Computation of unsteady three-dimensional transonic nozzle flows using k-epsilon turbulence closure

AIAA Journal ◽  
1996 ◽  
Vol 34 (7) ◽  
pp. 1331-1340 ◽  
Author(s):  
G. A. Gerolymos ◽  
I. Vallet ◽  
A. Bolcs ◽  
P. Ott
Keyword(s):  
Three Dimensional ◽  
Turbulence Closure ◽  
Nozzle Flows

Three-dimensional analysis of scramjet nozzle flows

1993 ◽  
Author(s):  
Tomiko Ishiguro ◽  
Tohru Mitani ◽  
Tetsuo Hiraiwa ◽  
Ryouji Takaki
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Nozzle Flows

Three-dimensional, two-phase supersonic nozzle flows

AIAA Journal ◽  
1983 ◽  
Vol 21 (5) ◽  
pp. 671-678 ◽  
Author(s):  
I-Shih Chang
Keyword(s):  
Supersonic Nozzle ◽  
Three Dimensional ◽  
Two Phase ◽  
Nozzle Flows

Flow in the Simplified Draft Tube of a Francis Turbine Operating at Partial Load—Part I: Simulation of the Vortex Rope

2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Hosein Foroutan ◽  
Savas Yavuzkurt
Keyword(s):  
Experimental Data ◽  
Axial Velocity ◽  
Draft Tube ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Turbulence Closure ◽  
Francis Turbine ◽  
Outer Flow ◽  
Vortex Rope ◽  
Partial Load

Numerical simulations and analysis of the vortex rope formation in a simplified draft tube of a model Francis turbine are carried out in this paper, which is the first part of a two-paper series. The emphasis of this part is on the simulation and investigation of flow using different turbulence closure models. Two part-load operating conditions with same head and different flow rates (91% and 70% of the best efficiency point (BEP) flow rate) are considered. Steady and unsteady simulations are carried out for axisymmetric and three-dimensional grid in a simplified axisymmetric geometry, and results are compared with experimental data. It is seen that steady simulations with Reynolds-averaged Navier–Stokes (RANS) models cannot resolve the vortex rope and give identical symmetric results for both the axisymmetric and three-dimensional flow geometries. These RANS simulations underpredict the axial velocity (by at least 14%) and turbulent kinetic energy (by at least 40%) near the center of the draft tube, even quite close to the design condition. Moving farther from the design point, models fail in predicting the correct levels of the axial velocity in the draft tube. Unsteady simulations are performed using unsteady RANS (URANS) and detached eddy simulation (DES) turbulence closure approaches. URANS models cannot capture the self-induced unsteadiness of the vortex rope and give steady solutions while DES model gives sufficient unsteady results. Using the proper unsteady model, i.e., DES, the overall shape of the vortex rope is correctly predicted and the calculated vortex rope frequency differs only 6% from experimental data. It is confirmed that the vortex rope is formed due to the roll-up of the shear layer at the interface between the low-velocity inner region created by the wake of the crown cone and highly swirling outer flow.

Three-dimensional, two-phase, transonic, canted nozzle flows

AIAA Journal ◽  
1990 ◽  
Vol 28 (5) ◽  
pp. 790-797 ◽  
Author(s):  
I-Shih Chang
Keyword(s):  
Three Dimensional ◽  
Two Phase ◽  
Nozzle Flows

Three-dimensional analysis of scramjet nozzle flows

1994 ◽  
Vol 10 (4) ◽  
pp. 540-545 ◽  
Author(s):  
Tomiko Ishiguro ◽  
Ryouji Takaki ◽  
Tohru Mitani ◽  
Tetsuo Hiraiwa
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Nozzle Flows

scholarly journals INFLUENCE OF TURBULENCE CLOSURE ON ESTUARINE SEDIMENT DYNAMICS AND MORPHODYNAMICS

2011 ◽  
Vol 1 (32) ◽  
pp. 78
Author(s):  
Laurent Amoudry ◽  
Alejandro Souza
Keyword(s):  
River Flow ◽  
Tidal Flow ◽  
Three Dimensional ◽  
Sediment Dynamics ◽  
Ocean Modeling ◽  
Turbulence Closure ◽  
Three Dimensional Model ◽  
Ocean Turbulence ◽  
Rectangular Basin ◽  
The Impact

Turbulence significantly impacts hydrodynamics, mixing and sediment dynamics in coastal environments. We employ a three-dimensional model, the Proudman Oceanographic Laboratory Coastal Ocean Modeling System (POLCOMS), to investigate the effects of implementing various turbulence closure schemes on sediment dynamics and morphodynamics. This model is applied to an idealized estuary, which is represented by a straight rectangular basin. A simple tidal flow is forced at one end and a constant river flow is imposed at the other. Most of the turbulence closure schemes employed are implemented via coupling to the General Ocean Turbulence Model (GOTM). Their effects are also compared to the impact of different erosion parameterizations on the numerical results and observed for different sediment properties.

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