柴油机冷却水套内流体流动过程CFD分析

发布时间：2018-12-07 09:20

【摘要】：节能与环保的要求驱使现代柴油机采用更多新的高效清洁燃烧技术,柴油机的功率也得以不断强化,对于柴油机冷却系统的要求也越来越高。在冷却系统中,冷却水套承载着换热的重要功能。三维数值模拟CFD方法研究水套时具有设计成本低、周期短等优点,能有效面对市场竞争激烈导致的研发周期紧张的挑战,现在已逐渐成为柴油机行业研究冷却水套性能的基本工具。全文的主要工作如下:(1)在进行CFD分析前,首先通过试验方法得到柴油机水套某些关键点的参数,如流量、水压、水温等。根据试验数据和冷却水套三维模型等对柴油机水套进行CFD模拟分析,研究发现各缸流动不均匀,右侧六缸高于左侧六缸;缸盖水套内流速较低,存在流动死区;机体水套内流速低,中间也存在流动不佳区域。原柴油机水套需要进行改进。(2)根据CFD分析结果,对原方案进行改进,加大水泵流量,优化机体水套内进水口的结构(位置上移,进水方向调整为缸套的切向方向)。改进后各缸流量的均匀性有所改善,最大流量偏差值降至15.95%。缸盖水套排气道下方的冷却液流速明显增加,能达到2m·s-1;进、排气门座之间冷却液流速提升至0.6m·s-1;排气门座与喷油器孔之间的鼻梁区的冷却液流速提高至1.2m·s-1,中间区域达到2m·s-1。机体水套上部区域的流速达到0.5m·s-1以上,部分区域流速达到1 m·s-1;机体水套底部流速达到1 m·s-1的区域增多,进水口处的流速提高至0.8 m·s-1;机体水套中部流动不佳的区域减少,大部分区域的换热系数能3000W·(m2K)-1,特别是机体水套的上部区域,换热系数由1900~2000W·(m2K)-1提升为3000W·(m2K)-1。
[Abstract]:The requirement of energy saving and environmental protection drives modern diesel engine to adopt more new efficient and clean combustion technology, and the power of diesel engine is strengthened continuously, and the requirement of diesel engine cooling system is more and more high. In the cooling system, the cooling water jacket carries the important function of heat transfer. Three-dimensional numerical simulation CFD method has the advantages of low design cost, short cycle and so on, and can effectively face the challenge of the intense market competition in the research and development cycle. Now, it has gradually become the basic tool to study the performance of cooling water jacket in diesel engine industry. The main work of this paper is as follows: (1) before CFD analysis, the parameters of some key points of diesel engine water jacket, such as flow rate, water pressure, water temperature and so on, are obtained by test method. According to the experimental data and three dimensional model of cooling water jacket, the CFD simulation analysis of diesel engine water jacket shows that the flow of each cylinder is uneven, the right six cylinders are higher than the left six cylinders, the flow velocity in the cylinder head water jacket is lower, and there is a flow dead zone. The flow velocity in the water jacket is low and the flow is not good in the middle. (2) according to the results of CFD analysis, the original scheme is improved, the flow rate of water pump is increased, and the structure of the intake of water jacket is optimized (the position is moved up, the direction of the inlet is adjusted to the tangential direction of the cylinder liner). After the improvement, the flow uniformity of each cylinder is improved, the maximum flow deviation value is reduced to 15.95. The flow velocity of the coolant under the exhaust duct of the water jacket in the cylinder head increases obviously, and can reach 2m s-1.The velocity of the coolant between the inlet and the exhaust valve seat is raised to 0.6ms-1. The coolant velocity in the nasal beam area between the exhaust valve seat and the injector hole is increased to 1.2m s-1, and the intermediate region is up to 2m s-1. The velocity of the upper part of the water jacket is more than 0.5 m s ~ (-1), and the velocity of part of the area is 1 m ~ (-1). The velocity at the bottom of the water jacket increased to 1 m s ~ (-1), and the velocity at the inlet increased to 0.8 m ~ (-1). The heat transfer coefficient of most areas is 3000W (M2K) -1, especially in the upper part of the water jacket. The heat transfer coefficient is increased from 1900 ~ 2000W (M2K) -1 to 3000W (M2K) -1.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK423

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