INVESTIGATION OF CAVITATION FOR CONTRA - ROTAING PROPULSOR 'PROPELLER ON SHAFT PLUS PULLING AZIPOD'

摘要

Contra-rotating propulsor - propeller on the shaft plus electric thruster is very perspective for fast speed ship because it make possible to utilize more power from one shaft line and to increase significantly efficiency of the propulsor. The problem of cavitation is very important for propulsors of high speed ships in general, but it is even more vital for ships with CRP propulsors, where the aft propeller and the thruster operate in the slipstream of the forward propeller. At ship operation at service conditions at high speed and power together with autopilot, it is essential the CRP system performance characteristics are acceptable and do not cause any problems for the system itself, e.g. cavitation erosion on the blades or the pod unit. This problem should be taken into account at the propeller design phase. The cavitation investigation was made in the Special-propulsor Cavitation Tunnel at KSRI and it allowed studying cavitation on the subject CRP propulsor. It was found that the most dangerous effects were different forms of cavitation associated with the flow about the hub of the forward propeller. Special measures were developed to reduce the risk of the cavitation inception.