LNG船模运动响应数值计算与试验研究

发布时间：2018-01-02 07:43

本文关键词：LNG船模运动响应数值计算与试验研究　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着能源需求的增加和人们环保意识的增强,天然气作为一种清洁能源越来越受到青睐。对于液化天然气的海上长距离运输,LNG船无疑是最有效、最经济的选择。耐波性作为船舶安全性能的一个重要指标,船舶在波浪中的剧烈摇荡运动会影响其运营效率和安全性能,因此在船舶的设计和运营过程中是必须考虑其耐波性能。通过数值计算可以得到LNG船在波浪中的运动响应,可以在其设计过程中提供参考,而且计算得到的运动响应可以为研究液舱晃荡载荷时提供运动加载。本文采用三维时域Rankine源数值方法对LNG船有航速时在波浪中的运动响应进行了研究,主要包括以下内容:(1)Rankine源数值方法验证。应用Rankine源方法计算了Wigley II型和III型船在规则波中的运动响应,探讨了N-K(Neumann-Kelvin)线性化和D-B(Double-body)线性化这两种自由面处理方法对计算结果的影响。将计算结果与试验结果进行了对比,两者吻合较好,证明了该方法的可靠性。对于中横剖面系数较大的Wigley II船型,D-B线性化方法的计算结果与试验结果更接近。对于细长船型(比如WigleyIII型船),航速为Fr=0.2时的计算结果与试验结果吻合很好,航速为Fr=0.3、0.4时峰值区域误差在可接受的范围。总体来说,D-B线性化方法的计算结果更加准确。(2)基于Rankine源面元法对LNG船在波浪中运动响应进行了研究。文中采用线性方法和非线性方法,在时域中计算不同浪向和航速情况下LNG船在规则波中的纵摇、升沉、横摇等运动响应,并通过傅里叶变换得到运动响应传递函数曲线。航速19.5Kn的运动响应曲线与17.5Kn的响应曲线基本吻合,这说明航速对运动响应曲线影响不是很明显。浪向对运动响应比较明显,其中横浪情况下的升沉、横摇、横荡最大,迎浪时纵摇最大。在短波时非线性因素对计算结果的影响不明显,在长波时运动响应呈一定的非线性。(3)根据试验规程开展了LNG船模的耐波性试验,并应用谱分析的方法进行了实船预报。文中将试验结果与数值计算结果进行了对比,两者变化规律比较吻合,进一步证明Rankine源方法用于计算船舶运动响应的可行性。基于谱分析方法,采用JONSWAP谱对LNG船在规则波中的计算结果进行预报,得到了不同浪级情况下运动有义幅值。
[Abstract]:With the increase of energy demand and people's awareness of environmental protection, natural gas as a clean energy is more and more popular. Long distance transportation for liquefied natural gas ship at sea, LNG is undoubtedly the most effective, the most economical choice. As a ship seakeeping performance and safety of the important indicators, violent motions of ships in the the waves will influence the operation efficiency and safety performance, so in the design and operation of the ship must be considered. The seakeeping performance can be obtained through numerical calculation of response of a LNG ship in wave motion, can provide a reference in the design process, and calculate the motion response can provide motion loading for research sloshing load. This paper adopts three-dimensional time domain Rankine source numerical method for LNG ship speed of response to the movement of the wave is studied, mainly includes the following contents: (1) Rankine Verify the source numerical method. Using Rankine method to calculate the response of the source Wigley II type and III type ship in regular waves, discusses N-K (Neumann-Kelvin) and D-B (Double-body) linear linear free surface treatment method of these two kinds of effect on the calculation results. The calculation results were compared with the experimental results. A good agreement between them, proves the reliability of the method. The Wigley II hull midship section coefficient of the calculation results, the linear D-B method and experimental results closer to the slender ship. (such as the WigleyIII, speed boat) Fr= 0.2 when the calculation results agree well with the test results, the speed is Fr=0.3,0.4 the peak area of the error in the acceptable range. In general, calculation of D-B linearization method results more accurate. (2) Rankine source panel method was used to study the LNG ship motion in waves using the line based on response. Method and nonlinear method, the calculation of different waves in the time domain and speeds LNG ship in regular waves in pitch, heave response, roll, and get the motion response transfer function curve by Fourier transform. The movement speed of 19.5Kn response curve and 17.5Kn response curve is consistent, which shows that the speed of movement of the response curve of the effect is not obvious. The wave motion response is more obvious, the sea under the condition of heave, roll, yaw, yinglang when pitching. In short wave maximum nonlinear factors on the calculation result is not obvious, the movement in the long wave response is nonlinear. (3) according to the test procedures carried out seakeeping test ship model LNG, and using the method of spectrum analysis of real ship forecast results. The test results were compared with the numerical calculation, the change rule is consistent, further evidence The feasibility of the Rankine source method is applied to calculate the ship's motion response. Based on the spectral analysis method, the JONSWAP spectrum is used to predict the calculated results of the LNG ship in regular waves, and the meaningful amplitude of motion is obtained under different wave levels.

【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U661.7

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