Hybrid Navier-Stokes/Free-Wake Method for Modeling Blade-Vortex Interactions

2010 ◽  
Vol 47 (3) ◽  
pp. 975-982 ◽  
Author(s):  
Byung-Young Min ◽  
Lakshmi N. Sankar
Keyword(s):  
Navier Stokes ◽  
Vortex Interactions ◽  
Free Wake

Ship Roll Motion Damping Using Bilge Keels – A Detailed CFD Investigation

2015 ◽  
Author(s):  
Joshua Counsil ◽  
Kevin McTaggart ◽  
Dominic Groulx ◽  
Kiari Boulama
Keyword(s):  
Experimental Studies ◽  
The Body ◽  
Navier Stokes ◽  
Roll Motion ◽  
Empirical Methods ◽  
Viscous Effects ◽  
Vortex Interactions ◽  
Ship Roll ◽  
Semi Empirical ◽  
Bilge Keel

A study has been undertaken to test the value of unsteady Reynolds-averaged Navier-Stokes (URANS) and traditional semi-empirical methods in the face of complex ship roll phenomena, and provide insight into the selection of bilge keel span for varying roll amplitudes. The computational fluid dynamics (CFD) code STAR-CCM+ is employed and two-dimensional submerged bodies undergoing forced roll motion are analyzed. The spatial resolution and timestepping scheme are validated by comparison with published numerical and experimental studies. The model is then applied to a fully-submerged circular cylinder with bilge keels of varying span and undergoing roll motion at varying angular amplitudes. Extracted hydrodynamic coefficients indicate that in general, increasing displacement amplitude and bilge keel span yields increased added mass and increased damping. The relationship is complex and highly dependent upon vortex interactions with each other and the body. The semi-empirical methods used for comparison yield good predictions for simple vortex interactions but fail where viscous effects are strong. Hence, URANS methods are shown to be necessary for friction-dominated flows while semi-empirical methods remain useful for initial design considerations.

A Navier-Stokes/full potential/free wake method for rotor flows

1997 ◽  
Author(s):  
Mert Berkman ◽  
Lakshmi Sankar ◽  
Charles Berezin ◽  
Michael Torok ◽  
Mert Berkman ◽  
...  
Keyword(s):  
Navier Stokes ◽  
Full Potential ◽  
Free Wake

Navier-Stokes/Full Potential/Free-Wake Method for Rotor Flows

1997 ◽  
Vol 34 (5) ◽  
pp. 635-640 ◽  
Author(s):  
Mert E. Berkman ◽  
Lakshmi N. Sankar ◽  
Charles R. Berezin ◽  
Michael S. Torok
Keyword(s):  
Navier Stokes ◽  
Full Potential ◽  
Free Wake

Sound generation by shock–vortex interactions

1999 ◽  
Vol 380 ◽  
pp. 81-116 ◽  
Author(s):  
OSAMU INOUE ◽  
YUJI HATTORI
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Early Stage ◽  
Near Field ◽  
Time Integration ◽  
Flow Fields ◽  
Navier Stokes ◽  
Single Vortex ◽  
Vortex Interactions ◽  
Reflected Shock

Two-dimensional, unsteady, compressible flow fields produced by the interactions between a single vortex or a pair of vortices and a shock wave are simulated numerically. The Navier–Stokes equations are solved by a finite difference method. The sixth-order-accurate compact Padé scheme is used for spatial derivatives, together with the fourth-order-accurate Runge–Kutta scheme for time integration. The detailed mechanics of the flow fields at an early stage of the interactions and the basic nature of the near-field sound generated by the interactions are studied. The results for both a single vortex and a pair of vortices suggest that the generation and the nature of sounds are closely related to the generation of reflected shock waves. The flow field differs significantly when the pair of vortices moves in the same direction as the shock wave than when opposite to it.

Navier–Stokes Simulation of Transonic Blade-Vortex Interactions

1990 ◽  
Vol 112 (4) ◽  
pp. 501-509 ◽  
Author(s):  
N.-S. Liu ◽  
F. Davoudzadeh ◽  
W. R. Briley ◽  
S. J. Shamroth
Keyword(s):  
Acoustic Waves ◽  
Stokes Equations ◽  
Leading Edge ◽  
Lower Surface ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Load Variations ◽  
Vortex Interactions ◽  
Blade Vortex Interaction ◽  
Order Scheme

Transonic strong blade-vortex interaction is numerically analyzed by solving the unsteady 2-D Navier–Stokes equations using an iterative implicit second order scheme. The dominant processes during the interaction are the development of large transverse pressure gradients in the upper leading edge region and the development of disturbances at the root of the lower surface shock wave. As a result of this interaction, high pressure pulses are emitted from the leading edge, and acoustic waves are radiated from the lower surface in a region originally occupied by a supersonic pocket. In addition, severe load variations occur when the vortex is within one chord length of the blade.

scholarly journals Numerical study of flame/vortex interactions in 2-D Trapped Vortex Combustor

2014 ◽  
Vol 18 (4) ◽  
pp. 1373-1387 ◽  
Author(s):  
Prasad Mishra ◽  
Renganathan Sudharshan ◽  
Kumar Ezhil
Keyword(s):  
Numerical Study ◽  
Flame Structure ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Base Case ◽  
Primary Vortex ◽  
Vortex Interactions ◽  
Wide Range ◽  
Trapped Vortex

The interactions between flame and vortex in a 2-D Trapped Vortex Combustor are investigated by simulating the Reynolds Averaged Navier Stokes (RANS) equations, for the following five cases namely (i) non-reacting (base) case, (ii) post-vortex ignition without premixing, (iii) post-vortex ignition with premixing, (iv) pre-vortex ignition without premixing and (v) pre-vortex ignition with premixing. For the post-vortex ignition without premixing case, the reactants are mixed well in the cavity resulting in a stable ?C? shaped flame along the vortex edge. Further, there is insignificant change in the vorticity due to chemical reactions. In contrast, for the pre-vortex ignition case (no premixing); the flame gets stabilized at the interface of two counter rotating vortices resulting in reduced reaction rates. There is a noticeable change in the location and size of the primary vortex as compared to case (ii). When the mainstream air is premixed with fuel, there is a further reduction in the reaction rates and thus structure of cavity flame gets altered significantly for case (v). Pilot flame established for cases (ii) and (iii) are well shielded from main flow and hence the flame structure and reaction rates do not change appreciably. Hence, it is expected that cases (ii) and (iii) can perform well over a wide range of operating conditions.

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