scholarly journals Experimental Visualization of Wave Making Phenomena around Small-Scale Ship Models in Circulating Water Channel

2008 ◽  
Vol 8 (0) ◽  
pp. 81-87
Author(s):  
Kazuo Suzuki ◽  
Shigehiro Ohkoshi ◽  
Keisuke Ohno ◽  
Motoki Hirai ◽  
Hideaki Akibayashi ◽  
...  
Keyword(s):  
Water Channel ◽  
Small Scale ◽  
Circulating Water

Spring-Arrangement Effect on Flow-Induced Vibration of a Circular Cylinder

2021 ◽  
Author(s):  
Koki Yamada ◽  
Yuga Shigeyoshi ◽  
Shuangjing Chen ◽  
Yoshiki Nishi
Keyword(s):  
Circular Cylinder ◽  
Dynamic Model ◽  
Geometric Nonlinearity ◽  
Water Channel ◽  
Fluid Flows ◽  
Flow Induced Vibration ◽  
Theoretical Evaluation ◽  
Circulating Water ◽  
Linear Dynamic ◽  
Elastically Supported

Abstract Purpose This study elucidated the effect of an inclined spring arrangement on the flow-induced vibration of a circular cylinder to understand if the effect enhances the harnessing of the energy of fluid flows. Method An experiment was conducted on a circulating water channel. A circular cylinder was partially submerged. It was elastically supported by two springs whose longitudinal directions were varied. With the speed of the water flow varied, the vibrations of the circular cylinder were measured. The measured vibrations were interpreted by la linear dynamic model. Results and discussion In a few cases, a jump in response amplitudes from zero to the maximum was observed with the spring inclination at reduced velocities of 6 to 7, whereas gradually increasing response amplitudes were observed in other cases. The inclined spring arrangement achieved greater velocity amplitudes than in cases without spring inclination. A theoretical evaluation of the measured responses indicates that the effect of the inclined springs was caused by geometric nonlinearity; the effect would be more prominent by employing a longer moment lever.

scholarly journals Hydrodynamics Around a Deep-Draft Semi-Submersible With Various Corner Shapes

2018 ◽  
Author(s):  
Yibo Liang ◽  
Longbin Tao
Keyword(s):  
Numerical Model ◽  
Experimental Test ◽  
Numerical Study ◽  
Water Channel ◽  
Hydrodynamic Characteristics ◽  
Shape Design ◽  
Circulating Water ◽  
Fluid Physics ◽  
Shape Effects ◽  
Geometric Study

A numerical study on flow over a stationary deep-draft semi-submersible (DDS) with various corner shapes was carried out to investigate the corner shape effects on the overall hydrodynamics. Three models based on a typical DDS design with different corner shapes were numerically investigated under 45° incidence. The present numerical model has been validated by an experimental test carried out in a circulating water channel. It is demonstrated that, as the corner shape design changed, the hydrodynamic characteristics alter drastically. In addition, the flow patterns were examined to reveal some insights of the fluid physics due to the changing of different corner shape designs. The detailed numerical results from the geometric study will provide a good guidance for future practical designs.

Benchmark Study and Uncertainty Assessment of Planar Motion Mechanism Tests on KVLCC2 in a Circulating Water Channel

2021 ◽  
Author(s):  
Chengqian Ma ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Uncertainty Analysis ◽  
Water Channel ◽  
Planar Motion ◽  
Acquisition Time ◽  
Motion Mechanism ◽  
Towing Tank ◽  
Circulating Water ◽  
Benchmark Study ◽  
Hydrodynamic Derivatives ◽  
Planar Motion Mechanism

Abstract The benchmark experiment research for the maneuverability of a small-scaled ship model is critical for investigating the scaled effect on the maneuvering hydrodynamic derivatives, and validating the CFD technology. Till now, there is little research on the benchmark study and uncertainty analysis for the small-scaled ship which is frequently used in the Circulating Water Channel (CWC). Therefore, an experimental study of the planar motion mechanism (PMM) tests is performed in the CWC of the SJTU. The PMM tests performed in the CWC can avoid some disadvantages of those in the towing tank, such as the limitations on the acquisition time and frequency due to the size of the towing tank, interference of the carriage on the signal acquisition. In addition, the flow field visualization for the tests in the CWC is easier to achieve compared with the experiments in the towing tank, which helps the scholars to understand the characteristic of the wake field during maneuvers. The benchmark ship is the KVLCC2 with a scaled ratio of 1/128.77. The hull forces are recorded and processed to obtain the maneuvering hydrodynamic derivatives. To assess the quality of the acquired data, randomness analysis, stationarity analysis, normality analysis, and statistical convergence are performed for the PMM tests in the CWC for the first time. Finally, the uncertainty analysis (UA) method for the PMM tests performed in the CWC is also developed.

Design and Experimental Study of Swing Arm Vortex-Induced Vibration Generating Device

2013 ◽  
Vol 365-366 ◽  
pp. 66-71
Author(s):  
Liang Ma ◽  
Peng Li ◽  
Yong Ma ◽  
Xuan Qi Ren ◽  
Hai Chao Ge ◽  
...  
Keyword(s):  
Water Flow ◽  
Water Channel ◽  
Measuring System ◽  
Vortex Induced Vibration ◽  
Low Speed ◽  
Circulating Water ◽  
System A ◽  
Swing Arm ◽  
System Vibration ◽  
Power Generation System

In order to expand the use of water flow, this paper presents a generating device using the vortex-induced vibration to gather energy from the low speed water flow. The device consists four parts: bearing frame, transmission and power generation system, vibration system and the measuring system. A prototype was made according to the design scheme, and finished the experimental test in a circulating water channel. The experiment showed that: the vibration body could get higher amplitude to drive the generator by controlling its stiffness coefficient; the unidirectional rotation transformed from the vortex-induced vibration reciprocating motion fluctuate obviously, which can be transferred into smooth rotation by the energy storage flywheel to drive the generator. The design and study of the swing arm vortex-induced vibration generating device provided a new idea for gathering energy from low-speed water flow, it would also provide a reference for the theoretical study and engineering applications of using vortex-induced vibration for generating.

scholarly journals Generating controllable velocity fluctuations using twin oscillating hydrofoils: experimental validation

2014 ◽  
Vol 750 ◽  
pp. 113-123 ◽  
Author(s):  
S. F. Harding ◽  
G. S. Payne ◽  
I. G. Bryden
Keyword(s):  
Water Channel ◽  
Theoretical Method ◽  
Companion Paper ◽  
Velocity Fluctuations ◽  
Loop Control ◽  
Circulating Water ◽  
Experimental Implementation ◽  
Closed Loop Control System ◽  
Theoretical Predictions ◽  
Loop Control System

AbstractA method for generating controllable two-dimensional velocity fluctuations using two pitching foils was derived theoretically in a previous companion paper. The present work describes the experimental implementation of the method. The experiments are carried out in a re-circulating water channel optimised to provide low turbulence intensity in the incoming flow. Velocities are measured using an acoustic Doppler velocimeter (ADV). The pitching motions of the foils are position-controlled using a closed-loop control system. Two velocity fluctuation patterns are investigated. They consist of a combination of sinusoidal components. Theoretical predictions and experimental measurements are compared in the time and frequency domain. Although some discrepancies are observed, the agreement is generally good and therefore validates the theoretical method for the conditions investigated.

scholarly journals WEATHERING EXPERIMENT ON SPILLED CRUDE OILS USING A CIRCULATING WATER CHANNEL

1995 ◽  
Vol 1995 (1) ◽  
pp. 435-422 ◽  
Author(s):  
Tsutomu Tsukihara
Keyword(s):  
Crude Oil ◽  
Water Content ◽  
Sea Water ◽  
Water Channel ◽  
Crude Oils ◽  
Oil Emulsion ◽  
Circulating Water ◽  
Water In Oil Emulsion

ABSTRACT Crude oil spilled in the sea is mixed with the sea water by the wind and waves resulting in increases in its water content and viscosity as time passes. We have constructed a small, transfer type circulating water channel of an elliptical cuit-track form. Using an attached circulating unit, together with a war tunnel, artificial waves are generated to enable simulation corresponding to the natural circumstances in the sea. The experiment disclosed the following results.Drastic changes in the properties (water content and viscosity) of the oil depend on the power of waves.Contrasting processes are observed between heavy and light crude oils during weathering.Heavy crude oils form a massive water-in-oil emulsion (mousse) with increases in both water content and viscosity.Light crude oils behave differently at summer sea temperatures,

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