晃荡机理及荷载特性的实验研究

发布时间：2018-01-12 04:30

本文关键词：晃荡机理及荷载特性的实验研究　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：针对海洋工程和航空航天领域,晃荡问题的研究主要集中以下三个方面：模型实验研究、晃荡局部冲击以及晃荡整体荷载。本文针对以上三个问题进行了系统的综述,并分别针对自由液面的相似关系、低载液率下的局部冲击和大幅晃荡下的整体荷载开展实验研究。论文主要工作和研究结论归纳如下。(1)自由液面的相似关系研究采用弗劳德相似准则设计了三个不同比尺的GTT八边形二维液舱,分析了在20%载液率和横荡单次冲击激励下的模型实验结果。讨论了在液体冲击侧壁过程中,波高时程出现双峰现象,并对不同比尺的液舱中该双峰现象的差异进行解释；另外对不同尺寸液舱中的流场进行分析,得出模型液舱中波高的相似关系与液舱比尺有关,液舱尺寸较大时,波高幅值近似符合弗劳德相似关系,而液舱尺寸较小时,由于粘性力的影响,根据弗劳德相似还原到原型的结果偏小；最后分析了波高回落时间与弗劳德相似准则的关系。上述研究可以为模型实验的设计提供有益的参考。(2)低载液率下的晃荡局部冲击研究针对低载液率下的液体晃荡冲击机理和荷载分布规律,本文开展了载液率h/H=0.125,横荡简谐激励下的晃荡冲击实验,实验频率包含由理论推导的最低三阶固有频率。通过对波高和高速视频数据的分析,对多种典型的低载液率下的自由液面波形进行了分析；另外结合不同频率下的冲击压力分布,得出最剧烈的液体晃荡出现在一阶频率附近,其中最大波高出现在σ/σ1*=1.13附近,而最大冲击压力出现在σ/σ1*=1.2附近。而当无量纲激励频率σ/σ1*1.41以后,晃荡冲击次数急剧减少；此外对冲击压力在侧壁的空间分布进行了分析,得出在一阶固有频率附近最大冲击压力发生在自由液面附近,侧壁冲击位置随激励频率增加而升高,并且该冲击位置对激励频率敏感。(3)大幅晃荡的整体荷载研究针对飞行器燃料舱的晃荡问题开展了不同载液率,不同激励频率和不同激励幅值下模型实验研究,并结合高速视频对椭球罐液舱的晃荡物理现象进行分析。通过将实验数据与数值仿真和等效力学模型进行对比,讨论了数值仿真和等效力学模型的局限性。另外结合物理现象分析了晃荡整体力的分布规律。该工作可以为优化等效力学模型和晃荡整体力的实验设计提供参考。
[Abstract]:In the field of marine engineering and aerospace research, sloshing problems mainly focus on the following three aspects: Experimental Study on sloshing model, local impact and overall load. In this paper the sloshing on the summary of the above three problems, which were aimed at the free surface similarity relation, experimental study on the overall load of low loading rate under local liquid the impact and the large amplitude sloshing under. The main work and research conclusions of the thesis are summarized as follows. (1) research on the similar relationship of similarity criterion of designing three different scale GTT eight edge shaped two-dimensional tank using Froude free surface, analyzes the swing single impact model test results under the excitation at 20% load ratio of liquid and cross in the process are discussed. The impact of liquid in the side wall, wave high Cheng Shuangfeng phenomenon, interpretation and the phenomenon of Shuangfeng tanks of different scales in difference; in addition to the different size in a liquid tank The flow field analysis, the relationship with the tank scale similar wave model in a liquid tank, the tank size is larger, the amplitude of wave height is approximately similar to Froude, while the tank size is small, the influence of viscous force, according to the results of the prototype is similar to Froude to restore too small; the final analysis of the height of fall the time relationship with Froude. The similarity criteria provide a useful reference for the design of can model experiment. (2) the low load rate of the liquid sloshing impact on local low load rate of the liquid sloshing impact mechanism and load distribution, this paper carried out the liquid carrying rate of h/H=0.125, yaw sloshing impact experiment of a simple under excitation of the experimental frequency contains from a minimum of three order natural frequency theory. Based on the analysis of wave height and high speed video data, a variety of typical low load rate of the liquid free surface wave was In combination with different frequency analysis; the impact of pressure distribution, the most violent liquid sloshing appears near the natural frequency, the maximum wave height in sigma sigma / near 1*=1.13, while the maximum impact pressure in sigma sigma / near 1*=1.2. And when the dimensionless frequency / sigma Sigma 1*1.41, sloshing impact times sharply in addition to the impact of reduced; pressure distribution in the side wall of the space are analyzed, obtained in the vicinity of the first-order natural frequency of the maximum impact pressure occurs near the free surface and the side wall of the impact location increases with increasing the excitation frequency, and the impact of position sensitive to excitation frequency. (3) the overall load of large amplitude sloshing sloshing problems for aircraft fuel tanks are carried out under different liquid ratio, model experiment on different excitation frequencies and different excitation amplitude, combined with the physical phenomenon of high speed video sloshing tank tank of ellipsoid According to the analysis of the experimental data and numerical simulation and equivalent mechanical model are compared, the limitations of numerical simulation and equivalent mechanical model is discussed. Combining the distribution of physical phenomena of sloshing force. Provide reference for overall design of the experimental work can be optimized for the equivalent mechanical model and whole sloshing force.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U663.85

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