Measurement and Analysis of Surface Force and Cavitation of Actual Ship Equipped with CPP

利用日本商船神户大学实船“Fukae-Marul”实船，排水量762吨，垂线间距45m，以及直径2.1m.1的四叶偏转可调螺距螺旋桨，对螺旋桨正上方的压力脉动和螺旋桨空化现象进行了测量和分析。在Kii海峡的夜间和清水区进行了试验航行，成功地记录了空泡现象。2还成功地获得了不同螺旋桨转速和桨叶角条件下的压力脉动数据。到目前为止，关于配备CPP的实际船只的数据很少。因此，这里得到的数据可以被认为是非常有价值的。3.压力波动很大…在幅值和频率上更多地受到空化的影响。在频率方面，当不发生空化时，主分量等于叶片频率，而当发生空化并发光时，叶片频率的第二和第三阶成为主要分量。4由于是转速和叶片角度的两个变量，CPPship对空化特性的影响不像FPP-ship那么简单。分析发现，叶片攻角可能是一个可能的变量，能够统一上述两个变量的影响。5到目前为止，已经有几种方法来估算考虑空泡效应的螺旋桨表面力。其中三人检查了自己的有效性。结果表明，这些常规方法对FPP船来说是有效的，但也是有限的。然而，对于CPP和/或斜桨，这些方法并不都是有效的，开发新的估计方法不仅适用于FPP，而且适用于CPP和斜桨，将是未来的任务。较少

Measurements and Analysis were carried out regarding pressure fluctuation on hull surface just above a propeller and propeller cavitation phenomena by the use of a actual ship "Fukae-marul", which is a training ship of Kobe University of Mercantile Marine, and has the displacement 762tonnes, the length between perpendiculars 45m, and a 4-bladed skewed and controllable pitch propeller with diameter 2.1m.1 A stroboscope synchronized with propeller revolution and a video camera were mounted on the outside hull near propeller. Experimental voyages were carried out in nighttime and in clear water area of the Kii Channel, and succeeded in recording cavitation phenomena.2 The data of pressure fluctuation were also successfully obtained at various conditions of propeller revolution and blade angle. There have been reported so far a very little data regarding actual ship equipped with a CPP. The data obtained here, therefore, can be considered to be-very valuable.3 Pressure fluctuation is great … More ly influenced by cavitation in both of amplitude and frequency. As for frequency, main component is equal to blade frequency when cavitation does not occur, while the 2nd and 3rd modes of blade frequncy become dominant components as cavitation occurs and glows.4 Because of being two variables of revolution and blade angle, the influence of CPPship on cavitation characteristics is not so simple as that of FPP-ship. The analysis could have found that blade attack angle could be a possible variable to be able to unify the influences of both variables mentioned above.5 There have been so far several methods which estimate the propeller surface force taking into consideration of cavitation effects. Three of them examined about their validities. It was revealed that these conventional methods are valid, though ia a limited extent, for FPP-ship. For CPP and/or skewed propeller, however, all of them are not valid.It would be a future task to develop new estimation method being adaptable not only for FPP but also for CPP and skewed propeller. Less