船用低速柴油机喷嘴内流及初次破碎机理研究  

Investigation on the In-Nozzle Flow and Primary Breakup of Marine Low-Speed Engines

作　　者：潘业俊 刘灿旭 刘红[1] 尹洪超[1] Pan Yejun;Liu Canxu;Liu Hong;Yin Hongchao(Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学海洋能源利用与节能教育部重点实验室,辽宁大连116024

出　　处：《内燃机学报》2022年第5期412-419,共8页Transactions of Csice

基　　金：国家自然科学基金资助项目(51961135105);天津大学实验室开放基金资助项目(K2018-04).

摘　　要：基于OpenFOAM平台,采用多流体-准VOF模型对某船用低速柴油机的喷嘴内流和初次破碎进行数值研究,应用气-液相间动量交换模型考虑气动力对雾化的干扰,大涡模拟(LES)求解混合流体的湍流方程,修正的空化子模型考虑喷孔内部空化现象.结果表明:较传统的流体体积函数(VOF)模型而言,多流体-准VOF模型具有更高的计算精度,在准确预测伞形射流尖端的同时,清晰呈现了射流表面波的生成和发展以及液带、液滴剥离的完整过程.随着喷射压力的升高,喷孔出口湍流效应加剧,同时高速度梯度使气-液相间的拖曳阻力大幅增强,主喷雾区由此产生更强的轴向涡流和直径更小的射流,伞形尖端亦剥离出数量更多、尺寸更小的环形液带和液滴,呈现出更好的雾化效果.而喷孔内流对初次破碎的影响在其发展为超空化后不再随喷射压力的升高而发生变化.An improved multi-fluid model,named multi-fluid-quasi-VOF model,was used to carry out a numerical study on the in-nozzle flow and the primary breakup of a marine low-speed diesel engine.In the model,the gasliquid momentum exchange model was used to consider the interference of aerodynamic forces on atomization,the large eddy simulation(LES)was used to solve the turbulence equation of the mixed fluid,and a modified cavitation sub-model was used to consider the cavitation inside the nozzle orifice.The results show that the multi-fluid-quasi-VOF model has higher calculation accuracy than the traditional VOF model.It can not only predict the umbrella tip accurately,but also clearly present the complete process of the generation and development of jet surface waves and the stripping of liquid ligaments and droplets.After increasing the injection pressure,the turbulence effect at the nozzle outlet is intensified and the high velocity gradient greatly enhances the drag force between the gas and the liquid phases.As a result,the main spray zone produces stronger axial vortexes and a smaller jet,while more and smaller annular liquid ligaments and droplets are peeled off from the umbrella-shaped tip,which shows a better atomization effect.The influence of the internal cavitation on the primary breakup will no longer change with the increase of injection pressure after it develops into supercavitation.

关 键 词：船用低速柴油机 多流体 大涡模拟 初次破碎 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]