【作者】 李迎；

【导师】 俞小莉；

【作者基本信息】 浙江大学 ， 动力机械与工程， 2006， 博士

【摘要】 内燃机受热零部件的传热和热状态研究是内燃机热疲劳可靠性和热平衡研究的基础。随着现代计算技术的发展，基于控制容积法的有限元方法已经可以实现流体与固体的耦合传热与流动数值仿真。本文在分析发动机主要受热零件传热仿真研究特点的基础上，建立了内燃机活塞组—缸套—冷却水—机体流固耦合系统。耦合系统包括了固体与固体之间的耦合传热，也包括了流体和固体之间的耦合传热与流动。将原来单个零件传热仿真时的外边界条件变为内边界，由有限元软件进行内部处理，使传热仿真变得更合理更简单。应用所建立的耦合系统，对算例柴油机稳态工况下的耦合传热、周期性瞬态传热以及冷启动、外特性和负荷特性变工况时的瞬态传热与流动进行了数值仿真。在此基础之上，与内燃机工作过程程序结合，对算例柴油机的整机热平衡进行了仿真，并与实验结果做了对比分析。 本文的主要工作内容可以概括为以下几个部分： 1) 通过对内燃机主要受热零件传热特性的分析，针对干缸套和湿缸套不同的流动与传热耦合特点，建立了两种机型的活塞组—缸套—冷却水—机体流固耦合传热模型。以两种机型的耦合系统作为算例，对其额定工况和最大转矩工况下的稳态传热与流动进行了数值仿真计算。与额定工况下活塞和缸套温度场实验测量结果比较，数值仿真和实验结果误差较小，验证了所建立仿真模型的合理性。 2) 针对内燃机传热问题的高频周期性，分析了缸内燃气热状态在一个循环内的剧烈变化和活塞的往复运动特性，建立了活塞—缸套动接触传热模型。并进行了活塞组—缸套—冷却水—机体耦合系统的周期性瞬态传热仿真计算，得到了耦合传热条件下，燃烧室主要零部件表层高周热负荷的基本分布规律，并分析了缸内工作的周期性对耦合传热系统的整体影响。 3) 对干缸套算例柴油机的冷启动工况、外特性和额定转速下的负荷特性等变工况的耦合系统瞬态传热与流动进行了仿真计算。得到了耦合系统的温度场和流场在发动机工况变动时随时间变化的发展规律。该规律性对于制定合理的热管理策略提供了依据。 4) 在活塞组—缸套—冷却水—机体耦合系统传热仿真结果基础之上，在原有的内燃机工作过程计算程序中增加了热平衡计算模块，对算例柴油机沿外特性和额定转速下的负荷特性运行时的整机热平衡状态进行了模拟计算，并与实机实验结果进行了对比分析。结果表明，使用流固耦合传热方法计算内燃机热平衡是可行的，结果与实机测量结果非常接近。更多还原

【Abstract】 It is one of most important groundworks to study heat transfer and thermal status of engines’ components for engine thermal fatigue and thermal equilibrium investigation. Finite volume method (FVM) makes it realizable to simulate the coupled heat transfer between liquid and solid. Based on analysis of heat transfer simulation characters between main engine heated parts, piston-liner-coolant-body fluid-solid coupled system is created. This coupled system concludes coupled heat transter between solid and solid, besides coupled heat transfer and flow simulation between fluid and solid. Outer boundary conditions between single parts are converted to inner boundary conditions processed through finite software, so that heat transfer simulation becomes more reasonable and simpler. With the coupled simulation model, heat transfer of stable working state, periodic transient working state and exchanging working state including cool start, full load and full speed were simulated. Futhermore, combined with engine working process simulation code, engine heat balance was worked out.Major contents of this thesis can be list as:1. By heat transfer feature analysis of enignes’ key heated components, piston-liner-coolant-body fluid-solid coupled heat transfer simulation model for dryliner and wetliner were constructed. Stable heat transfer and fluid flow in rated mode and maximum torque mode were conducted. The temperature fields of piston and liner in rated mode were measured, which verified that the simulation model is reasonable.2. For the high-frequency periodic character of engines’ heat transfer, the thermal status of gas in cylinder changing periodically and piston’s back and forth movement was analysed and dynamic contact heat transfer model for the piston andliner was set up. Periodic transient heat transfer simulations of piston-liner-coolant-body fluid-solid were calculated. The primary distribution principles of temperature field of cylinder’s key components were worked out. The integral influence of engines’ periodic to the coupled system was anlysed.3. The transient heat transfer and fluid flow of coupled system during engine cool start, full load and full speed were simulated. The development principle of coupled system’s temperature field and fluid flow according as time was worked out, which is one of the major reliance to establish a reasonable heat management strategy.4. Based on former heat transfer simulation work, a heat balance simulation module was coded and heat balance of the engine when working through full load and full speed feature were simulated. By comparison to the test result, it is concluded that the coupled simulation system model is a reasonable and efficient method for engines’ heat transfer.It is one of most important groundworks to study heat transfer and thermal status of engines’ components for engine thermal fatigue and thermal equilibrium investigation. Finite volume method (FVM) makes it realizable to simulate the coupled heat transfer between liquid and solid. Based on analysis of heat transfer simulation characters between main engine heated parts, piston-liner-coolant-body fluid-solid coupled system is created. This coupled system concludes coupled heat transter between solid and solid, besides coupled heat transfer and flow simulation between fluid and solid. Outer boundary conditions between single parts are converted to inner boundary conditions processed through finite software, so that heat transfer simulation becomes more reasonable and simpler. With the coupled simulation model, heat transfer of stable working state, periodic transient working state and exchanging working state including cool start, full load and full speed were simulated. Futhermore, combined with engine working process simulation code, engine heat balance was worked out.Major contents of this thesis can be list as:1. By heat transfer feature analysis of enignes’ key heated components, piston-liner-coolant-body fluid-solid coupled heat transfer simulation model for dryliner and wetliner were constructed. Stable heat transfer and fluid flow in rated mode and maximum torque mode were conducted. The temperature fields of piston and liner in rated mode were measured, which verified that the simulation model is reasonable.2. For the high-frequency periodic character of engines’ heat transfer, the thermal status of gas in cylinder changing periodically and piston’s back and forth movement was analysed and dynamic contact heat transfer model for the piston andliner was set up. Periodic transient heat transfer simulations of piston-liner-coolant-body fluid-solid were calculated. The primary distribution principles of temperature field of cylinder’s key components were worked out. The integral influence of engines’ periodic to the coupled system was anlysed.3. The transient heat transfer and fluid flow of coupled system during engine cool start, full load and full speed were simulated. The development principle of coupled system’s temperature field and fluid flow according as time was worked out, which is one of the major reliance to establish a reasonable heat management strategy.4. Based on former heat transfer simulation work, a heat balance simulation module was coded and heat balance of the engine when working through full load and full speed feature were simulated. By comparison to the test result, it is concluded that the coupled simulation system model is a reasonable and efficient method for engines’ heat transfer.更多还原