scholarly journals A Numerical Analysis of Gravity and Free Surface Effects on a Two-Dimensional Supercavitating Flow

2014 ◽  
Vol 51 (5) ◽  
pp. 435-449 ◽  
Author(s):  
Hyoung-Tae Kim ◽  
Hyun-Bae Lee
Keyword(s):  
Free Surface ◽  
Numerical Analysis ◽  
Surface Effects ◽  
Two Dimensional ◽  
Supercavitating Flow

Towed Underwater SPIV Measurement of Flow Fields Around a Surface-Piercing Cylinder With Free Surface Effects

2015 ◽  
Author(s):  
Jeonghwa Seo ◽  
Bumwoo Han ◽  
Shin Hyung Rhee
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Surface Wave ◽  
Flow Field ◽  
Cross Section ◽  
Surface Effects ◽  
Flow Fields ◽  
Two Dimensional ◽  
Two Dimensional Flow ◽  
Wave Induced

Effects of free surface on development of turbulent boundary layer and wake fields were investigated. By measuring flow field around a surface piercing cylinder in various advance speed conditions in a towing tank, free surface effects were identified. A towed underwater Stereoscopic Particle Image Velocimetry (SPIV) system was used to measure the flow field under free surface. The cross section of the test model was water plane shape of the Wigley hull, of which longitudinal length and width were 1.0 m and 100 mm, respectively. With sharp bow shape and slender cross section, flow separation was not expected in two-dimensional flow. Flow fields near the free-surface and in deep location that two-dimensional flow field was expected were measured and compared to identify free-surface effects. Some planes perpendicular to longitudinal direction near the model surface and behind the model were selected to track development of turbulent boundary layer. Froude numbers of the test conditions were from 0.126 to 0.40 and corresponding Reynolds numbers were from 395,000 to 1,250,000. In the lowest Froude number condition, free-surface wave was hardly observed and only free surface effects without surface wave could be identified while violent free-surface behavior due to wave-induced separation dominated the flow fields in the highest Froude number condition. From the instantaneous velocity fields, Time-mean velocity, turbulence kinetic energy, and flow structure derived by proper orthogonal decomposition (POD) were analyzed. As the free-surface effect, development of retarded wake, free-surface waves, and wave-induced separation were mainly observed.

The free surface effects on the hydrodynamics of two-dimensional hydrofoils in tandem

2020 ◽  
Vol 115 ◽  
pp. 133-141
Author(s):  
G.D. Xu ◽  
W.H. Xu ◽  
W.Y. Duan ◽  
H.P. Cai ◽  
J.T. Qi
Keyword(s):  
Free Surface ◽  
Surface Effects ◽  
Two Dimensional

Performance of a Jet-Flapped Hydrofoil Near a Free Surface

1967 ◽  
Vol 11 (04) ◽  
pp. 224-234
Author(s):  
G. R. Hough ◽  
J. P. Moran ◽  
J. C. Erickson
Keyword(s):  
Free Surface ◽  
Differential Equations ◽  
Surface Effects ◽  
Chord Length ◽  
Pitching Moment ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Jet Blowing ◽  
Submergence Depth

The problem of a two-dimensional jet-flapped hydrofoil operating near a free surface at infinite and zero Froude numbers is treated using thin-airfoil theory. The pair of coupled integro-differential equations which governs the system is derived and is reduced to a set of linear algebraic equations by assuming appropriate series forms for the vortex distributions representing the hydrofoil and the jet. A collocation procedure is then used to solve these algebraic equations. The variation of the hydrofoil lift and pitching moment with submergence depth is calculated for several jet blowing configurations. The results indicate that free-surface effects on jet-flapped hydrofoil performance appear to be significant only for operating depths of less than about one chord length for all of the configurations studied.

scholarly journals NUMERICAL ANALYSIS OF VENTILATED CAVITATION WITH FREE SURFACE EFFECTS

2013 ◽  
Vol 18 (1) ◽  
pp. 13-21
Author(s):  
M.S. Jin ◽  
H.Y. Kim ◽  
C.T. Ha ◽  
W.G. Park
Keyword(s):  
Free Surface ◽  
Numerical Analysis ◽  
Surface Effects ◽  
Ventilated Cavitation
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