Dynamic loads and thrust hysteresis of near-surface open propeller in regular head waves-an experimental study in a circulating water channel

2021 ◽  
Vol 219 ◽  
pp. 108359
Author(s):  
Wencan Zhang ◽  
Ning Ma ◽  
Xiechong Gu ◽  
Peiyuan Feng
Keyword(s):  
Experimental Study ◽  
Water Channel ◽  
Dynamic Loads ◽  
Near Surface ◽  
Circulating Water ◽  
Head Waves ◽  
Regular Head Waves

Experimental Study on Seakeeping Performance of a Catamaran with Asymmetric Demi-Hulls

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
S. Ikezoe ◽  
N. Hirata ◽  
H. Yasukawa
Keyword(s):  
Experimental Study ◽  
Ship Motion ◽  
Added Resistance ◽  
Scaled Model ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Lateral Space ◽  
Design Speed ◽  
Resistance Performance ◽  
Regular Head Waves

To capture the seakeeping performance of a catamaran with asymmetric demi-hulls, tank tests were carried out in regular head waves using a scaled model with 2.036 m in length. The lateral space between the demi-hulls was changed in the tests as W/B=2.55, 2.90 and 3.25, where W denotes breadth overall and B the breadth of the demi-hull. Also, two models with different water lines of inside flat and outside round (IF-type) and of outside flat and inside round (OF-type) were used. OF-type is superior to IF-type in both ship motion and added resistance performances in waves at the design speed. In IF-type series, the smallest clearance, W/B=2.55 is the best in the added resistance performance.

Experimental Study of the Fence Wake Manipulation Using Pulsating Jet

2009 ◽  
Author(s):  
In-Su Kang ◽  
Young-Ho Choi ◽  
Chel-Woo Park ◽  
Hyoung-Bum Kim
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Separation Bubble ◽  
Water Channel ◽  
Separated Flow ◽  
Flow Region ◽  
Velocity Fields ◽  
Circulating Water ◽  
Pulsating Jet ◽  
Upstream Flow

In this study, we experimentally investigated the effect of rear-located pulsating jet to reduce the separated flow region behind the vertical fence. The separation bubble behind the fence is the representative feature of fence wake. Control of fence wake can be used for various purposes such as the reduction of drag, increasing or decreasing the mixing, etc. The vertical fence was submerged in the turbulent boundary layer in the circulating water channel. Reynolds number based on the fence height and upstream flow velocity was 3000. The parameters used for controlling the pulsating jet included the frequency, jet speed and distance between the fence and slit nozzle. In addition, we investigated the effect of continuous jet on the fence wake. Phase averaged DPIV method was applied to measure the instantaneous velocity fields around the fence. And the obtained results were compared with those of uncontrolled fence flow. The obtained results quantitatively show the decrease of reattachment region brought by the pulsating jet. And the specific jet condition which were effective to reduce the separation bubble behind the fence were found.

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