実船プロペラ翼応力計測

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Recently Highly Skewed Propellers, HSP in short, become more popular and have been adopted on 3,000 ships in JAPAN. It can decrease the vibration of ships and greatly reduce the ship's noise. On the other hand, it has been reported that 180 serious damages have occurred on HSP. Actually, the rate of the damage on propellers was 6% which were cracked, bent and broken near the tips of the blades. FEM analysis of the blade stress is applied to the design of marine propellers effectively. But, there are no data for directly confirming whether FEM analysis predict the full scale phenomena with sufficient accuracy. It is considered that the best way to investigate the mechanism of damage on HSP and to confirm the accuracy of the FEM analysis is the measurement of the stress especially near the tip of blade on a full scale propeller. Fortunately we had an opportunity to measure the blade stress on full scale propellers of the training ship "SEIUN-MARU". At first, the conventional propeller, CP in short, and then the HSP were measured through a research project (SR206) from 1989 to 1990. FEM calculation was also carried out to confirm its accuracy by comparing the calculation results with the measured full scale data. Moreover, blade stress measurement with HSP model was conducted in the cavitation tunnel. From this research, interesting results have been obtained as described below. On CP, it was found that the tension acting toward radial direction was dominant while the stress toward tangential direction was negligibly small under ahead conditions. Due to the effect of increased blade thickness, the maximum stress in radial direction on HSP was about 70% of that on CP. It was clarified, however that much caution had to be taken about the strength in the vicinity of the trailing edge near the propeller tip where high hydrodynamic load was acted. FEM analysis simulates the stress distribution on a full scale HSP correctly if the pressure distribution on the blade is predicted with sufficient accuracy as input data. The model test in cavitation tunnel which was newly developed showed excellent agreement with the full scale measurement results. The present study will provide invaluable information on the damage mechanism of HSP, and it must be greatly useful for developing reliable program code which can calculate the pressure distribution on the propeller more accurately.
社団法人日本船舶海洋工学会の論文
1992-03-29

実船プロペラ翼応力計測

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