Interceptor hydrodynamic analysis for handling trim control problems in the high-speed crafts

2011 ◽  
Vol 225 (11) ◽  
pp. 2597-2618 ◽  
Author(s):  
H Ghassemi ◽  
M Mansouri ◽  
S Zaferanlouei
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Contact Point ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Hydrodynamic Analysis ◽  
Drag Forces ◽  
Variable Mode ◽  
Volume Method

In this study, the effects of hydrodynamic interceptors on fast crafts are investigated to find their optimum geometrical characteristics based on numerical methods. Interceptors are vertical blades installed symmetrically at the aft of the craft. They are designed either fixed or variable. In variable mode, interceptors’ heights are adjusted by various mechanisms. They also cause changes in pressure disruption around the craft and especially at the end of the hull. The pressure variations have an effect on draft height and lifting forces which directly results in a better control of trim. Using the computational fluid dynamics, the pressure distribution around the hull and its effects on trim are computed and then discussed. The Reynolds Average Navier–Stokes equations are also applied to model the flow around the fixed flat and wedge craft with an interceptor at different heights. The model is analysed based on finite volume method and SIMPLE algorithm using dynamic mesh. The results show that the interceptor causes an intense pressure rate in its contact point. It also decreases the wet surface of the craft and drag forces coefficient. At last, they lead to a better control of trim. The height of interceptor has an important effect on its efficiency and it should be selected according to the speed of the craft.

Influence of Rotor-Stator Interaction on Flow Stability in Centrifugal Pump Based on Energy Gradient Method

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Lu-Lu Zheng ◽  
Hua-Shu Dou ◽  
Wei Jiang ◽  
Xiaoping Chen ◽  
Zuchao Zhu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Energy Gradient ◽  
Rotor Stator Interaction ◽  
Volume Method

AbstractNumerical simulation is performed for the three-dimensional turbulent flow field in a centrifugal pump by solving the Reynolds-averaged Navier-Stokes equations and the RNG k-epsilon turbulent model. The finite volume method and the SIMPLE algorithm are employed for the solution of the system. All the parameters in the centrifugal pump at different blade angular positions are obtained by simulation. The flow structure is analyzed and the distributions of the energy gradient function

Thermoacoustic and buoyancy-driven transport in a square side-heated cavity filled with a near-critical fluid

1996 ◽  
Vol 316 ◽  
pp. 53-72 ◽  
Author(s):  
Bernard Zappoli ◽  
Sakir Amiroudine ◽  
Pierre Carles ◽  
Jalil Ouazzani
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Square Cavity ◽  
Piston Effect ◽  
Navier Stokes Equations ◽  
Significant Difference ◽  
Buoyancy Driven Convection ◽  
Volume Method ◽  
Very High

The mechanisms of heat and mass transport in a side-heated square cavity filled with a near-critical fluid are explored, with special emphasis on the interplay between buoyancy-driven convection and the Piston Effect. The Navier–Stokes equations for a near-critical van der Waals gas are solved numerically by means of an acoustically filtered, finite-volume method. The results have revealed some striking behaviour compared with that obtained for normally compressible gases: (i) heat equilibration is still achieved rapidly, as under zero-g conditions, by the Piston Effect before convection has time to enhance heat transport; (ii) mass equilibration is achieved on a much longer time scale by quasi-isothermal buoyant convection; (iii) due to the very high compressibility, a stagnation-point effect similar to that encountered in high-speed flows provokes an overheating of the upper wall; and (iv) a significant difference to the convective single-roll pattern generated under the same conditions in normal CO2 is found, in the form of a double-roll convective structure.

Influence of the Spacing of the Partially Porous Aerostatic Journal Bearings and the Rotating Speed on Performance of the Spindle

2017 ◽  
Vol 739 ◽  
pp. 7-11
Author(s):  
Te Yen Huang ◽  
Shi Jie Weng ◽  
Yu Kun Lin ◽  
Yu Chieh Kuo
Keyword(s):  
Stokes Equations ◽  
Simple Algorithm ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Coupling Scheme ◽  
Navier Stokes Equations ◽  
Rotating Speed ◽  
Load Carrying ◽  
Net Pressure ◽  
Volume Method

The influence of the spacing of the partially porous aerostatic journal bearings and the rotating speed of the spindle on the pressure distribution in the bearing gap and the housing gap were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, A CFD software was used to solve the Navier-Stokes equations to figure out the pressure in the bearing gap and the housing gap. The computed results indicated that when the spacing of the bearings between air outlets was increased, the pressure got higher not only in the bearing gap, but also in the housing gap. The load carrying capacity of the bearings and the stiffness of the spindle could be improved. If the spacing of bearings was reduced by adding one more bearing to the location between the original bearings, the pressure in the narrower housing gap would decrease, while that in the wider housing gap would increase. Though the extra bearing could not help increase the net pressure exerted on the spindle effectively, it did help redistribute the housing gap pressure so that the pressure difference in the air gap could be reduced and the spindle was able to rotate stably.

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure

2010 ◽  
Vol 297-301 ◽  
pp. 924-929
Author(s):  
Inès Bhouri Baouab ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Wind Flow ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Twin Buildings ◽  
Volume Method ◽  
Numerical Examination

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.

Numerical Investigation of Flow Around Bluff Bodies

1998 ◽  
Vol 14 (3) ◽  
pp. 153-159 ◽  
Author(s):  
Chou-Jiu Tsai ◽  
Ger-Jyh Chen
Keyword(s):  
Vortex Shedding ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Bluff Bodies ◽  
Near Wake ◽  
Navier Stokes Equations ◽  
Physical Description ◽  
Geometrical Shapes ◽  
Flow Phenomena ◽  
Volume Method

ABSTRACTIn this study, fluid flow around bluff bodies are studied to examine the vortex shedding phenomenon in conjuction with the geometrical shapes of these vortex shedders. These flow phenomena are numerically simulated. A finite volume method is employed to solve the incompressible two-dimensional Navier-Stokes equations. Thus, quantitative descriptions of the vortex shedding phenomenon in the near wake were made, which lead to a detailed description of the vortex shedding mechanism. Streamline contours, figures of lift coefficent, and figures of drag coefficent in various time, are presented, respectively, for a physical description.

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