柴油机气缸套冷却水空化流的三维数值模拟  

3D Numerical Simulation of Cooling-water Cavitation Flow of Cylinder Liner for Diesel Engine

作　　者：夏冬生[1] 张会臣[1] 于彦[1] 

机构地区：[1]大连海事大学机械工程系,大连116026

出　　处：《机械工程学报》2011年第22期167-173,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(50975036;50675024)

摘　　要：基于计算流体动力学(Computational fluid dynamics,CFD)方法应用动网格技术采用两相混合流体完整空化湍流模型,对某型柴油机气缸套主推侧的冷却水空化流进行非定常数值模拟。计算结果揭示缸套空蚀发生机理和冷却水流场特性变化,预测缸套冷却水的空化部位和程度。与缸套空蚀的统计结果对比,建立的数学模型是可靠的。结果表明,缸套附近流场的绝对压力和气相体积分数均具有周期性变化特性,且与缸套的振动周期一致。缸套附近冷却水空化流的流场特性不均匀。贴近变形最大的缸套壁区(缸套壁的中上区域)处流场压力和气相体积分数波动剧烈。此局部流场脉冲压力峰值达到约350 kPa,气相体积分数在5.8%～0.4%波动。较强脉冲压力的作用导致此壁区空蚀严重。振动频率和振幅分别增大30%,变形最大壁区附近流场压力峰值分别增加55%和15%。进口流速和流向对冷却水空化特性有一定影响,最大变形壁区气相体积分数峰值随流场平均流速的增大而增加。缸套振动的加速度是影响冷却水空化流流场特性的关键因素。Unsteady numerical simulation of cooling-water cavitation flow around the major-thrust side of cylinder liner for a diesel engine is carried out by using a mixture two-phase flow model and a full cavitation model.The cavitaion-erosion mechanism and properties of water cavitation flow are revealed.The experimental statistics results of cavitation-erosion location and degree of cylinder liners validate the simulated results.The results show that the absolute pressure and vapor volume fraction of water flow,proximity to the liner,vary periodically in consistence with the liner-wall vibration.The pressure and vapor volume fraction seriously fluctuate in the local flow proximity to the maximum deformed wall（the middle upper zone）.The impulse peak pressure reaches 350 kPa and vapor fraction varies 5.8%～0.4% in this local flow.The significant effect of impulse pressure leads to the serious cavitation erosion on this wall zone.As the liner-vibration frequency and amplitude increase 30%,the pressure peak increases 55% and 15% on the maximum deformed wall,respectively.As the inlet-flow velocity and direction are varied,the peak value of vapor volume fraction of flow field on the maximum deformed wall increases with rising of the average velocity of water flow.The liner-vibration acceleration is a key factor affecting properties of cooling-water cavitation flow.

关 键 词：缸套 空化 计算流体力学 流场分析 

分 类 号：TK428[动力工程及工程热物理—动力机械及工程]