• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.185-187
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• 2009

A density based method with homogeneous cavitation model to investigate cavitation-bubble collapsing behavior is proposed and applied to bubble-shock interaction problems. By applying this method, cylindrical bubbles located in the liquid and incident liquid shock wave are computed. Bubble collapsing behavior, shock-bubble interaction and shock transmission/reflection pattern are investigated.

• 한국음향학회지
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• 제38권3호
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• pp.328-333
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• 2019

본 논문은 선박 추진기의 캐비테이션 침식현상을 연구하기 위하여 추진기에서 발생하는 소음과 캐비테이션 격렬도의 연관성에 대하여 분석하였다. 캐비테이션 침식은 캐비테이션 붕괴의 빈도와 강도로 정의 할 수 있는 '캐비테이션 격렬도'와 밀접히 연관되어 있다. 캐비테이션 붕괴에 의해서 발생하는 압력파는 다양한 진폭과 지속시간의 연속적인 펄스의 형태로 나타나며 이를 캐비테이션 거동과 동조 분석하여 캐비테이션 붕괴에 따른 추진기 소음 연관성을 파악하였다. 이 기법을 경사축 추진기시험을 활용하여 추진기침식시험에 대한 정량적 평가방안을 제시하였다.

• 대한조선학회논문집
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• 제47권2호
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• pp.132-140
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• 2010

The very erosive cavitation is simulated by an inclined propeller dynamometer in the medium-size cavitation tunnel of MOERI. The inclined shaft for propeller makes strong cavitaion, which occurs around the root of a propeller blade. The cavitation begins at the leading edge of the propeller and contracted toward the trailing edge through the reentrant jet action. The cavity focused on the region near the trailing edge collapsed over the blade surface. As the impact pressure by the cavitation collapsing is too strong, it can damage the blade surface in the form of pit. This cavitation impacts created by the collapsing process are similar to the full-scale ones and are different from those by other erosion test methods. The newly developed cavitation erosion test method can be applied to evaluate the materials such as metals, ceramics and coatings in terms of cavitation resistance.

• Journal of Advanced Marine Engineering and Technology
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• 제12권1호
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• pp.53-61
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• 1988

Most of the recent for the flow field hydrofoil in partially cavitating condition are the ones which are linearized, and the problem of cavity end region for hydrofoil is not verified. This paper deals with a study on characteristics of end region flow field for partially cavitating hydrofoil by using a characteristics of shear turbulence flow and nonlinear cavity flow theory. The results obtained as follows : 1) Shear layer thickness is decreased gradually going to the end section of hydrofoil. When attack angle is large, it is appeared largely at the region of partial cavitation after its collapsing. 2) The fluctuation velocity of a second-degree relative direction have minimum value at the front of hydrofoil or at the end of hydrofoil. The difference for the validity of attack angle is appeared largely at the surrounding of .chi.$_{e}$ point. 3) The fluctuation velocity of transverse direction decrease from the maximum thickness of cavitation to the end of hydrofoil, but it undergoes largely the effect of pressure recovery. The difference is larger at the region of partial cavitation after its collapsing than at the of hydrofoil. 4) The distribution of Reynolds stress have maximum values at the region of partial cavitation after its collapsing and the end of foil, and the larger attack angle, the larger the distribution of value.e.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1282-1287
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• 2004

The bubble behavior and the radiation mechanism from a laser-induced collapsing bubble were investigated theoretically using the Keller-Miksis equation for the bubble wall motion and analytical solutions for the vapor inside bubble. The calculated time dependent bubble radius is in good agreement with observed ones. The half-width of the luminescence pulse at the collapse point, which was calculated under assumption that the light emission mechanism is black body radiation from the vapor bubble agreed well with observed value of several nanoseconds. The gas content inside the vapor bubble was too small to produce the light emission due to bremsstrahlung.

• 한국음향학회지
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• 제29권2호
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• pp.111-117
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• 2010

본 연구에서는 액체 내에서 초음파에 의해 빛이 발생하는 현상인 Sono-Luminescence (이하 SL)에 대해 연구하였다. 알칼리 금속과 알칼리 토금속 화합물을 녹인 용액에서의 SL을 관찰 하였으며, 금속 이온 농도, 금속이온의 종류를 바꾸어 가며 SL에 미치는 영향을 조사하였다. 이 때 각각의 SL에서 나오는 빛을 사진으로 찍어 RGB 성분 분석을 통해 금속 이온을 녹인 용액의 SL이 증류수에서 SL과 금속 불꽃 반응 색 또는 선스펙트럼에서 강한 세기로 방출되는 색의 합성으로 표현될 수 있는지 연구하였다. 알칼리 금속의 경우 두 색의 합성으로 잘 표현되었으나 알칼리 토금속의 경우는 그렇지 않았다. 그 이유로 SL 방출시 온도가 그리 높지 않아서 알칼리 토금속의 선스펙트럼에서 에너지가 큰 단파장의 빛이 SL에서 잘 방출되지 않기 때문인 것으로 추론하였다.