二冲程柴油机扭振简谐系数及相位值计算

Harmonic Coefficient of Torsional Vibration of Two-Stroke Diesel Engine

目前仍在普遍使用的英国劳氏船级社提出的简谐系数通用曲线,因考虑的因素太少,误差较大,其值普遍偏低,且无法确定相位角。劳氏曲线已不适用于近几年来所发展的新型柴油机。本文通过对二冲程柴油机切力矩简谐分析的研究,探讨了对简谐系数影响较大的因素,其中除了P、Pk、ε等参数外,结构参数λ的影响不可忽略,特别对于超长冲程柴油机,其影响更为明显。通过回归分析方法得出的简谐系数计算公式,适用于任一种二冲程机型,并能确定各次简谐切力矩的初相位角,便于激励力矩的叠加处理,对扭振特性计算具有现实意义。

The universal curves of harmonic coefficient presented by Lloyd's Register of Shipping result in great error and low value, let alone the fact that the phase angular cannot be determined, owing to less factors considered. Lloyd's curves are not suited for the new diesel engines developed over the past few years. This paper carries out a research on the harmonic analysis on tangential torque of two-stroke diesel engines, and discusses the factors which have great effect on the harmonic coefficient. In addition to the parameters pi, pk and ε, the effect of the structure parameter is not negligible, especially for super long-stroke diesel engines. The calculation formula of harmonic coefficent attained with regression analysis is suitable for any two-stroke engines; the initial phase angular of each harmonic tangential torque can be determined so that the overlapping treatment of exciting torque becomes easy.