The Design and Evaluation of Vertical Flow Circulating Water Channel for Flow Visualization Considering the Easiness and Safety of Experiment in Laboratory

2017 ◽  
Vol 2017.27 (0) ◽  
pp. 2603
Author(s):  
Ryota IWASAKI ◽  
Tomoya NAKAJIMA ◽  
Yoshiaki UEDA
Keyword(s):  
Flow Visualization ◽  
Water Channel ◽  
Vertical Flow ◽  
Circulating Water

Interference Between a Square and a Circular Cylinder

2015 ◽  
Author(s):  
Nithin S. Kumar ◽  
R. Ajith Kumar ◽  
Jayalakshmi Mohan
Keyword(s):  
Circular Cylinder ◽  
Flow Visualization ◽  
Shear Layer ◽  
Flow Pattern ◽  
Water Channel ◽  
Flow Patterns ◽  
Observation Time ◽  
Square Cylinder ◽  
Circulating Water ◽  
Layer Flow

The flow visualization studies around a square cylinder (upstream) and a circular cylinder arranged in tandem configuration is studied experimentally to identify the interference flow patterns. Flow visualization studies are carried out in a re-circulating water channel. The investigations are carried out for tandem arrangement varying the center-to-center distance (L) between the cylinders; L/B ratio is varied from 1 to 5 where B is the characteristic length. Experiments were conduct at a Reynolds number of 2100 (based on B). The results are also obtained for two tandem square cylinder configuration. The flow patterns observed are: Alternate Shear Layer Reattachment with and without gap flow, Simultanous shear layer reattachment and detached shear layer flow pattern. The time of persistence (in percentage) for each flow pattern is estimated over a sufficiently long period of observation time to identify the most influential, predominant flow pattern. Though these patterns are identical for square-square and square-circular tandem configurations, their order of predominance is different for both the configurations.

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.

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

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.

A Study of Unsteady Secondary Flow in a Water Flow Axial Turbine Model

2008 ◽  
Author(s):  
Christian Kasper ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Jochen Gier
Keyword(s):  
Flow Visualization ◽  
Vortex Breakdown ◽  
Water Channel ◽  
Leading Edge ◽  
Secondary Flows ◽  
Stagnation Region ◽  
Spiral Vortex ◽  
Passage Vortex ◽  
High Turbulence ◽  
First Time

The influence of secondary flows on the performance of turbines has been investigated in great detail in the last decades. The interaction of vortices with following blade rows has been identified to be one of the loss mechanisms within a turbo-machine. This paper presents for the first time detailed flow visualization photographs of the interaction of the vane passage vortex with the rotor. The appearance vortex breakdown could be identified before and within the rotating passage of the turbine. The measurements were taken in a vertical water channel. Water is used instead of air because the flow visualization can be realised very easily with injected ink. For different relative positions of rotor to stator a series of photographs were taken. With an image editing process the average and the pixel RMS were calculated for each relative position. The pixel RMS is a useful indicator to identify highly turbulent regions in the flow field. The photographs of the vortex breakdown show spots of high pixel RMS which are associated with very high turbulence and therefore can be regarded as sources of loss. Insight is gained into the nature of the passage vortex breakdown mechanisms as follows: first the pressure wave of the rotor stretches the vortex causing a spiral vortex instability, then the vortex interacts with the leading edge as it attempts to cut the vortex. In the stagnation region of the blade a bubble type instability forms, expands and then convects through the rotor. The absolute trajectory of the vortex fluid reveals that it exchanges no work with the rotor.

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.

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