【摘要】：由于我國(guó)大量的石油和天然氣資源蘊(yùn)藏于深海,因此為了滿(mǎn)足深海資源開(kāi)采的需要,海洋立管的應(yīng)用也從淺海逐漸向深海轉(zhuǎn)移。在對(duì)立管進(jìn)行分析時(shí),不能忽視的是立管的渦激振動(dòng),立管與漩渦的流固耦合作用會(huì)導(dǎo)致立管發(fā)生響應(yīng)振動(dòng)和疲勞破壞,精確地估算立管的渦激振動(dòng)響應(yīng)和疲勞是一個(gè)重要且困難的問(wèn)題。由于立管橫向振動(dòng)的渦激振動(dòng)占百分之九十以上,本文針對(duì)深海立管簡(jiǎn)化后的梁模型和索模型,在橫向方向上,進(jìn)行了單自由度分析,主要工作為：立管的模態(tài)分析、立管激勵(lì)模態(tài)識(shí)別和激勵(lì)區(qū)域計(jì)算、立管水動(dòng)力性能分析、立管響應(yīng)分析和立管疲勞損傷預(yù)報(bào)。對(duì)立管模態(tài)進(jìn)行了分析研究。根據(jù)是否考慮立管剛度,將立管簡(jiǎn)化成兩端絞支的梁模型或者索模型,使用分離變量法推導(dǎo)了兩種模型在連續(xù)質(zhì)量密度和連續(xù)變化張力下的固有頻率和模態(tài)振型公式。為了對(duì)理論的可靠性進(jìn)行驗(yàn)證,將計(jì)算的模態(tài)分析結(jié)果與Shear7軟件的計(jì)算的模態(tài)分析結(jié)果進(jìn)行比較,二者的各階模態(tài)的固有頻率和模態(tài)振型結(jié)果幾乎一致。在考慮非連續(xù)質(zhì)量密度和非連續(xù)張力條件下,使用WKB近似分析了進(jìn)行立管模型固有頻率和模態(tài)振型計(jì)算的方法,驗(yàn)證后進(jìn)行實(shí)際計(jì)算。對(duì)立管激勵(lì)模態(tài)和激勵(lì)區(qū)域進(jìn)行了分析研究。通過(guò)比較各階固有頻率與最大、最小激勵(lì)頻率來(lái)確定立管的潛在激勵(lì)模態(tài)階數(shù),在潛在激勵(lì)模態(tài)階數(shù)內(nèi),通過(guò)渦放頻率和模態(tài)的固有頻率相等的立管位置來(lái)決定立管的能量激勵(lì)區(qū)域。立管在能量激勵(lì)區(qū)域內(nèi)受到升力的作用,在非能量激勵(lì)區(qū)域內(nèi)受到阻力的作用。通過(guò)驗(yàn)證,計(jì)算得到的參與振動(dòng)的主要激勵(lì)模態(tài)階數(shù)與Shear7計(jì)算的一致。對(duì)立管水動(dòng)力性能進(jìn)行了分析研究。本文建立了非保守升力模型和保守升力模型,通過(guò)擬合給出了不同頻率比下的升力系數(shù)與無(wú)量綱振幅比的函數(shù)關(guān)系。另外,本文根據(jù)折合速度的區(qū)別,給出了靜水中、低折合速度下和高折合速度下的阻尼模型。根據(jù)能量平衡,推導(dǎo)出了無(wú)量綱振幅比的公式,使用迭代計(jì)算立管的橫向響應(yīng)幅值。并計(jì)算了選取不同參數(shù)的立管橫向響應(yīng)幅值。對(duì)立管響應(yīng)分析和立管疲勞損傷進(jìn)行了預(yù)報(bào)。使用模態(tài)疊加法推導(dǎo)出了立管的響應(yīng)計(jì)算公式,使應(yīng)力范圍分布符合Rayleigh分布,進(jìn)行疲勞損傷預(yù)測(cè)。對(duì)不同條件的兩個(gè)立管模型進(jìn)行了響應(yīng)和疲勞分析。接著,通過(guò)改變流速、內(nèi)部流體、立管外徑、截止系數(shù)等參數(shù),對(duì)立管進(jìn)行了參數(shù)敏感性分析,并計(jì)算了立管的拖曳放大系數(shù)。
[Abstract]:Because a large amount of oil and gas resources in our country are in the deep sea, in order to meet the needs of deep sea resource exploitation, the application of marine riser is gradually transferred from shallow sea to deep sea. In the analysis of opposing tubes, the vortex-induced vibration of risers can not be ignored. The fluid-solid coupling of risers and swirls will lead to the response vibration and fatigue failure of risers. It is an important and difficult problem to accurately estimate the vortex-induced vibration response and fatigue of riser. Since the vortex-induced vibration of riser is more than 90%, the single degree of freedom analysis is carried out in the transverse direction for the simplified beam model and cable model of deep-sea riser. The main work is as follows: modal analysis of riser. The excitation mode identification and excitation region calculation, hydrodynamic performance analysis, riser response analysis and fatigue damage prediction of riser are presented. The mode of the opposite tube is analyzed and studied. According to whether the stiffness of riser is considered, the riser is simplified as a beam model or cable model with two ends of twisted support. The formulas of natural frequency and modal mode of the two models under continuous mass density and continuous varying tension are derived by using the method of separating variables. In order to verify the reliability of the theory, the calculated modal analysis results are compared with the calculated modal analysis results of Shear7 software. The results of the natural frequencies and modal modes of the two modes are almost identical. Under the condition of discontinuous mass density and discontinuous tension, the method of calculating the natural frequency and modal mode of riser model is analyzed by using WKB approximation, and the actual calculation is carried out after verification. The excitation modes and excitation regions of opposite tubes are analyzed and studied. By comparing the natural frequency of each order with the maximum and minimum excitation frequency, the potential excitation modal order of riser is determined, and within the potential excitation mode order, The energy excitation region of the riser is determined by the position of the riser with the same natural frequency of vortex discharge frequency and the natural frequency of the mode. The riser is subjected to lift in the region of energy excitation and resistance in the region of non-energy excitation. It is verified that the calculated order of the main excitation modes involved in the vibration is consistent with that of the Shear7 calculation. The hydrodynamic performance of the opposing pipe is analyzed and studied. In this paper, the non-conservative lift model and the conservative lift model are established, and the functional relationship between the lift coefficient and the dimensionless amplitude ratio under different frequency ratios is given by fitting. In addition, according to the difference of the folding velocity, the damping models of the static water, the low folding velocity and the high folding velocity are given. According to the energy balance, the formula of dimensionless amplitude ratio is derived, and the transverse response amplitude of riser is calculated iteratively. The transverse response amplitude of riser with different parameters is calculated. The response analysis and fatigue damage prediction of riser are carried out. The formula for calculating the response of riser is derived by using modal superposition method, which makes the distribution of stress range conform to Rayleigh distribution, and the fatigue damage is predicted. The response and fatigue analysis of two riser models under different conditions are carried out. Then, by changing the flow rate, internal fluid, riser diameter, cutoff coefficient and other parameters, the parameter sensitivity of the opposing tube is analyzed, and the drag magnification factor of the riser is calculated.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P756.2;TE95

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本文編號(hào)：2278401