深水立管涡激振动响应和疲劳损伤分析
发布时间：2018-10-18 07:20
【摘要】：由于我国大量的石油和天然气资源蕴藏于深海,因此为了满足深海资源开采的需要,海洋立管的应用也从浅海逐渐向深海转移。在对立管进行分析时,不能忽视的是立管的涡激振动,立管与漩涡的流固耦合作用会导致立管发生响应振动和疲劳破坏,精确地估算立管的涡激振动响应和疲劳是一个重要且困难的问题。由于立管横向振动的涡激振动占百分之九十以上,本文针对深海立管简化后的梁模型和索模型,在横向方向上,进行了单自由度分析,主要工作为：立管的模态分析、立管激励模态识别和激励区域计算、立管水动力性能分析、立管响应分析和立管疲劳损伤预报。对立管模态进行了分析研究。根据是否考虑立管刚度,将立管简化成两端绞支的梁模型或者索模型,使用分离变量法推导了两种模型在连续质量密度和连续变化张力下的固有频率和模态振型公式。为了对理论的可靠性进行验证,将计算的模态分析结果与Shear7软件的计算的模态分析结果进行比较,二者的各阶模态的固有频率和模态振型结果几乎一致。在考虑非连续质量密度和非连续张力条件下,使用WKB近似分析了进行立管模型固有频率和模态振型计算的方法,验证后进行实际计算。对立管激励模态和激励区域进行了分析研究。通过比较各阶固有频率与最大、最小激励频率来确定立管的潜在激励模态阶数,在潜在激励模态阶数内,通过涡放频率和模态的固有频率相等的立管位置来决定立管的能量激励区域。立管在能量激励区域内受到升力的作用,在非能量激励区域内受到阻力的作用。通过验证,计算得到的参与振动的主要激励模态阶数与Shear7计算的一致。对立管水动力性能进行了分析研究。本文建立了非保守升力模型和保守升力模型,通过拟合给出了不同频率比下的升力系数与无量纲振幅比的函数关系。另外,本文根据折合速度的区别,给出了静水中、低折合速度下和高折合速度下的阻尼模型。根据能量平衡,推导出了无量纲振幅比的公式,使用迭代计算立管的横向响应幅值。并计算了选取不同参数的立管横向响应幅值。对立管响应分析和立管疲劳损伤进行了预报。使用模态叠加法推导出了立管的响应计算公式,使应力范围分布符合Rayleigh分布,进行疲劳损伤预测。对不同条件的两个立管模型进行了响应和疲劳分析。接着,通过改变流速、内部流体、立管外径、截止系数等参数,对立管进行了参数敏感性分析,并计算了立管的拖曳放大系数。
[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.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P756.2;TE95
本文编号：2278401
[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.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P756.2;TE95
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1 饶志标;柔性立管涡激振动频域响应分析[D];上海交通大学;2010年
，本文编号：2278401
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