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关键结构参数对压电式喷油器喷射特性的影响 总被引:1,自引:0,他引:1
利用Matlab/Simulink软件,建立了压电驱动器非线性动力学模型,同时耦合其他机-液部分,建立了完整的压电喷油器电-机-液模型,并试验验证了模型的准确性.系统分析了驱动器预紧力、进/出油孔直径、旁通油孔直径、控制腔容积、控制活塞直径和针阀弹簧预紧力等参数对喷油特性和针阀响应特性的影响,并建立了结构参数灵敏度量化指标,对各部件结构参数进行灵敏度量化分析.结果表明:该喷油器特有的旁通油道可有效地减少针阀关闭延迟,下降时间缩短了0.2 ms,有利于喷油器快速断油;适当增大进/出油孔的孔径比可提高针阀开启速度、缩短针阀下降时间;在各结构参数的许可范围内,针阀控制活塞直径和进/出油孔直径在喷油器喷油量以及针阀响应过程的各个时期影响权重最大,旁通油孔直径和控制腔容积主要影响针阀的回位阶段,喷孔直径对针阀上升和下降过程影响较小,但更大程度上改变了循环喷油量. 相似文献
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喷孔几何特征对变截面喷油孔空穴流动状态的影响 总被引:1,自引:0,他引:1
采用混合多相流模型及空穴模型相结合的方法,对喷油嘴激光打孔过程形成的变截面喷油孔内空穴流动现象进行数值模拟,重点分析喷孔几何特征对空穴流动状态的影响规律.结果表明,变截面喷孔内喷孔截面收缩或者扩张的程度及位置对孔内燃油空穴流动状态具有重要影响.截面收缩型的喷孔可在出口形成更大的空穴强度分布,利于促进燃油的初次分裂及雾化.截面扩张型喷孔可使得出口燃油速度分布更均匀,出口平均速度增大,从而提高流量系数;研究还发现,相对于直喷孔,变截面喷油孔内空穴流动状态对孔入口倒角变化的敏感性减小,这将有利于提高多孔喷嘴各孔流量及雾化的均匀性. 相似文献
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柴油机喷孔内部空化效应的可视化实验研究 总被引:1,自引:0,他引:1
柴油机喷孔内空化现象显著影响燃油雾化质量.针对目前广泛应用的VCO型喷嘴,设计大尺度透明喷嘴稳态实验系统,全面研究了无量纲数、雷诺数、喷嘴射流参数和结构参数对喷嘴内空化过程的影响.结果表明,空化数对空化剧烈程度影响显著,雷诺数对空化剧烈程度影响小于空化数;射流参数直接影响流体流动状态,增大入口压力、减小出口压力和针阀升程能使喷孔内的空化现象显著增强;结构参数决定喷孔内流动形式,增大喷孔倾角、直径和长径比,采用入口圆角等措施会抑制空化的产生. 相似文献
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The internal flow of diesel nozzles has a strong influence on the subsequent spray and atomization characteristics. A flow visualization experiment system equipped with enlarged transparent nozzles was set up to investigate the effect of different nozzle structures and different nozzle enlarged scales on cavitating flow and subsequent spray characteristics. Significant parameters of internal flow including critical pressure of cavitation inception, critical pressure of hydraulic flip, discharge coefficient, Reynolds number, flow rate and cavitation distribution were fully investigated during the experiments. Experimental results show that the nozzles with small length/diameter ratios at the same orifice diameter were more inclined to cavitate and had higher discharge coefficient than that of nozzles with large length/diameter ratios. Cavitating flow in nozzles with different sac volume structures may incur different spray characteristics in the near-nozzle field and it is the internal cavitating flow that induces the asymmetry of subsequent spray. The investigations indicate that the critical pressure of hydraulic flip and discharge coefficient of nozzles under different needle lifts were quite different even under the same boundary conditions and the nozzle flow characteristics have been greatly influenced by the hydraulic flip phenomenon. Two types of cavitation were observed in nozzles with different scaled-up times and the string cavitation was found in three times scaled-up nozzle, while the cloud cavitation bubbles were appeared in five and eight times scaled-up nozzles. A kind of hysteretic cavitation phenomenon was also observed in the experiment and then was analyzed in this paper. 相似文献
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柴油机孔式喷油嘴内空穴流动的模拟分析 总被引:5,自引:0,他引:5
利用混合多相流体模型加空穴模型的方法,模拟了柴油机孔式喷油嘴稳定喷射时嘴内的空穴流动现象,分析了空穴在喷油嘴内形成机理及其分布情况。基于这一模型进一步分析了喷射压力、背压和喷孔长径比、喷孔入口圆角比、非轴对称喷孔等几何结构参数对喷孔内空穴分布的影响。通过模拟计算可知,提高喷射压差和减小喷孔入口圆角半径都可以提高空穴强度,同时也发现提高喷孔长径比可以使空穴在喷孔出口截面上分布更为均匀。从燃油空穴雾化理论的角度出发,空穴强度的提高以及在出口截面上的均匀分布都有利于燃油的破碎雾化。 相似文献
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喷油器喷嘴内部的燃油的流动和空化直接影响燃油的喷射,又可造成喷嘴空蚀。基于不可压缩流体体积函数(VOF)多相流模型,模拟喷油器完整喷射周期内的燃油流动和空化特性,获得喷嘴空化形成及发展的关键区域和影响空化效应的关键结构参数,并分析其对流场及空化特性的影响规律。结果表明:较小针阀升程时,在针阀锥形表面台阶和喷孔下边缘位置处发生明显空化现象,当升程增加,空化集中分布在喷孔位置处,从倒圆处开始诱发,逐渐向下游延伸;针阀台阶夹角增大使得针阀表面台阶处和喷孔下缘的前部的局部空化增强,穴蚀更严重,且燃油流量减小,通过增大针阀座倒圆半径和喷孔直径锥度系数可有效地改善喷孔局部空化程度。 相似文献