Abstract A comprehensive three-dimensional model of droplet-gas flow was presented to study the evolution of spray in the effervescent atomization spray with an impinging plate. For gas phase, the N-S equation with t...Abstract A comprehensive three-dimensional model of droplet-gas flow was presented to study the evolution of spray in the effervescent atomization spray with an impinging plate. For gas phase, the N-S equation with the κ-ε turbulence model was solved, considering two-way coupling interaction between droplets and gas phase. Dispersed droplet phase is modeled as Lagrangian entities, accounting for the physics of droplet generation from primary and secondary breakup, droplet collision and coalescence, droplet momentum and heat transfer. The mean size and sta- tistical distribution of atomized droplets at various nozzle-to-plate distances were calculated. Some simulation resuits were compared well with experimental data. The results show that the existence of the impinging plate has a pronounced influence on the droplet mean size, size distribution and the droplet spatial distribution. The air-to-liquid ratio has obvious effects on the droplet size and distribution.展开更多
Computational fluid dynamics is an efficient numerical approach for spray atomization study, but it is challenging to accurately capture the gas-liquid interface. In this work, an accurate conservative level set metho...Computational fluid dynamics is an efficient numerical approach for spray atomization study, but it is challenging to accurately capture the gas-liquid interface. In this work, an accurate conservative level set method is intro- duced to accurately track the gas-liquid interfaces in liquid atomization. To validate the capability of this method, binary drop collision and drop impacting on liquid film are investigated. The results are in good agreement with experiment observations. In addition, primary atomization （swirling sheet atomization） is studied using this method. To the swirling sheet atomization, it is found that Rayleigh-Taylor instability in the azimuthal direction causes the primary breakup of liquid sheet and complex vortex structures are clustered around the rim of the liq- uid sheet. The effects of central gas velocity and liquid-gas density ratio on atomization are also investigated. This work lays a solid foundation for further studvin~ the mechanism of s^rav atomization.展开更多
Diesel spray is injected at high pressure. So, upper stream region of spray is high Weber number condition. However, even if the fuel is injected at high pressure, the downstream region of spray is corresponding to re...Diesel spray is injected at high pressure. So, upper stream region of spray is high Weber number condition. However, even if the fuel is injected at high pressure, the downstream region of spray is corresponding to relatively low Weber number condition. Thus, KH （Kelvin-Helmholtz） model modeled for high Weber number conditions and MTAB （modified Taylor analogy breakup） model are used for primary and secondary breakup processes respectively. This study is focused on the development of new hybrid breakup model The calculations are performed by LES （large eddy simulation） incorporated into KIVA code. LES of non-evaporating diesel spray are performed using KH ＆ RT （Rayleigh-Taylor） model, MTAB model and KH-MTAB model. Then, LES with these models were compared with experimental results. As the result, the availability of KH-MTAB model is showed. It is found that KH-MTAB is good agreement with experimental results of penetration and SMD （Sauter mean diameter） in relatively low density conditions.展开更多
基金Supported by the Major Program of the National Natural Science Foundation of China （10632070）
文摘Abstract A comprehensive three-dimensional model of droplet-gas flow was presented to study the evolution of spray in the effervescent atomization spray with an impinging plate. For gas phase, the N-S equation with the κ-ε turbulence model was solved, considering two-way coupling interaction between droplets and gas phase. Dispersed droplet phase is modeled as Lagrangian entities, accounting for the physics of droplet generation from primary and secondary breakup, droplet collision and coalescence, droplet momentum and heat transfer. The mean size and sta- tistical distribution of atomized droplets at various nozzle-to-plate distances were calculated. Some simulation resuits were compared well with experimental data. The results show that the existence of the impinging plate has a pronounced influence on the droplet mean size, size distribution and the droplet spatial distribution. The air-to-liquid ratio has obvious effects on the droplet size and distribution.
基金the National Natural Science Foundation of China(51176170,51276163)the Zhejiang Provincial Natural Science Foundation for Distinguished Young Scholars(LR12E06001)supported by the Fundamental Research Funds for the Central Universities
文摘Computational fluid dynamics is an efficient numerical approach for spray atomization study, but it is challenging to accurately capture the gas-liquid interface. In this work, an accurate conservative level set method is intro- duced to accurately track the gas-liquid interfaces in liquid atomization. To validate the capability of this method, binary drop collision and drop impacting on liquid film are investigated. The results are in good agreement with experiment observations. In addition, primary atomization （swirling sheet atomization） is studied using this method. To the swirling sheet atomization, it is found that Rayleigh-Taylor instability in the azimuthal direction causes the primary breakup of liquid sheet and complex vortex structures are clustered around the rim of the liq- uid sheet. The effects of central gas velocity and liquid-gas density ratio on atomization are also investigated. This work lays a solid foundation for further studvin~ the mechanism of s^rav atomization.
文摘Diesel spray is injected at high pressure. So, upper stream region of spray is high Weber number condition. However, even if the fuel is injected at high pressure, the downstream region of spray is corresponding to relatively low Weber number condition. Thus, KH （Kelvin-Helmholtz） model modeled for high Weber number conditions and MTAB （modified Taylor analogy breakup） model are used for primary and secondary breakup processes respectively. This study is focused on the development of new hybrid breakup model The calculations are performed by LES （large eddy simulation） incorporated into KIVA code. LES of non-evaporating diesel spray are performed using KH ＆ RT （Rayleigh-Taylor） model, MTAB model and KH-MTAB model. Then, LES with these models were compared with experimental results. As the result, the availability of KH-MTAB model is showed. It is found that KH-MTAB is good agreement with experimental results of penetration and SMD （Sauter mean diameter） in relatively low density conditions.
