• Journal of Advanced Marine Engineering and Technology
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• 제37권7호
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• pp.729-736
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• 2013

The turbulent properties in a mixed statistically stationary flow were investigated experimentally by a pseudo stereoscopic PIV. In order to validate the experimental results, the profiles of the turbulent kinetic energy were evaluated with the flow features. A mechanical agitator having 6 blades was installed at the bottom of the mixing tank (D=60cm, H=60cm). The agitator was rotated with 80rpm clockwise and counter-clockwise. For the measurements, three cameras were used and all were synchronized. The images captured by one of the three cameras was used for the measurement of rotational speed, and the images captured by the other two cameras were used to measure three dimensional components of velocity vectors. All vectors captured at the same rotational angle were phase averaged to construct three-dimensional vector fields to reconstruct the spatial distribution of the flow properties. It was seen that the jet scrolling along the tank was the main source of mixing.

• 대한조선학회논문집
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• 제51권4호
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• pp.311-320
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• 2014

Test uncertainty of a towed underwater Stereoscopic Particle Image Velocimetry (SPIV) system was assessed in a towing tank. To estimate the systematic error and random error of mean velocity and turbulence properties measurement, velocity field of uniform flow was measured. Total uncertainty of the axial component of mean velocity was 1.45% of the uniform flow speed and total uncertainty of turbulence properties was 3.03%. Besides, variation of particle displacement was applied to identify the change of error distribution. In results for variation of particle displacement, the error rapidly increases with particle movement under one pixel. In addition, a nominal wake of a model ship was measured and compared with existing experimental data by five-hole Pitot tubes, Pitot-static tube, and hot wire anemometer. For mean velocity, small local vortex was identified with high spatial resolution of SPIV, but has serious disagreement in local maxima of turbulence properties due to limited sampling rate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1806-1813
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• 2003

The stirred tank reactor is one of the most commonly used devices in industry for achieving mixing and reaction. Here we report on results obtained from the large eddy simulations of flow inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius. Stereoscopic PIV measurements (Hill et $al.^{(1)}$) along with the theoretical model of the impeller-induced flow (Yoon et $al.^{(2)}$) were used in defining the impeller-induced flow as superposition of circumferential, jet and tip vortex pair components. Large eddy simulation of flow in a stirred tank was carried out for the three different Reynolds numbers of 4000, 16000 and 64000. The effect of different Reynolds numbers is well observed in both instantaneous and time averaged flow fields. The instantaneous and mean vortex structures are identified by plotting an isosurfaces of swirling strength for all Reynolds numbers. The Reynolds number dependency of the nondimeansional eddy viscosity, resolve scale and subgrid scale dissipations is clearly shown in this study.