【作者】

Michael Holtmann

【摘要】

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Top bracings are widely used to control vibration resonances of engine/hull structures and to reduce the vibration of the engine frame itself in transverse and sometimes also in longitudinal direction. Therefore and because top bracings form an additional transmission path for engine excited vibrations they also may influence positively or negatively in reducing the vibration response of other machinery and equipment as well as the ship structure. Currently two types of top bracings are used: mechanical top bracings with a friction connection and hydraulic top bracings. Main advantages of the hydraulic top bracing are their improved ability to compensate relative deflections between the engine and the ship and that their dynamic characteristic can be controlled by different settings. Compared to the conventional mechanical top bracings MAN’s hydraulic top bracings have two basic settings that can be controlled by engine speed: the standard active setting and the passive setting. While in the active setting the hydraulic top bracings acts like a spring with a certain amount of stiffness, similar in its behaviour to the mechanical type, in the passive setting it acts like a damper. To get more insight about the dynamic characteristics of hydraulic top bracings and its influence on the engine and structural vibrations, MAN conducted several measurements on board different ships. Based on the measurements, the working principle and the effectiveness of the hydraulic top bracings were proven. Furthermore their stiffness and damping properties were studied. In addition to the active and passive setting also a third condition was assessed: the top bracings were drained from oil, a condition similar to no top bracings at all. Furthermore the correlation between these different top bracing settings and the vibrations response of the superstructure was investigated. In a joint project, DNV GL and MAN aimed at correlating the measurement results by the simulation findings. Based on a validated simulation model it was then even possible to investigate several more different non standard configurations and settings by additional simulations. The additional simulations covered the influence of increasing the amount of top bracings, the top bracings stiffness, but also the effect of applying top bracings in both sides of the engine structure (double sided arrangement in port and starboard side of vessel). In the paper MAN’s measurements and DNV GL’s corresponding simulations will be presented, compared and discussed.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

2

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