Question

船舶专业翻译

Tests can also be made in rotating foil facilities,in rotating disk apparatus(Dashnaw et al.,1980).or in closed-flow channel in which water is circulated(Hansson and Morch,1977).The test section can contain a specimen holder,in which a test specimen can be inserted as part of a smooth central wall.A specimen holder is shown in Fig. 6.6.6.The flow passes the wall symmetrically on both sides.Just upstream of the specimen a hole in the wall generates cavities.By appropriate adjustment of the pressure in the collapse zone and the velocity of flow the cavities collapse near the specimen surface.Our means of calibrating various cavitation damage situations is the use of a nickel alloy in a controlled material.In general,it is observed that the harder ,stronger,stiffer(large modiful)materials tend to be more resistent to erosion damage.
In order to be able to predict propeller erosion in a reliable way,the so-called “soft surface”techniques have been developed.As cavitation erosion is rapid when a critical intensity is reached,the use of soft coatings corresponding to the scaling down of intensity on the model may provide a satisfactory criterion.The surfaces used on the model propellers can vary from anodized aluminium alloy and pure soft lead through paints to engineer”s blue marking,stencil ink,and ballpoint pen ink.The time needed for the erosion may be several days for the metal surfaces and as little as 5 minutes for a complete test with stencil ink coating.The soft surface method with an appropriate test duration appears to give a reliable indiction of full-scale erosion,and the location of erosion was predicted much better than by the visual mrthod.
The ship hull is excited by the propeller mainly in two ways(1)the unsteady propeller blade loading can be transmitted to the hull through the shafting(bearing forces)and(2)the pressure field accompanying the rotating propeller blade is transmitted through the water to the hull,creating vibratory pressures at the hull plating(surface forces).Model experiments have shown that the two types of forces are of similar magnitude in noncavitating conditions.Owing to the presence of extensive nonsteady cavitation on most merchant ship propellers,the surface forces will normally be several timeshigher than the bearing forces.Thus the magnitude of the surface forces is determined to a large extent by the behavior of the cavitation present at the propeller.If these forces have to be determined by model experiments,the tests must be carried out in facilities in which the cavitating propeller can work in a wake field under as realistic conditions as possibile.The following types of facilities can be used for such tests:

Answer 1

测试也可以在旋转箔设施，在旋转圆盘器具（ Dashnaw等。 ， 1980 ） 。或在封闭的流动通道，其中水分发（汉森和Morch ， 1977年） 。试验段可以包含一个标本持有人，其中一个测试样本可以插入的一部分顺利中央wall.A标本持有者图所示。 6.6.6.The流通行证墙对称都sides.Just上游的标本中的一个漏洞产生cavities.By墙适当调整的压力在崩溃区和流速崩溃腔表面附近。我们的手段，校准各种空蚀情况下是使用镍合金在控制material.In一般，它是指出，更难，更强大，更严厉的（大modiful ）材料往往更耐腐蚀损坏。
为了能够预测螺旋桨侵蚀以可靠的方式，所谓的“软面”技术已developed.As空蚀是迅速的一个关键时强度达到，使用软涂层相应缩减强度的模式可以提供令人满意的criterion.The表面上使用的模式不同的螺旋桨可以铝合金阳极氧化和纯软导致以通过油漆工程师“蓝标记，蜡纸墨水和圆珠笔ink.The所需时间的侵蚀可能是数天的金属表面和短短的5分钟为一个完整的测试模版油墨coating.The软面法的适当的测试持续时间似乎给了可靠的indiction全面侵蚀和水土流失的位置是预计比的视觉mrthod 。
在船体很高兴的螺旋桨，主要在两个方面： （ 1 ）非定常螺旋桨叶载入中可以传播到船体通过轴系（含部队）和（ 2 ）的压力场陪同旋转螺旋桨叶片是通过水传播在船体上，创造振动压力船体电镀（表面部队） 。示范试验表明，这两种势力的类似规模的noncavitating conditions.Owing的存在广泛的非稳态空泡大部分商船螺旋桨，表面部队通常会在几个timeshigher比轴承forces.Thus的严重性，表面部队决心在很大程度上是由行为的空出席了propeller.If这些部队所定的模型试验，试验必须进行了设施，其中空泡螺旋桨可以工作在尾场下的现实条件possibile.The下列类型的设施，可用于这类试验：
记得给我加分哦。我费了好大力气。。手都快断了。 记得哦。。我8级英语。你应该很放心了吧