Evaluation of Modified Two-Equation Turbulence Models for Jet Flow Predictions

2006 ◽  
Author(s):  
Nicholas Georgiadis ◽  
Dennis Yoder ◽  
William Engblom
Keyword(s):  
Turbulence Models ◽  
Jet Flow

A Numerical Study of the U-Turn Bend in Return Channel Systems for Multistage Centrifugal Compressors

2005 ◽  
Vol 219 (8) ◽  
pp. 749-756 ◽  
Author(s):  
J. M. Oh ◽  
A Engeda ◽  
M. K. Chung
Keyword(s):  
Velocity Profile ◽  
Secondary Flow ◽  
Numerical Study ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Jet Flow ◽  
Complex Flow ◽  
Centrifugal Compressors ◽  
Return Channel ◽  
Channel Systems

A qualitative numerical study of the flow in the U-turn bend of return channel systems for multistage centrifugal compressors is presented. Calculations have been carried out using the flow analysis program FLUENT. The flow in the U-turn bend is highly three-dimensional and complex. The main cause for this is the circumferential variation of the velocity profile at the inlet of the bend. The circumferential variation of the velocity profile is an unavoidable result from the wake/jet flow at the exit of the impeller. In this article, first the effect of the wake/jet flow coming into the U-turn bend is studied. It is shown that the wake/jet flow develops to form the secondary flow in the U-turn bend. The secondary flow, with the high streamline curvature of the flow in the bend, makes the flow inside the bend highly complex. This complex flow is hard to predict with conventional turbulence models that have been developed on the basis of near homogeneity of flows. Comparing the present result with a study that successfully predicted the loss and flow behaviour in the bend, a discussion is presented on the turbulence and the turbulence models. Also, the loss mechanisms in the U-turn bend are discussed in detail.

Three-dimensional numerical modeling of unconfined and confined wall-jet flow with two different turbulence models

2010 ◽  
Vol 37 (4) ◽  
pp. 576-587 ◽  
Author(s):  
Ali Khosronejad ◽  
C. D. Rennie
Keyword(s):  
Shear Stress ◽  
Finite Volume ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Jet Flow ◽  
Hydrodynamic Characteristics ◽  
Wall Jet ◽  
Bed Shear Stress ◽  
Closure Models ◽  
Wall Jet Flow

Wall-jet flow is an important flow field in hydraulic engineering, and its applications include flow from the bottom outlet of dams and sluice gates. An in-house three-dimensional (3-D) finite-volume Reynolds-averaged-Navier-Stokes (RANS) numerical model predicts the hydrodynamic characteristics of wall jets with square and rectangular source geometry. Either the low-turbulence Reynolds number k–ω or the standard k–ε turbulence closure models are applied. The calculated results for velocity profile and bed shear stress in both longitudinal and vertical directions compare favourably with both the published experimental results and the FLUENT® finite volume model. The two closure models are compared with the k–ω model, displaying 4% greater average accuracy than the k–ε model. Finally, the influence of lateral confinement of the receiving channel on wall-jet hydrodynamics is investigated, with decreased longitudinal deceleration and decreased bed shear stress observed in a confined jet. This has important implications for sediment transport in the receiving channels downstream of sluice gates.

Assessment of Turbulence Models for Heated Wall Jet Flow

2011 ◽  
Author(s):  
Ghanshyam Singh ◽  
Arvind Pattamatta ◽  
Hukam Mongia
Keyword(s):  
Turbulence Models ◽  
Jet Flow ◽  
Heated Wall ◽  
Wall Jet ◽  
Wall Jet Flow

Analysis of Unsteady Turbulent Merging Jet Flows With Temperature Difference

2002 ◽  
Author(s):  
Geun Jong Yoo ◽  
Won Dae Jeon
Keyword(s):  
Temperature Variation ◽  
Turbulent Flows ◽  
Turbulence Model ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Jet Flow ◽  
Reynolds Stress Model ◽  
Jet Flows ◽  
Test Cases ◽  
Temperature Variance

Suitable turbulence model is required in the course of establishing a proper analysis methodology for thermal stripping phenomena. For this purpose, three different turbulence models of k-ε model, modified k-ε model, and full Reynolds stress model and VLES are applied to analyze unsteady turbulent flows with temperature variation. Four test cases are selected for verification. These are vertical jet flows with water and sodium, parallel jet flow with sodium, and merging pipe flow through T-junction with sodium. The geometries of test cases well represent common places where thermal stripping might be occurred. The turbulence model computation shows overall jet flow characteristics well and good comparison of mean temperature distribution. Temperature variance (θ′2) is rather over-predicted, but location of high temperature variance is matched well with that of the large amplitude of temperature variation of experimental results. Meanwhile, mixing of hot and cold jet flow is found to be not that active.

scholarly journals Investigation of a Two-Dimensional Hot Jet’s Infrared Radiation Using Four Different Turbulence Models

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Wei Huang ◽  
Hong-hu Ji
Keyword(s):  
Temperature Field ◽  
Infrared Radiation ◽  
Turbulence Models ◽  
Jet Flow ◽  
Temperature Correction ◽  
Good Prediction ◽  
Two Dimensional ◽  
Mean Flow ◽  
Flow Mixing ◽  
Computation Error

A two-dimensional (2D) jet flow and temperature field are simulated by usingk-εT. C. model and compared with other three nontemperature corrected models, which are standardk-ε, RNGk-ε, and SSTk-ωmodel. Then based on the calculated results, the spectral infrared radiation characteristics within 4∼5 μm of the 2D jet flow were calculated. By comparing the computed results of the velocity, temperature field, and infrared radiation with the experimental measurements, it shows that thek-εT. C. model predicts mean flow mixing more rapidly and the turbulent kinetic energy dissipates earlier than with no temperature correction; thek-εT. C. model could give a good prediction for the velocity and temperature distributions on the centerline of the 2D hot gas jet, but not on the locations off the centerline. The maximum computation error of the 2D hot jet infrared radiation is decreased from 86% to 26%, and the accuracy of the computation is greatly improved.

Evaluation of Modified Two-Equation Turbulence Models for Jet Flow Predictions

AIAA Journal ◽  
2006 ◽  
Vol 44 (12) ◽  
pp. 3107-3114 ◽  
Author(s):  
Nicholas J. Georgiadis ◽  
Dennis A. Yoder ◽  
William A. Engblom
Keyword(s):  
Turbulence Models ◽  
Jet Flow
Sign in / Sign up

Export Citation Format

Share Document