某高原柴油机缸盖三相耦合换热及应力分析

发布时间：2018-02-01 02:00

本文关键词： 高原环境柴油机冷却系统多场耦合　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着我国西部大开发战略的深入,高原交通运输能力成为发展的重点和难点。柴油机作为重型载重货车及内燃机车的核心也需要适应高原环境条件,为高原经济发展做出贡献。柴油机的高原热平衡能力作为高原适应性的一个分支越来越多的得到各界的重视,高原地区低压、低温的特点对柴油机冷却系统提出了苛刻的要求。针对高原柴油机热管理的各类实验及数值模拟方法也逐步完善,成为开发设计高原柴油机冷却系统的不可或缺的手段。本文以某12缸V型高原柴油机为研究对象,运用专业CFD模拟软件FLUENT对冷却系统的流动和换热能力做了评估,并联合ANSYS-Workbench的静力学分析模块实现对单缸缸盖的热-机耦合应力分析。首先分析了高海拔地区冷却水物性参数的变化,并针对4个不同海拔选取了对应浓度的乙二醇溶液作为该海拔下的冷却介质,利用该结果对不同海拔下的整机冷却水套进行了绝热流动模拟,并对比海拔2000m的模拟结果与试验值进行有效性验证。然后选取流动效果最差的海拔5000m下的第6缸建立气缸盖-冷却水套-气缸套流固耦合模型研究缸体换热能力。之后提出将进排气流动换热加入耦合系统构成气-液-固三相流固耦合模型进行综合换热模拟,并将结果与不考虑进排气流动时缸盖温度分布及缸盖测点温度进行对比,发现加入进排气后的缸盖温度更加接近实际情况。然后针对水套局部流动不畅提出了结构改进措施,对改进后系统再次进行耦合换热模拟,发现改进后火力面水套排气侧伸出部流动被激活,缸盖对应部位温度明显下降。最后利用ANSYS-Workbench对改进后的缸盖进行了热-机耦合应力分析和强度校核,结果表明在导入热载荷、机械应力及装配约束的联合作用下缸盖满足强度要求。
[Abstract]:With the development of China's western development strategy, plateau transportation capacity has become the focus and difficulty of development. As the core of heavy truck and diesel locomotive, diesel engine also needs to adapt to the plateau environment. As a branch of plateau adaptability, diesel engine's plateau heat balance ability has been paid more and more attention to, plateau area low pressure. The characteristics of low temperature put forward harsh requirements for diesel engine cooling system. All kinds of experimental and numerical simulation methods for plateau diesel engine thermal management have been gradually improved. It has become an indispensable means to develop and design the cooling system of plateau diesel engine. In this paper, a 12-cylinder V-type plateau diesel engine is taken as the research object. The flow and heat transfer capacity of the cooling system was evaluated with the professional CFD simulation software FLUENT. Combined with the statics analysis module of ANSYS-Workbench, the thermal-mechanical coupling stress analysis of single cylinder head is realized. Firstly, the variation of physical parameters of cooling water at high altitude is analyzed. At four different elevations, the corresponding concentration of ethylene glycol solution was chosen as the cooling medium at the same altitude, and the adiabatic flow of the cooling water jacket at different altitudes was simulated by using the results. The simulation results of 2000m above sea level and the experimental results were compared to verify the validity of the model. Then, the sixth cylinder with the worst flow effect was selected to establish the fluid-solid coupling model of cylinder head, cooling water jacket and cylinder liner. The heat transfer capacity of cylinder block is studied. After that, the gas-liquid-solid three-phase fluid-solid coupling model is proposed to simulate the heat transfer by adding the inlet and exhaust flow heat transfer into the coupled system. The results are compared with the temperature distribution of the cylinder head and the temperature of the measuring point of the cylinder head without considering the inlet and exhaust flow. It is found that the cylinder head temperature is closer to the actual situation after the inlet and exhaust. Then the structural improvement measures are put forward in view of the local flow of the water jacket, and the coupling heat transfer simulation of the improved system is carried out again. It is found that the flow of the outstretched side of the water jacket side of the firepower surface is activated after the improvement. Finally, the thermal-mechanical coupling stress analysis and strength check of the improved cylinder head are carried out by using ANSYS-Workbench. The results show that the heat load is introduced. The combined action of mechanical stress and assembly constraint satisfies the strength requirement of cylinder head.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK423

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