本文選題：渦激振動(dòng) + 迭代算法�。� 參考：《中國(guó)石油大學(xué)(華東)》2015年碩士論文

【摘要】：渦激振動(dòng)在工程結(jié)構(gòu)中較為常見,如海底輸油管跨的渦致振動(dòng)等,是設(shè)備疲勞破壞的誘因之一,使得對(duì)這類圓柱結(jié)構(gòu)渦激振動(dòng)的研究具有工程意義。采用數(shù)值模擬手段研究圓柱渦激振動(dòng)由于其經(jīng)濟(jì)合理的特點(diǎn)越來(lái)越多地受到研究者重視。本文針對(duì)圓柱的渦激振動(dòng)的求解問(wèn)題,為了揭示渦激振動(dòng)規(guī)律,利用FLUENT求解器對(duì)N-S方程進(jìn)行求解,提出一種迭代算法,其特點(diǎn)是利用自定義函數(shù)提取圓柱運(yùn)動(dòng)參數(shù),對(duì)圓柱運(yùn)動(dòng)方程進(jìn)行迭代求解,研究了單自由度、二自由度圓柱在均勻來(lái)流下的渦激響應(yīng),討論了不同湍流模型的影響,并利用Euler梁模型計(jì)算了工程結(jié)構(gòu)的振動(dòng)響應(yīng)。研究結(jié)果表明,本文采用的算法成功捕捉了渦激振動(dòng)的頻率鎖定、拍振等特征現(xiàn)象,可以對(duì)圓柱結(jié)構(gòu)渦激振動(dòng)做出合理計(jì)算,并得到以下結(jié)論:阻尼比、質(zhì)量比對(duì)渦激振動(dòng)響應(yīng)有顯著影響,隨著阻尼比的逐漸增加,渦激振幅、升阻力系數(shù)時(shí)程曲線將由多頻率拍振,最終演變?yōu)閱我活l率主導(dǎo)的振動(dòng),且渦激振幅逐漸減小;低質(zhì)量比圓柱產(chǎn)生的振幅更大,較高質(zhì)量比能產(chǎn)生更大的升力系數(shù),且升力相對(duì)橫向位移的相位“突跳”對(duì)應(yīng)更大的來(lái)流速度;SST k-ω模型和Realizable k-ε模型均可捕捉渦激振動(dòng)特征現(xiàn)象,SST k-ω能有效捕捉2P瀉渦模式,但計(jì)算的振幅曲線的上支振幅偏小,流體力系數(shù)的峰值及相位突跳現(xiàn)象較文獻(xiàn)值對(duì)應(yīng)的來(lái)流速度更小;Realizable k-ε模型不能重現(xiàn)2P瀉渦模式,得出的振幅曲線上支振幅偏大,但相位差的突跳現(xiàn)象比實(shí)驗(yàn)結(jié)果較文獻(xiàn)值對(duì)應(yīng)更大的來(lái)流速度;長(zhǎng)徑比對(duì)渦激振幅有顯著影響,在相同來(lái)流下,大長(zhǎng)徑比結(jié)構(gòu)產(chǎn)生的渦激振幅更大,工程應(yīng)用中應(yīng)避免設(shè)計(jì)過(guò)大長(zhǎng)徑比的單跨結(jié)構(gòu)以免激發(fā)大振幅的振動(dòng)。鑒于大阻尼、質(zhì)量對(duì)渦激振幅的有很好的抑制作用,可在符合設(shè)計(jì)要求的前提下增加石油化工設(shè)備的阻尼和質(zhì)量以降低設(shè)備的渦激振幅。本文對(duì)圓柱結(jié)構(gòu)渦激振動(dòng)的數(shù)值計(jì)算和結(jié)構(gòu)渦激振動(dòng)的抑制具有重要的理論和工程意義。
[Abstract]:Vortex-induced vibration is common in engineering structures, such as the vortex-induced vibration of submarine oil pipeline span, which is one of the inducements of equipment fatigue failure, which makes the study of vortex-induced vibration of this kind of cylindrical structure of engineering significance. More and more researchers pay more and more attention to the study of vortex induced vibration of a cylinder by numerical simulation because of its economical and reasonable characteristics. In this paper, in order to reveal the law of vortex-induced vibration, an iterative algorithm is proposed to solve the N-S equation by using fluent solver to solve the problem of vortex-induced vibration of a cylinder. The characteristic of this algorithm is to extract the motion parameters of the cylinder by using self-defined functions. The vortex-induced response of a cylinder with single degree of freedom and two degrees of freedom under uniform flow is studied. The effects of different turbulence models are discussed. The Euler beam model is used to calculate the vibration response of engineering structures. The results show that the proposed algorithm can successfully capture the characteristic phenomena such as frequency locking and beat vibration, and can be used to calculate the vortex-induced vibration of cylindrical structures. The following conclusions are obtained: damping ratio, etc. The mass ratio has a significant effect on the response of vortex-induced vibration. With the increase of damping ratio, the vortex-induced amplitude and the resistance coefficient curve will change from multi-frequency beat to single frequency-dominated vibration, and the vortex-induced amplitude will gradually decrease. The lower mass produces a larger amplitude than the cylinder, and the higher mass produces a larger lift coefficient than the cylinder. The phase "sudden jump" of lift relative to transverse displacement corresponds to a larger inflow velocity and SST k- 蠅 model and realizable k- 蔚 model can capture the characteristic phenomena of vortex-induced vibration. SST k- 蠅 can effectively capture the 2P vortex model, but the amplitude of the upper branch of the calculated amplitude curve is smaller than that of the calculated amplitude curve. The peak value of flow force coefficient and the phenomenon of phase jump are smaller than the corresponding value of the literature. The realizable k- 蔚 model can not reproduce the 2P vortex model, and the amplitude of the upper branch of the amplitude curve is larger. But the phenomenon of sudden jump of phase difference is larger than the experimental results, and the ratio of length to diameter has a significant effect on the amplitude of vortex-induced flow, and under the same flow, the amplitude of vortex-induced flow is larger than that of the structure. In engineering application, it is necessary to avoid the design of single span structure with too large aspect ratio to excite the vibration of large amplitude. In view of the large damping, mass has a good inhibition on the amplitude of vortex excitation, which can increase the damping and mass of petrochemical equipment to reduce the amplitude of vortex-induced vibration under the premise of meeting the design requirements. This paper is of great theoretical and engineering significance for the numerical calculation of vortex-induced vibration of cylindrical structures and the suppression of vortex-induced vibration.
【學(xué)位授予單位】：中國(guó)石油大學(xué)(華東)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE973.1

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