船用柴油机缸套水冷.doc
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船用柴油机缸套水冷,摘 要冷却水的流动与传热直接影响到柴油机的冷却效率、高温零件的热负荷、整机的热量分配和能量利用。虽然从能量观点来看，柴油机的冷却是一种能量损失，但只有使柴油机受热零部件得到适度的冷却，使其温度维持在允许的范围内，才能保证其有效而可靠的工作。所以，对柴油机缸套冷却性能的研究对改善柴油机冷却效率和提高气缸缸套可靠性有重要的...
内容介绍
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摘 要
冷却水的流动与传热直接影响到柴油机的冷却效率、高温零件的热负荷、整机的热量分配和能量利用。虽然从能量观点来看，柴油机的冷却是一种能量损失，但只有使柴油机受热零部件得到适度的冷却，使其温度维持在允许的范围内，才能保证其有效而可靠的工作。所以，对柴油机缸套冷却性能的研究对改善柴油机冷却效率和提高气缸缸套可靠性有重要的意义。
在柴油机冷却问题的各种研究方法中，计算流体力学已经成为一个重要的手段。在冷却系统数值模拟过程中，由于传热边界条件难以确定，多数研究者仅仅考虑了冷却水的流动问题，在计算传热问题时，将冷却液的流动作为人为的边界条件进行处理。本文采用流固耦合的方法，建立冷却水腔与缸套之间三维耦合的模型，将冷却水流场与缸套温度场进行整体耦合，从而避免了对冷却水侧施加固定壁温及冷却液流动的边界条件。利用FLUENT软件自带的UDF功能对燃气侧换热系数及温度进行编程，从而实现了对燃气侧施加第三类边界条件，通过固体与流体之间的耦合，可以使施加的边界条件更为准确。
用耦合的方法计算分析了某船用柴油机内冷却水的流动、温度分布、压力分布以及缸套温度场的分布情况，并将计算结果与传统的固定边界条件结果进行对比分析。分析结果表明，通过流场与温度场的耦合计算，能够得到更加准确的冷却水流动情况、压力分布以及冷却水出口温度，同时还能得出缸套温度场的分布情况，说明固体与流动之间耦合的数值模拟能够更客观的反映柴油机冷却系统的流动与传热问题，并且能为冷却系统的优化设计提供重要的参考依据。
关键词 柴油机；冷却系统；流动与传热；数值模拟；耦合计算
Abstract
The flow and heat transfer of cooling water has directly effect on the cooling efficiency of diesel engine, the heat load of high temperature parts and the heat distribution and energy use of whole diesel engine. Although, at the view of energy, the engine cooling is an energy loss process, it is the necessary process during the work of diesel engine. Because it is necessary to keep the temperature of the high temperature parts within the permissible range, in order to ensure the effective and reliable work of the diesel engine. Generally speaking, the research on cooling performance of diesel engine cylinder has great significance on improving the diesel engine’s cooling efficiency and the reliability of cylinder liner.
The computational fluid dynamics is one of the most important research methods in the research on diesel engine cooling problems. During the numerical simulation process of cooling system, because of the boundary conditions of heat transfer is difficult to determine, most researchers only considered the problem of cooling water flow. In addition, when calculated the heat transfer, they treated the coolant flow as artificial boundary condition. In this paper, the fluid-structure coupling method was used; the three-dimensional coupling model of cooling water chamber and cylinder was established. In the model, the cooling water flow field and cylinder temperature field was coupled, in which way the set of fixed wall temperature and coolant flow boundary condition were avoided. Using the UDF module of FLUENT to program the transfer coefficient and temperature at the gas side, and then the third type boundary condition exerted on the gas side was realized. It made the exertion of the boundary conditions more accurate, by coupling between fluids and solid.
The coupling method was used to analyze the cooling water flow field, temperature distribution, pressure distribution and the cylinder liner temperature distribution, and compare the calculation results and the traditional fixed boundary condition calculation results. The more accurate flow condition of cooling water, pressure distribution, the cooling water temperature at outlet, and the cylinder liner temperature distribution were obtained, through calculating of flow field and temperature field. The calculation results show that the coupling numerical simulation method could describe the flow and heat transfer problem of diesel engine more objectively. And the calculation results could provide important reference for the optimized design of cooling system.
Keywords Cooling system; Flow and transfer; Numerical simulation; Coupling calculation
目 录
摘 要 I
Abstract III
第1章 绪 论 1
1.1 课题来源及研究意义 1
1.2 柴油机热负荷研究现状 1
1.2.1 实验测量 1
1.2.2 数值仿真计算 2
1.2.2.1缸套传热微分方程及边界条件计算发展现状 2
1.2.2.2数值计算方法发展现状 4
1.3 有限体积法在发动机设计中的应用 6
1.4 有限体积法在发动机设计中的缺陷 6
1.5本研究的主要内容及意义 7
第2章 流固耦合 9
2.1 流固耦合理论 9
2.2 用户自定义函数(UDF) 10
2.3本章小结 11
第3章 数值模拟计算模型及边界条件 12
3.1 柴油机参数介绍 13
3.2 冷却水流动控制方程及其求解条件 13
3.2.1 冷却水流动控制方程 13
3.2.2 湍流模型 14
3.2.3 流动边界条件 15
3.3 导热微分方程及其求解条件 16
3.3.1 导热微分方程 16
3.3.2 方程的求解条件 18
3.3.3 传热边界条件 18
3.4 缸套温度场计算 19
3.4.1 缸套温度场计算的换热微分方程 19
3.4.2 燃气侧边界条件及UDF的应用 19
3.4.3 缸套与机体和缸盖接触面之间的换热系数 24
3.4.4 缸套外侧冷却水换热系数的分布 24
3.5 本章小结 25
第4章 模拟计算与分..
冷却水的流动与传热直接影响到柴油机的冷却效率、高温零件的热负荷、整机的热量分配和能量利用。虽然从能量观点来看，柴油机的冷却是一种能量损失，但只有使柴油机受热零部件得到适度的冷却，使其温度维持在允许的范围内，才能保证其有效而可靠的工作。所以，对柴油机缸套冷却性能的研究对改善柴油机冷却效率和提高气缸缸套可靠性有重要的意义。
在柴油机冷却问题的各种研究方法中，计算流体力学已经成为一个重要的手段。在冷却系统数值模拟过程中，由于传热边界条件难以确定，多数研究者仅仅考虑了冷却水的流动问题，在计算传热问题时，将冷却液的流动作为人为的边界条件进行处理。本文采用流固耦合的方法，建立冷却水腔与缸套之间三维耦合的模型，将冷却水流场与缸套温度场进行整体耦合，从而避免了对冷却水侧施加固定壁温及冷却液流动的边界条件。利用FLUENT软件自带的UDF功能对燃气侧换热系数及温度进行编程，从而实现了对燃气侧施加第三类边界条件，通过固体与流体之间的耦合，可以使施加的边界条件更为准确。
用耦合的方法计算分析了某船用柴油机内冷却水的流动、温度分布、压力分布以及缸套温度场的分布情况，并将计算结果与传统的固定边界条件结果进行对比分析。分析结果表明，通过流场与温度场的耦合计算，能够得到更加准确的冷却水流动情况、压力分布以及冷却水出口温度，同时还能得出缸套温度场的分布情况，说明固体与流动之间耦合的数值模拟能够更客观的反映柴油机冷却系统的流动与传热问题，并且能为冷却系统的优化设计提供重要的参考依据。
关键词 柴油机；冷却系统；流动与传热；数值模拟；耦合计算
Abstract
The flow and heat transfer of cooling water has directly effect on the cooling efficiency of diesel engine, the heat load of high temperature parts and the heat distribution and energy use of whole diesel engine. Although, at the view of energy, the engine cooling is an energy loss process, it is the necessary process during the work of diesel engine. Because it is necessary to keep the temperature of the high temperature parts within the permissible range, in order to ensure the effective and reliable work of the diesel engine. Generally speaking, the research on cooling performance of diesel engine cylinder has great significance on improving the diesel engine’s cooling efficiency and the reliability of cylinder liner.
The computational fluid dynamics is one of the most important research methods in the research on diesel engine cooling problems. During the numerical simulation process of cooling system, because of the boundary conditions of heat transfer is difficult to determine, most researchers only considered the problem of cooling water flow. In addition, when calculated the heat transfer, they treated the coolant flow as artificial boundary condition. In this paper, the fluid-structure coupling method was used; the three-dimensional coupling model of cooling water chamber and cylinder was established. In the model, the cooling water flow field and cylinder temperature field was coupled, in which way the set of fixed wall temperature and coolant flow boundary condition were avoided. Using the UDF module of FLUENT to program the transfer coefficient and temperature at the gas side, and then the third type boundary condition exerted on the gas side was realized. It made the exertion of the boundary conditions more accurate, by coupling between fluids and solid.
The coupling method was used to analyze the cooling water flow field, temperature distribution, pressure distribution and the cylinder liner temperature distribution, and compare the calculation results and the traditional fixed boundary condition calculation results. The more accurate flow condition of cooling water, pressure distribution, the cooling water temperature at outlet, and the cylinder liner temperature distribution were obtained, through calculating of flow field and temperature field. The calculation results show that the coupling numerical simulation method could describe the flow and heat transfer problem of diesel engine more objectively. And the calculation results could provide important reference for the optimized design of cooling system.
Keywords Cooling system; Flow and transfer; Numerical simulation; Coupling calculation
目 录
摘 要 I
Abstract III
第1章 绪 论 1
1.1 课题来源及研究意义 1
1.2 柴油机热负荷研究现状 1
1.2.1 实验测量 1
1.2.2 数值仿真计算 2
1.2.2.1缸套传热微分方程及边界条件计算发展现状 2
1.2.2.2数值计算方法发展现状 4
1.3 有限体积法在发动机设计中的应用 6
1.4 有限体积法在发动机设计中的缺陷 6
1.5本研究的主要内容及意义 7
第2章 流固耦合 9
2.1 流固耦合理论 9
2.2 用户自定义函数(UDF) 10
2.3本章小结 11
第3章 数值模拟计算模型及边界条件 12
3.1 柴油机参数介绍 13
3.2 冷却水流动控制方程及其求解条件 13
3.2.1 冷却水流动控制方程 13
3.2.2 湍流模型 14
3.2.3 流动边界条件 15
3.3 导热微分方程及其求解条件 16
3.3.1 导热微分方程 16
3.3.2 方程的求解条件 18
3.3.3 传热边界条件 18
3.4 缸套温度场计算 19
3.4.1 缸套温度场计算的换热微分方程 19
3.4.2 燃气侧边界条件及UDF的应用 19
3.4.3 缸套与机体和缸盖接触面之间的换热系数 24
3.4.4 缸套外侧冷却水换热系数的分布 24
3.5 本章小结 25
第4章 模拟计算与分..
