某船推进系统非线性动力.doc
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某船推进系统非线性动力,摘要以往对船舶推进系统的研究中，通常以轴系本身为主，主机与轴系作为单独对象进行分析，并未考虑主机、轴系、螺旋桨之间的相互作用与影响。本文以某船推进系统为研究对象，应用有限元和子结构缩减法，建立曲轴、轴系、螺旋桨以及各简易轴承座等体单元，通过非线性联接单元将各体单元连接，建立推进系统非线性多体动力学模型。在考虑主机额定工...
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摘 要
以往对船舶推进系统的研究中，通常以轴系本身为主，主机与轴系作为单独对象进行分析，并未考虑主机、轴系、螺旋桨之间的相互作用与影响。本文以某船推进系统为研究对象，应用有限元和子结构缩减法，建立曲轴、轴系、螺旋桨以及各简易轴承座等体单元，通过非线性联接单元将各体单元连接，建立推进系统非线性多体动力学模型。在考虑主机额定工况燃气压力和螺旋桨激振力等条件下进行了计算，分析了曲轴、轴系、螺旋桨的受力与位移，以及螺旋桨载荷的影响，其中，轴系部分重点分析了艉轴后轴承处轴系的受力与位移情况。结果表明：
1）与未考虑螺旋桨载荷时相比，受螺旋桨载荷影响，曲轴输出端轴向位移波动加剧，相对角位移最大值增加了66%；2）两种情况下曲轴各轴颈竖直水平方向受力与位移的幅值与变化趋势基本一致，但螺旋桨载荷引起了其工作循环内的微小跳动，输出端尤为明显。因此，在进行曲轴轴承润滑特性分析时，应该考虑螺旋桨外部载荷的影响，使得模型更符合实际情况。
3）受螺旋桨载荷的影响，艉轴后轴承位置轴系受力与位移随曲柄转角呈周期性变化，受力主要集中在两端，靠近螺旋桨一端约是另一端的5倍，且竖直方向明显大于水平方向。4）螺旋桨竖直方向位移基本为负，水平方向正负交替且幅值相当，螺旋桨惯性力矩对轴系扭矩产生显著影响，其幅值与激振扭矩幅值相当。5）计算得螺旋桨相对角位移最大值为0.087rad；竖直向下位移最大值为2.86mm；轴向位移最大值为1.18mm，向主机方向偏移。为提高船舶推进系统可靠性及其优化设计提供了重要参考。
关键词：船舶推进系统，柴油机，激振力，动力学
ABSTRACT
In the dynamic investigation of propulsion shaft system formerly, main engine and shaft is analyzed separately. As a result the interaction of main engine, shaft and propeller could not be considered. In this thesis the propulsion shaft system is investigated. A multi-body dynamic model of propulsion shaft system including diesel engine, shaft, propeller and simple bearing block is established based on FE-Models and substructure technique, where different bodies are coupled by several non-linear coupling elements. The calculation is performed when combustion pressure and propeller exciting force is loaded on corresponding bodies at the state of power rating. The dynamic behavior of crankshaft, shaft and propeller is investigated within a complete engine cycle, as well as the influence of propeller exciting force to the system.
The results indicate that, as the affects of propeller exciting force, at drive end of crankshaft, the oscillation of axial displacement is intensified obviously, the relative angular displacement is increased 66%. Under different conditions, the trend and the maximum value of force and displacement of journals are consistent, but that is fluctuating tiny. So it is better to consider exterior load when analyzing the lubrication of crankshaft, for the model being more realizable. The force and displacement of shaft is analyzed, and that of propeller and shaft at rear stern bearing location is mainly analyzed. At rear stern bearing location, as influence of propeller load, the force and displacement is changed periodically along with the periodicity of exciting moment, and the value in vertical direction is bigger. The value of force at two ends is much bigger than that in middle, and the force close to propeller is about 5 times of that at the other end. The gravity and inertial moment of propeller affects dynamics obviously, the maximum value of inertial moment is almost equal to that of exciting torque, as a result the displacement in vertical direction is minus most time within an engine cycle, in horizontal direction the value alternate between plus and minus. For propeller, the maximum value of displacement in vertical direction is 2.86mm, and 1.18mm in axial direction to the engine, the maximum relative angular displacement value is 0.087radian. That provides an important reference for analyzing and improving the reliability of propulsion system and implementing its optimization.
Key words: propulsion shaft system, marine diesel, exciting force, dynamic
目 录
摘 要 I
ABSTRACT III
第一章 绪论 1
1.1 研究背景及意义 1
1.2 国内外研究现状 1
1.2.1动力学研究方面 2
1.2.2动力学建模方面 2
1.3 研究内容与方法 3
第二章 船舶推进系统模型 5
2.1 理论基础 5
2.1.1 有限元法 5
2.1.2 多体动力学基本理论 5
2.2 船舶推进系统有限元模型 7
2.2.1 曲轴 7
2.2.2 轴系 9
2.2.3 螺旋桨 11
2.2.4 轴承座 11
2.3 船舶推进系统多体动力学模型 13
2.3.1 推进系统组成及基本参数 14
2.3.2 定义体单元 16
2.3.3 定义非线性联接单元 17
2.3.4 推进系统多体动力学模型 22
2.4 本章小结 23
第三章 计算外部激振力 25
3.1 气缸燃气压力 25
3.2 计算螺旋桨激振力 26
3.2.1 螺旋桨扭转激振力 27
3.2.2 螺旋桨轴向激振力 28
3.2.3 螺旋桨弯曲激振力 29
3.3 本章小结 30
第四章 柴油主机动力学分析 31
4.1 曲轴全局运动分析 31
4.2 曲轴系动力学分析 34
4.2.1 活塞受力分析 34
4.2.2 曲轴受力分析 34
4.2.3 曲轴输出端分析 36
4.2.4 轴心轨迹分析 38
4.3 本章小结 41
第五章 推进轴系动力学分析 43
5.1 轴系分析 43
5.2 螺旋桨 46
5.3 本章小结 48
第六章 结论与展望 49-br..
以往对船舶推进系统的研究中，通常以轴系本身为主，主机与轴系作为单独对象进行分析，并未考虑主机、轴系、螺旋桨之间的相互作用与影响。本文以某船推进系统为研究对象，应用有限元和子结构缩减法，建立曲轴、轴系、螺旋桨以及各简易轴承座等体单元，通过非线性联接单元将各体单元连接，建立推进系统非线性多体动力学模型。在考虑主机额定工况燃气压力和螺旋桨激振力等条件下进行了计算，分析了曲轴、轴系、螺旋桨的受力与位移，以及螺旋桨载荷的影响，其中，轴系部分重点分析了艉轴后轴承处轴系的受力与位移情况。结果表明：
1）与未考虑螺旋桨载荷时相比，受螺旋桨载荷影响，曲轴输出端轴向位移波动加剧，相对角位移最大值增加了66%；2）两种情况下曲轴各轴颈竖直水平方向受力与位移的幅值与变化趋势基本一致，但螺旋桨载荷引起了其工作循环内的微小跳动，输出端尤为明显。因此，在进行曲轴轴承润滑特性分析时，应该考虑螺旋桨外部载荷的影响，使得模型更符合实际情况。
3）受螺旋桨载荷的影响，艉轴后轴承位置轴系受力与位移随曲柄转角呈周期性变化，受力主要集中在两端，靠近螺旋桨一端约是另一端的5倍，且竖直方向明显大于水平方向。4）螺旋桨竖直方向位移基本为负，水平方向正负交替且幅值相当，螺旋桨惯性力矩对轴系扭矩产生显著影响，其幅值与激振扭矩幅值相当。5）计算得螺旋桨相对角位移最大值为0.087rad；竖直向下位移最大值为2.86mm；轴向位移最大值为1.18mm，向主机方向偏移。为提高船舶推进系统可靠性及其优化设计提供了重要参考。
关键词：船舶推进系统，柴油机，激振力，动力学
ABSTRACT
In the dynamic investigation of propulsion shaft system formerly, main engine and shaft is analyzed separately. As a result the interaction of main engine, shaft and propeller could not be considered. In this thesis the propulsion shaft system is investigated. A multi-body dynamic model of propulsion shaft system including diesel engine, shaft, propeller and simple bearing block is established based on FE-Models and substructure technique, where different bodies are coupled by several non-linear coupling elements. The calculation is performed when combustion pressure and propeller exciting force is loaded on corresponding bodies at the state of power rating. The dynamic behavior of crankshaft, shaft and propeller is investigated within a complete engine cycle, as well as the influence of propeller exciting force to the system.
The results indicate that, as the affects of propeller exciting force, at drive end of crankshaft, the oscillation of axial displacement is intensified obviously, the relative angular displacement is increased 66%. Under different conditions, the trend and the maximum value of force and displacement of journals are consistent, but that is fluctuating tiny. So it is better to consider exterior load when analyzing the lubrication of crankshaft, for the model being more realizable. The force and displacement of shaft is analyzed, and that of propeller and shaft at rear stern bearing location is mainly analyzed. At rear stern bearing location, as influence of propeller load, the force and displacement is changed periodically along with the periodicity of exciting moment, and the value in vertical direction is bigger. The value of force at two ends is much bigger than that in middle, and the force close to propeller is about 5 times of that at the other end. The gravity and inertial moment of propeller affects dynamics obviously, the maximum value of inertial moment is almost equal to that of exciting torque, as a result the displacement in vertical direction is minus most time within an engine cycle, in horizontal direction the value alternate between plus and minus. For propeller, the maximum value of displacement in vertical direction is 2.86mm, and 1.18mm in axial direction to the engine, the maximum relative angular displacement value is 0.087radian. That provides an important reference for analyzing and improving the reliability of propulsion system and implementing its optimization.
Key words: propulsion shaft system, marine diesel, exciting force, dynamic
目 录
摘 要 I
ABSTRACT III
第一章 绪论 1
1.1 研究背景及意义 1
1.2 国内外研究现状 1
1.2.1动力学研究方面 2
1.2.2动力学建模方面 2
1.3 研究内容与方法 3
第二章 船舶推进系统模型 5
2.1 理论基础 5
2.1.1 有限元法 5
2.1.2 多体动力学基本理论 5
2.2 船舶推进系统有限元模型 7
2.2.1 曲轴 7
2.2.2 轴系 9
2.2.3 螺旋桨 11
2.2.4 轴承座 11
2.3 船舶推进系统多体动力学模型 13
2.3.1 推进系统组成及基本参数 14
2.3.2 定义体单元 16
2.3.3 定义非线性联接单元 17
2.3.4 推进系统多体动力学模型 22
2.4 本章小结 23
第三章 计算外部激振力 25
3.1 气缸燃气压力 25
3.2 计算螺旋桨激振力 26
3.2.1 螺旋桨扭转激振力 27
3.2.2 螺旋桨轴向激振力 28
3.2.3 螺旋桨弯曲激振力 29
3.3 本章小结 30
第四章 柴油主机动力学分析 31
4.1 曲轴全局运动分析 31
4.2 曲轴系动力学分析 34
4.2.1 活塞受力分析 34
4.2.2 曲轴受力分析 34
4.2.3 曲轴输出端分析 36
4.2.4 轴心轨迹分析 38
4.3 本章小结 41
第五章 推进轴系动力学分析 43
5.1 轴系分析 43
5.2 螺旋桨 46
5.3 本章小结 48
第六章 结论与展望 49-br..
