舰船回转过程中内、外侧螺旋桨负荷变化规律的新现象

在许多教科书中,螺旋桨推进双桨船在回转过程中内、外螺旋桨负荷变化规律均有如下叙述:回转过程中内侧螺旋桨负荷远大于外侧螺旋桨负荷.这个结论也被某些实船试验结果所证实.但新近完成的某双桨船的回转试验的多个实测结果表明:外侧螺旋桨负荷远大于内侧螺旋桨负荷.在上世纪90年代国内有人已发现过这一新现象,但当时无人记录和分析以进行研究.本文报告和分析了这一新现象.文章首先简要回顾了以往教科书和某些实船试航回转过程中内、外桨负荷变化规律;然后介绍了某新船回转试验的实测结果,论述了实测结果的可信性.本文着重探讨了导致这一新现象的主要原因,如船体形状、船的运动、内外螺旋桨的运动、桨与船的相互作用和桨与桨的相互作用等.

New Phenomenon of Load Changes of Inside and Outside Propellers as Ship Turning

In many textbooks of naval architecture and marine engineering there is same statement about load changes of inside and outside propellers when ship goes around a turn that the inside propeller's load is always much heavier than the outside one. This statement was also verified by some sea trials before. In recent days, however, several recording results of a new twin-propeller ship gotten in sea trial indicated that the outside propeller's load is always heavier than the inside one. In fact last decade someone in China also noticed the phenomenon, but no one reported the phenomenon and carried out a research task of analysis of the phenomenon. In this article the new phenomenon of load changes of inside and outside propellers as ship turning is reported and explored. First it is briefly reviewed that the standard or traditional statement excerpted from the textbooks is explained, which is verified by sea trial results about load changes of twin-propeller ship when it is in a turn. Then it is reported that the latest sea trial results of the new twin-propeller ship are measured when it goes around a turn, which contradicts with what textbooks have stated ever and verified by some early sea trial results before. The creditability of recording of the sea trial results is also analyzed. Key causes which contribute to the new phenomenon are explored mainly in this article, for example, hull form, ship motion, inside and outside propellers' motion, interaction between propellers and hull, interaction between inside and outside propellers, and so on.