高压-微孔条件下不同黏度重质燃料油的喷雾与着火特性  

Spray and ignition characteristics of HFO with different viscosities under high pressure and micro hole conditions

作　　者：路秀伟 魏立江 黄文庆 Lu Xiuwei;Wei Lijiang;Huang Wenqing(Merchant Marine College,Shanghai Maritime University,Shanghai 201306,China)

机构地区：[1]上海海事大学商船学院,上海201306

出　　处：《内燃机学报》2025年第2期107-116,共10页Transactions of CSICE

基　　金：国家重点研发计划资助项目(2022YFB4301400);上海市科技计划资助项目(20DZ2252300).

摘　　要：燃用重质燃料油(HFO)的四冲程柴油机多被作为船舶的推进装置或发电原动机.为提高热效率、降低排放,提高喷射压力、缩小喷孔直径是喷射条件的发展趋势.采用大涡模拟(LES)求解湍流运动并耦合化学反应动力学,研究了高压-微孔条件下不同黏度HFO的喷雾与着火特性.结果表明:HFO的液相贯穿距离(LPL)几乎不受燃烧反应的影响,气相贯穿距离(VPL)因燃烧而降低,且降低幅度与HFO的黏度呈反比.低黏度HFO的喷雾形态与柴油类似,高黏度HFO的喷雾形态“窄而长”且靠近喷孔处的气相喷雾边缘呈“锯齿”状.黏度增加使燃烧相位提前,但放热率降低、放热峰值减小,火焰浮起长度(FLOL)缩短,火焰出现拖尾现象.稳态燃烧阶段的火焰扩散能力与燃料消耗速率和黏度无关.索特平均直径(SMD)与HFO的黏度呈正比,着火前SMD轻微上升,喷射结束后SMD显著上升.液滴总表面积的下降速率高于液滴总体积的下降速率是导致燃烧发生后SMD略有增加的根本原因.Four-stroke diesel engines burning heavy fuel oil(HFO)are often used as propulsion devices or power generators for ships.In order to improve the thermal efficiency and reduce emissions,increasing injection pressure and reducing nozzle hole diameter are the trends of injection conditions.The spray and ignition characteristics of HFO with different viscosities under high pressure and micro hole conditions were investigated.Large eddy simula-tion(LES)was used to solve the turbulent motion and chemical reaction kinetics were coupled.The results show that the liquid penetration length(LPL)of HFO is almost independent of the combustion,while the vapor penetration length(VPL)decreases due to combustion,and the decrease is inversely proportional to the viscosity of HFO.The spray morphology of low-viscosity HFO is similar to that of diesel,while the spray morphology of highviscosity HFO is narrow and long,having a jagged gas-phase spray edge near the nozzle.The increase in viscosity causes the combustion phase to advance,the heat release rate to slow down and its peak to decrease,the flame lift-off length(FLOL)to shorten and the flame to appear trailing.The flame spread ability and fuel consumption rate during the steady-state combustion phase are independent of the viscosity of HFO.The Sauter mean diameter(SMD)is proportional to the viscosity of HFO,with a slight increase before ignition and a significant increase after end of injection.The decrease rate of the total surface area of droplets is higher than the decrease rate of the total volume of droplets,which is the fundamental reason for the slight increase in SMD after ignition.

关 键 词：柴油机 重质燃料油 黏度 喷雾 着火 大涡模拟 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]