead to very challenging transient conditions, depending on the shape of the characteristic. Mechanical integrity can be correspondingly affected. Therefore assessment of the characteristic during the design phase, i.e. before model testing, is of crucial importance. In the past years different attempts to accurately compute the characteristic under steady (i.e. fix point) and transient conditions have been undertaken using RANS CFD. While the SST turbulence model has become the reference for machine design, it often fails for conditions close to or around instabilities. Its strength to accurately predict separation close to sound conditions (i.e. mild part- and over-load) is no more helpful. Under unstable conditions, which are characterized by continuous unsteady vortex formation, turbulence isotropy as assumed by linear two equation models is no more the right choice. Accordingly a turbulence model able to capture anisotropy, EARSM (Explicit Algebraic Reynolds Stress Model), has been implemented in an in-house code and used for the computation of the characteristic of various machines, stable and unstable, in order to assess the model performance. In this paper computations of three different machines in turbine mode are presented. Results using steady boundary conditions (BC) in the unstable region as well as transient BC like load-rejection and runaway are computed with EARSM, showing its superiority compared to linear two equation models.

Turbulence Model Upgrades for Swirling Flows

2007 ◽  
Author(s):  
J. D. Chenoweth ◽  
B. York ◽  
A. Hosangadi
Keyword(s):  
Turbulence Model ◽  
Richardson Number ◽  
Vortex Breakdown ◽  
Azimuthal Velocity ◽  
Operating Conditions ◽  
Jet Flows ◽  
Data Sets ◽  
Mixing Rate ◽  
Jet Mixing ◽  
Swirling Jet

The ability to accurately model axisymmetric, turbulent swirling jet flows over a variety of inflow conditions is evaluated. The deficiency of the standard k-ε turbulence model in predicting mixing rates in flows with streamline curvature is well known. A relatively straightforward modification to this model is made based on a local value of the flux Richardson number which accounts for the azimuthal velocity and its variation. To evaluate the effectiveness of this modification two different experimental data sets are used to compare the computational results against. All calculations were performed using the structured, density based, CRAFT CFD® code utilizing a preconditioning methodology. Both cases have initial swirl distributions that are equivalent to a solid-body rotation profile, and have swirl numbers that are low enough to remain below the vortex breakdown regime. They also have non-swirling jet data available for the same geometries and operating conditions which allows the increased jet mixing rate of swirling jets over purely axial jets to be confirmed. All calculations showed a significant improvement of centerline velocity decay as well as downstream radial velocity profiles when the Richardson number correction was activated. For the case with turbulence data, the centerline decay of turbulent kinetic energy was also much improved. An important result that was discovered was the extreme sensitivity of the downstream evolution of the jet to the specification of the initial k and ε profiles, highlighting the critical need for a comprehensive experimental characterization of all flow properties at the jet exit.

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