柴油机喷油器喷孔内流穴蚀风险分析

Risk Analysis of Cavitation Erosion for Diesel Engine Injector Nozzle Holes

针对柴油机喷油器喷孔内空化流动及穴蚀磨损问题,建立了孔内燃油流动的仿真三维模型,并且通过可视化试验验证了模型的准确性。在R_(rs)冲蚀风险预测模型的基础上,将微射流速度、水锤压力和侵蚀强度系数引入公式,建立了喷油器喷孔内流穴蚀风险预测模型,实现了穴蚀损伤位置的定量表征。采用该模型研究了喷孔不同当量入口圆角半径、不同喷孔倾角和不同当量表面粗糙度对喷油器喷孔穴蚀磨损的影响。计算结果表明,穴蚀磨损区域主要位于喷孔入口处和喷孔上侧表面,且当量入口圆角半径对穴蚀磨损的影响大于当量表面粗糙度和喷孔倾角,因此可以优先考虑增加喷孔入口圆角半径以减小穴蚀磨损,提升喷油器寿命。

Aiming at the cavitation flow and cavitation wear problems in injector nozzle holes of diesel engine,a 3D simulation model of fuel flow inside nozzle hole was established,and the accuracy of model was verified by visual test.Based on R_(rs)erosion risk prediction model,the microjet velocity,water hammer pressure and erosion intensity coefficient were introduced into the formula to establish a prediction model of cavitation risk in injector nozzle holes.The quantitative characterization of the location of cavitation damage was realized.The model was used to study the effects of different equivalent inlet radius,different inclination angles and different equivalent surface roughness on the cavitation wear of injector nozzle holes.The calculation results show that the cavitation wear area is mainly located at the entrance and upper surface of nozzle hole,and the effect of the equivalent inlet radius on the cavitation wear degree is greater than that of the equivalent surface roughness and the nozzle inclination angle.Therefore,the priority can be given to increasing the corner radius of nozzle inlet to reduce the hole erosion wear and hence improve the life of injector.