One of the services of MARIN is to carry out measurement campaigns on board ships and to analyse the collected data. For our navy customers MARIN is able to perform these campaigns to study several aspects of ship behaviour.

Observing cavitation for naval applications

interfere with the ship’s schedule. A high-speed camera in combination with a borescope for a 360 degrees viewing angle, results in a rapid assessment of the problems on board (figure 2).

Fig. 1 Cavitation observation through window in the hull above the propeller (GRIP project)

Propeller cavitation noise is one aspect that is often studied. The goal here is generally to determine the power and revolution rate at which cavitation inception occurs. This allows the client to identify the operational conditions required to enable the ship to stay below a certain noise level. To carry out cavitation observation for naval applications one or more windows are placed in the hull above the propeller. An example image that can be obtained from these observations is shown in figure 1. This picture was made during the GRIP (Green Retrofitting through Improved Propulsion) EU project.

Ingo Drummen

For more troubleshooting related cavitation observations, borescopes are used. For example, these are used for ships which suffer from cavitation erosion or propeller failure. MARIN’s instrumentation engineers then drill a small hole in the hull while the ship is in port or underway. In this way the activities do not

report 27

For submarines the noise signature is of crucial importance. MARIN is currently developing a cavitation observation system for full-scale submarine applications. Perfor- ming these observations in fairly dull water - without introducing artificial light – is quite a challenge, particularly when doing this fully submerged. Typical exposure values in the targeted areas were determined from existing pictures. In MARIN’s Offshore Basin the decrease in light, along with the increasing depth, was determined and a light sensitive high-speed camera was selected. This camera will be the backbone of the observation system. The system is expected to be ready for use in spring next year. With this development MARIN is again operating on the forefront of complex measurements for their Navy clients.

Fig. 2 Cavitation observation by means of high-speed camera and borescope

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28