【作者】 徐为；

【导师】 邹志利；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2006， 硕士

【摘要】 当波浪自外海传向港口时,非线性成份逐渐增强,尤其是对长周期波浪,非线性特征更为明显,对港口具有重要作用。实际港口尺寸较大,其共振波波长和周期易与入射到港口的长波波长和周期接近,可激发起港口共振波,对防波堤、港内系泊船及其它结构物产生重要影响。研究非线性波浪,尤其是非线性长波的作用具有重要的意义。 本文首先在波浪水池中进行了波浪传播的实验,旨在为检验Boussinesq方程计算模型提供依据,其次进行了非线性波浪对方箱形船体作用的实验,并依照模型位置不同分别进行了实验(一)、实验(二)和实验(三),目的一是为检验耦合的计算模型提供依据,二是分析港口波浪的非线性特征。 实验(一)和实验(二)分别研究非线性、池壁反射对波浪压力的影响。文中给出了实验(一)在不同入射波条件下无因次点压力在船体表面上的分布和压力随周期和波高的变化规律,分析了实验(一)和实验(二)中各阶压力随水平面、垂向以及波高和周期的变化。结果表明:压力幅值在波浪周期较大时,出现一阶压力减小,高阶压力增大的强非线性现象,实验中不仅出现了二阶压力大于一阶压力的情况,甚至在实验(二)中还出现了四阶压力大于三阶压力的情况。因而在港口工程和大型浮体设计中对长周期波浪应注意考虑波浪的非线性特征。 实验(三)在封闭的水池中进行,实验结果中点压力出现了次谐振荡现象,振荡周期分别是2.6s,3.0s,3.4s,对压力的影响随测点的位置而异。分别从入射波,港池的固有频率,船体和水底与间隙内流体的自振频率,波面升高四个方面分析了其可能产生的原因,结果表明:压力的次谐振荡是由水池的三维效应引起的。更多还原

【Abstract】 When waves passe on to the harbor from the open sea, non-linear ingredients strengthen gradually, in particular to longer period waves, non-linear characteristics are more obvious and have important effects on harbor. Due to relatively great sizes in actual harbor , its resonant wave periods and wavelengths are close to wave periods and wavelengths of incidents long waves, which can excite resonant wave and have important influence on breakwaters, morred ship and other structures. Consequently, studying non-linear waves, especially non-linear long waves, has the invital signifinance.In this master dissertation, firstly, the experiment of wave propagation are carried out in wave basin for the purpose of verifying Boussinesq equation computation model. In the next place, according to different locations of model, three experiments of non-linear wave actions on a box-shaped ship are respectively carried out in order to verify coupled numerical model and analysis non-linear characteristics of waves in harbour.The effects of nonlinearity and basin wall reflection on pressure are studied separately in experiment one and experiment two. In experiment one, the nondimensional point pressure distributions on the surface of the model for different wave conditions are presented , the effects of horizontal, vertical, wave periods and wave heights on the different components of pressure are analysed. The results of the two experiments show that with the increase of wave period, the first order pressure decrease and higher order pressure increase, and that the second order pressures can be greater than the first order ones. Moreover, the fourth order pressures can even be greater than the third order ones in experiment two. Therefore, the non-linear characteristics of longer period waves are important factors for port engineering design.The results of experiment three which are accomplished in a closed wave basin show that sub-harmonic surge occures on point pressures and its corresponding period is respectively 2.6s、 3.0s and 3.4s. The reason which possibly produced sub-harmonic surge are analysed separately from incident waves, natural frequency in a harbor basin, self-vibration frequency of the fluid in the gap between hull and vertical wall. The results show that sub-harmonic surge occures on point pressures are induced by three-dimensional effects of the wave basin.更多还原