• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.168-174
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• 2019

In order to investigate Propeller Open Water (POW) characteristics for the high-speed propeller in Large Cavitation Tunnel (LCT), the high-capacity inclined-shaft dynamometer was designed and manufactured. Its measuring capacities of thrust and torque are ${\pm}2200N$ and ${\pm}120N-m$, respectively. The driving motor is directly connected to the propeller shaft. Inclined angle of the propeller shaft can be adjusted up to ${\pm}10^{\circ}$. As the pressure inside LCT can be adjusted in the range of 0.1~3.0bar, we can carry out the POW test at high Reynolds number (above $1.0{\times}10^6$) without propeller cavitation and the cavitation test in uniform flow. After the new dynamometer setup in LCT, the Reynolds number variation test and propeller open-water test were conducted at the inclined angle of $0^{\circ}$ and $6^{\circ}$. The present POW results of the new dynamometer are compared with those of the existing high-capacity dynamometer in LCT and of the dynamometer in the towing-tank. Through systematic model tests and comparison with their results, the performance of the new inclined-shaft dynamometer was verified. It is thought the POW test for the high-speed propeller should be better conducted at high Reynolds number.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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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 the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.281-289
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• 2019

In order to investigate the influence of thru holes near leading edge of model propeller on cavitation behavior, a model propeller with thru holes was manufactured and tested at Large Cavitation Tunnel (LCT). The pressure distribution around the thru hole on propeller blade was numerically calculated to help understand the local flow characteristics related to cavitation behavior. The model propeller is a five bladed propeller which has 2 blades with thru holes and 3 blades with smooth surface. The cavitation observation tests were conducted at angles of $0^{\circ}$ & $6^{\circ}$ using an inclined-shaft dynamometer in LCT. There are big difference on the suction side cavitation behavior each other due to the existence of thru hole. While the blades with thou holes start generation of the sheet cavitation from the leading edge on the suction side, the blades with smooth surface generate the cloud cavitation from the mid-chord. Cavitation on the blades with thru holes shows more similar behavior to those of the full-scale propeller of which the pipe line for air injection is closed. The numerical analysis result shows that the sharp pressure drop occurs around thru holes on the blade. Consequently, the thru hole around leading edge stimulates the cavitation occurrence and stabilizes the cavitation behavior. Based on these results, the effect of thru holes on propeller cavitation behavior behind a model ship should be studied in the future.