某柴油喷油嘴新冲蚀寿命预测模型及瞬态特性数值模拟  

Prediction Model of New Erosion Life and Numerical Simulation of Transient Characteristics of a Diesel Fuel Injector

作　　者：许磊 张翼[1] 徐春龙 宋猛 庞浩宇 张宇[1] 唐诗泽 雷丽军 XU Lei;ZHANG Yi;XU Chun-long;SONG Meng;PANG Hao-yu;ZHANG Yu;TANG Shi-zhe;LEI Li-jun(School of Energy and Power Engineering,North University of China,Taiyuan 030051,China;China North Engine Research Institute,Tianjin 300400,China)

机构地区：[1]中北大学能源与动力工程学院,太原030051 [2]中国北方发动机研究所,天津300400

出　　处：《表面技术》2023年第1期121-131,177,共12页Surface Technology

基　　金：山西省科技重大专项(MQ2016-02-01);山西省“百人计划”创新团队项目资助。

摘　　要：目的针对柴油喷油嘴喷孔内部空化现象及冲蚀磨损问题,建立了考虑近壁面不同边界层内群气泡溃灭产生冲蚀影响的柴油喷油嘴瞬态特性仿真模型。探究柴油喷油嘴内部冲蚀磨损程度的影响因素,并对喷孔内部冲蚀磨损寿命进行预测。方法首先,采用MATLAB对不同近壁面距离的空化泡对壁面作用压力及射流速度进行函数拟合,结合传统经验公式,推导了可考虑距壁面不同距离的群空泡阻力修正经验公式。其次,利用Fluent中UDF建立了基于阻力修正经验公式以及网格自适应算法的有限元模型,用Rrs冲蚀风险预测模型和冲蚀疲劳试验结果对本文提出的新模型进行验证。在此基础上讨论了喷嘴孔圆锥度Kfac及动态特性对喷孔冲蚀磨损的影响。结果Rrs冲蚀磨损风险预测模型和冲蚀磨损疲劳试验结果与本文提出的新模型结果有较好的一致性,证明了该新模型的可行性。有限元仿真结果显示,当喷嘴形状相同时,随着针阀向上移动,空化现象被有效地抑制,逐渐向喷孔的入口处收缩,其上最大射流速度和水锤压力会略微增加,但总体空化区域多集中于喷孔入口上表面处。随着喷嘴几何尺寸从Kfac0增加至Kfac2、Kfac4,其上喷孔的气泡溃灭最大微射流速度及最大水锤压力分别减少11.29%、1.4%。当无量纲距离δ=1.3时,其最大速度和压力值仅为无量纲距离δ=1.0时的2.6%,故可忽略无量纲距离δ>1.3时的气泡溃灭对壁面的冲蚀磨损影响。随着喷嘴几何尺寸从Kfac0增加至Kfac2、Kfac4,其上喷孔内壁面最小寿命分别提升了18.17%及32.32%。结论喷嘴孔圆锥度Kfac及动态特性均对近壁面空化冲蚀磨损程度产生影响。总体空化冲蚀磨损区域多集中于喷孔入口上表面处,可对此采取措施以提高总体喷嘴寿命,疲劳寿命计算时可忽略距壁面无量纲距离δ>1.3时气泡对壁面产生的影响,喷嘴喷孔圆锥度的增加可降低喷�Aiming at the cavitation phenomenon and erosion wear problem in the nozzle hole of diesel fuel injector,by introducing the research theory of the pressure and jet velocity of cavitation bubbles with different distance near the wall,the traditional empirical formula is modified,and the transient characteristic simulation model of diesel fuel injector considering the erosion effect caused by the collapse of group bubbles in different boundary layers near the wall is established.Using the method of simulation,the influencing factors of the internal erosion wear degree of diesel fuel injection nozzle are explored,and the erosion wear life of the nozzle hole is predicted.Firstly,based on the research conclusions of the pressure and jet velocity of cavitation bubbles with different distance to the wall,the function fitting of the pressure and jet velocity of cavitation bubbles with different distance to the wall is carried out by using MATLAB software.Combined with the traditional empirical formula,the resistance correction empirical formula of group cavitation considering different distances from the wall surface is derived.Secondly,the finite element model based on resistance correction empirical formula and grid adaptive algorithm is established by using UDF in fluent.The Rrscavitation risk prediction model is established by using the theory of representing erosion risk by steam mass condensation rate.The new model proposed in this paper is verified by Rrscavitation risk prediction model and cavitation fatigue test results,It is proved that the new model proposed in this paper has good accuracy.Based on the calculation results of this model,the effects of nozzle orifice conicity Kfacand needle valve dynamic characteristics on orifice erosion wear are discussed.As the geometric size of the nozzle increases from Kfac0 to Kfac2 and Kfac4,the cross-sectional area of the orifice becomes smaller along the flow direction,the reflux near the wall and the separation of the boundary layer are restrained,the cavitation will be

关 键 词：空化流动 水锤压力 喷嘴喷孔 冲蚀 寿命预测 

分 类 号：TH117[机械工程—机械设计及理论]