發(fā)布時間：2018-05-17 20:53

  本文選題：二維八邊形液艙 + 比尺效應��； 參考：《大連理工大學》2015年碩士論文

【摘要】：隨著人類將油氣資源開采的目光由陸地轉向海洋,浮式液化天然氣平臺(FLNG)成了世界各國競爭的一個新型裝備制高點。但其運營過程中儲液艙內部存在嚴重的流體晃蕩沖擊問題,所以,一直都是海洋工程領域的研究熱點。目前,室內模型實驗是研究儲液艙晃蕩的重要手段。其相對于理論方法和數(shù)值方法而言,可以得到更加有效的結果來指導工程實際。但通過人們開展大量的晃蕩模型實驗研究發(fā)現(xiàn),在實驗過程中將不同比尺模型液艙得到的結果還原到原型時,會與原型實測結果之間存在不同程度的偏差,即比尺效應。鑒于此,本文通過調研國內外研究進展,系統(tǒng)總結了晃蕩比尺效應的實驗研究方法；針對海洋油氣儲運裝備中經(jīng)常采用的GTT薄膜型儲艙,構建三個不同比尺的二維八邊形液艙,并在室內開展了三個液艙之間的晃蕩沖擊比尺效應實驗研究。研究給出了詳細的分析流程,并建立了完善的室內半物理仿真實驗平臺。在實驗開始前,通過幾何相似和弗勞德相似對運動激勵、模型液艙、傳感器布置位置和實驗時間等主要影響因素均進行相似縮比。實驗所得晃蕩荷載結果還原同樣依據(jù)弗勞德相似實現(xiàn),特別是在長時間激勵作用下,實驗引入了數(shù)理統(tǒng)計方法來處理晃蕩沖擊壓力峰值,并從三個比尺液艙同一位置的壓力峰值超越概率分布研究了模型實驗與原型實驗之間的比尺效應。此次研究以20%低載液率和80%高載液率作為兩個典型的載液工況,開展了三個比尺液艙在自由液面共振頻率下,分別受到單次橫蕩沖擊激勵、長時間橫蕩和橫搖規(guī)則激勵作用下的晃蕩沖擊比尺實驗。本文通過對比分析三個比尺液艙在同一位置晃蕩沖擊壓力峰值的超越概率分布并結合相應的流場形態(tài),研究了晃蕩模型實驗與原型實驗之間的比尺效應。研究結果表明：在模型與原型液艙內同一位置都出現(xiàn)氣體截留現(xiàn)象時,將模型實驗在該位置得到的晃蕩荷載根據(jù)弗勞德相似還原到原型后,與原型實驗對應位置的結果偏差較大；當以上兩種液艙內同一位置都受到氣液混合流體沖擊時,模型實驗還原結果與原型實驗實測結果之間的偏差會有所減��；只有當二者都受到不可壓縮純液體沖擊時,由模型實驗還原后的晃蕩沖擊壓力結果才能相對真實地反映原型實驗實測結果；考慮到原型液艙晃蕩過程中許多特殊的物理現(xiàn)象在小比尺模型液艙內無法重現(xiàn),因此,應盡可能開展大比尺模型實驗來研究和評估原型液艙內的晃蕩沖擊機理。
[Abstract]:With the development of oil and gas resources from land to sea, floating liquefied natural gas platform (FLNGG) has become a new type of equipment in the world. However, there is a serious fluid sloshing impact problem in the tank, so it is always a hot topic in the field of ocean engineering. At present, indoor model experiment is an important means to study sloshing of tank. Compared with the theoretical method and numerical method, more effective results can be obtained to guide the engineering practice. However, through a large number of experiments on sloshing model, it is found that when the results obtained from different scale models are reduced to the prototype, there is a different degree of deviation between the experimental results and the measured results, that is, the scale effect. In view of this, through the research progress at home and abroad, this paper systematically summarizes the experimental research methods of sloshing scale effect, constructs three 2-D octagonal liquid tanks with different scales, aiming at the GTT thin film tank, which is often used in offshore oil and gas storage and transportation equipment. An experimental study of sloshing impact scale effect between three tanks was carried out indoors. The detailed analysis flow is given, and a perfect indoor semi-physical simulation experiment platform is established. Before the experiment, the geometric similarity and Froude similarity are used to simulate the main factors such as motion excitation, model tank, sensor position and experimental time. The reduction of the experimental results of sloshing load is also based on the Froude similarity, especially under the long-time excitation, the mathematical statistical method is introduced to deal with the peak value of the sloshing shock pressure. The scale effect between the model experiment and the prototype experiment is studied from the probability distribution of the pressure peak surpassing at the same position in the three scale tanks. In this study, 20% low load liquid rate and 80% high load liquid rate were used as two typical liquid loading conditions, and three scale tanks were subjected to a single wave shock at the resonance frequency of free liquid level, respectively. The scale experiment of sloshing impact under the action of long time rolling and rolling regular excitation. In this paper, the scale effect between the sloshing model experiment and the prototype experiment is studied by comparing and analyzing the probability distribution of the peak value of sloshing impact pressure of three scale tanks at the same position and combining with the corresponding flow pattern. The results show that when the gas interception occurs in the same position of the model and the prototype tank, the sloshing load obtained from the model experiment at this position is reduced to the prototype according to the Froude similarity. The deviation between the results of the model experiment and the prototype experiment will be reduced when the same position of the above two tanks is impacted by the gas-liquid mixed fluid and the results of the reduction of the model experiment and the measured results of the prototype experiment will be reduced. Only when both of them are impacted by incompressible pure liquid can the results of sloshing shock pressure after reduction from the model experiment reflect the measured results of the prototype experiment relatively. Considering that many special physical phenomena in the prototype tank sloshing can not be reproduced in the small scale model tank, large scale model experiments should be carried out as far as possible to study and evaluate the sloshing impact mechanism in the prototype tank.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE97

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本文編號：1902826