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The effect of nozzle geometry and injection pressure fluctuation on the in-nozzle flow and jet breakup based on the Multi-Fluid-LES model
Atomization and Sprays ( IF 1.2 ) Pub Date : 2020-09-01 , DOI: 10.1615/atomizspr.2020033622
Weilong Zhang , Hong Liu , Canxu Liu , Ming Jia , Xi Xi , Rong Xie

The three-dimensional in-nozzle flow of two single-hole injector nozzles are investigated based on the improved Multi-Fluid-Quasi-VOF solver coupled with the LES approach in the OpenFOAM framework. The cavitation model is also included to study the effect of the nozzle structure on the cavitation inside nozzle and primary breakup. The continuity equations and the momentum equations are reformulated by adding the mass and momentum source terms from cavitation, respectively. Furthermore, the influence of high frequency pressure fluctuations in the pressure chamber is analyzed. The improved model is validated by comparing the simulated mass flow rates, spray momentum fluxes, discharge coefficients and effective jet velocities with experimental values, and high consistency is obtained. In addition, the quality of the large eddy simulation is assessed by the proportion of the resolved kinetic energy. The results demonstrate that the jet breakup process of spray C nozzle is divided into two stages, i.e. the pre-supercavitation stage in which the jet breakup development is relatively slow and the post-supercavitation stage when the jet shatters violently. However, the jet breakup development of the spray D nozzle is much more gradual. The fluctuating injection pressure has a greater influence on the jet breakup of the spray C nozzle than that of the spray D nozzle due to the unstable cavitation.

中文翻译:

基于Multi-Fluid-LES模型的喷嘴几何形状和喷射压力波动对喷嘴内流动和射流破裂的影响

在OpenFOAM框架中,基于改进的Multi-Fluid-Quasi-VOF解算器和LES方法,研究了两个单孔喷嘴的三维喷嘴内流动。还包括空化模型,以研究喷嘴结构对喷嘴内部空化和一次破碎的影响。通过分别添加空化的质量和动量源项,可以重新构造连续性方程和动量方程。此外,分析了压力室中高频压力波动的影响。通过将模拟质量流量,喷雾动量通量,排放系数和有效射流速度与实验值进行比较,验证了改进后的模型的正确性。此外,大涡模拟的质量通过解析动能的比例进行评估。结果表明,喷雾C喷嘴的射流破碎过程分为两个阶段,即超空化前阶段和射流剧烈破碎后的超空化阶段。然而,喷雾D喷嘴的射流破裂发展是渐进的。由于不稳定的气穴作用,波动的喷射压力对喷雾C喷嘴的射流破裂的影响比对喷雾D喷嘴的射流破裂的影响大。在超空化之前阶段,射流破裂发展相对较慢;在超空化阶段之后,射流剧烈破碎。然而,喷雾D喷嘴的射流破裂发展是渐进的。由于不稳定的气穴作用,波动的喷射压力对喷雾C喷嘴的射流破裂的影响比对喷雾D喷嘴的射流破裂的影响大。在超空化之前阶段,射流破裂发展相对较慢;在超空化阶段之后,射流剧烈破碎。然而,喷雾D喷嘴的射流破裂发展是渐进的。由于不稳定的气穴作用,波动的喷射压力对喷雾C喷嘴的射流破裂的影响比对喷雾D喷嘴的射流破裂的影响大。
更新日期:2020-09-10
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