Liquid breakup in fuel spray and atomization significantly affects the consequent mixture formation, combustion behavior, and emission formation processes in a direct injection diesel engine. In this paper, different ...Liquid breakup in fuel spray and atomization significantly affects the consequent mixture formation, combustion behavior, and emission formation processes in a direct injection diesel engine. In this paper, different models for liquid breakup processes in high-pressure dense diesel sprays and its impact on multi-dimensional diesel engine simulation have been evaluated against experi- mental observations, along with the influence of the liquid breakup models and the sensitivity of model parameters on diesel sprays and diesel engine simulations. It is found that the modified Kelvin-Helmholtz （KH）-Rayleigh-Taylor （RT） breakup model gives the most reasonable predicted results in both engine simulation and high-pressure diesel spray simulation. For the standard KH-RT model, the model constant Cbl for the breakup length has a significant effect on the predictability of the model, and a fixed value of the constant Cbl cannot provide a satisfactory result for different operation conditions. The Taylor-analogy- breakup （TAB） based models and the RT model do not provide reasonable predictions for the characteristics of high-pressure sprays and simulated engine performance and emissions.展开更多
The experimental elastic cross section data of the projectile11 Be on target12 C at 49.3 Me V/nucleon energy is analysed. The calculations for the elastic scattering are performed by the phenomenological optical model...The experimental elastic cross section data of the projectile11 Be on target12 C at 49.3 Me V/nucleon energy is analysed. The calculations for the elastic scattering are performed by the phenomenological optical model. The different optical potentials to include breakup effects into the calculations, which are neutron+12C, neutron+10Be and10Be+12C, are described with the aid of the global potentials for neutron interactions and fitted to experimental data for the core and target interaction. Also, the first analysis of the optical model for10 Be on target12 C at 39.1 Me V is done for building the interaction potential of the core and the target for11 Be. For investigating the effects of the spectroscopic factors, obtained factors from the direct capture process using the nuclear level density are compared with the previous cross section and spectroscopic factor results. Obtained results for the elastic cross section reproduce the experimental data very well and show the requirement of including spectroscopic properties such as, spectroscopic factors and density of the excited states, to explain this elastic cross section data.展开更多
The relationship of N2O distributions with the Arctic vortex breakup is first analyzed with a probability distribution function （PDF） analysis. The N2O concentration shows different distributions between the early a...The relationship of N2O distributions with the Arctic vortex breakup is first analyzed with a probability distribution function （PDF） analysis. The N2O concentration shows different distributions between the early and late vortex breakup years. In the early breakup years, the N2O concentration shows low values and large dispersions after the vortex breakup, which is related to the inhomogeneity in the vertical advection in the middle and high latitude lower stratosphere. The horizontal diffusion coefficient （Kyy） shows a larger value accordingly. In the late breakup years, the N2O concentration shows high values and more uniform distributions than in the early years after the vortex breakup, with a smaller vertical advection and Kyy after the vortex breakup. It is found that the N2O distributions are largely affected by the Arctic vortex breakup time but the dynamically defined vortex breakup time is not the only factor.展开更多
目前的民机结冰适航规范中,大粒径过冷水滴(supercooled large droplet,SLD)环境尚未得到规定,是一个重大的飞行安全隐患。由于SLD的粒径较大(大于50μm),在研究其结冰时需要考虑水滴动力学过程。针对SLD成冰模拟中破碎模型的不足,根据...目前的民机结冰适航规范中,大粒径过冷水滴(supercooled large droplet,SLD)环境尚未得到规定,是一个重大的飞行安全隐患。由于SLD的粒径较大(大于50μm),在研究其结冰时需要考虑水滴动力学过程。针对SLD成冰模拟中破碎模型的不足,根据对破碎机理的认识提出了多因素破碎(multifactor-effected breakup,MEB)判定模型,并结合积冰算法对SLD环境中的结冰进行了模拟,验证了模型的有效性,证明其能提高对SLD结冰的模拟能力。从翼面收集率及冰型生长两方面对SLD的结冰过程和水滴动力学过程产生的效应进行了分析。展开更多
文摘Liquid breakup in fuel spray and atomization significantly affects the consequent mixture formation, combustion behavior, and emission formation processes in a direct injection diesel engine. In this paper, different models for liquid breakup processes in high-pressure dense diesel sprays and its impact on multi-dimensional diesel engine simulation have been evaluated against experi- mental observations, along with the influence of the liquid breakup models and the sensitivity of model parameters on diesel sprays and diesel engine simulations. It is found that the modified Kelvin-Helmholtz （KH）-Rayleigh-Taylor （RT） breakup model gives the most reasonable predicted results in both engine simulation and high-pressure diesel spray simulation. For the standard KH-RT model, the model constant Cbl for the breakup length has a significant effect on the predictability of the model, and a fixed value of the constant Cbl cannot provide a satisfactory result for different operation conditions. The Taylor-analogy- breakup （TAB） based models and the RT model do not provide reasonable predictions for the characteristics of high-pressure sprays and simulated engine performance and emissions.
基金Supported by the Turkish Science and Research Council(TBTAK)(No.112T566)
文摘The experimental elastic cross section data of the projectile11 Be on target12 C at 49.3 Me V/nucleon energy is analysed. The calculations for the elastic scattering are performed by the phenomenological optical model. The different optical potentials to include breakup effects into the calculations, which are neutron+12C, neutron+10Be and10Be+12C, are described with the aid of the global potentials for neutron interactions and fitted to experimental data for the core and target interaction. Also, the first analysis of the optical model for10 Be on target12 C at 39.1 Me V is done for building the interaction potential of the core and the target for11 Be. For investigating the effects of the spectroscopic factors, obtained factors from the direct capture process using the nuclear level density are compared with the previous cross section and spectroscopic factor results. Obtained results for the elastic cross section reproduce the experimental data very well and show the requirement of including spectroscopic properties such as, spectroscopic factors and density of the excited states, to explain this elastic cross section data.
文摘The relationship of N2O distributions with the Arctic vortex breakup is first analyzed with a probability distribution function （PDF） analysis. The N2O concentration shows different distributions between the early and late vortex breakup years. In the early breakup years, the N2O concentration shows low values and large dispersions after the vortex breakup, which is related to the inhomogeneity in the vertical advection in the middle and high latitude lower stratosphere. The horizontal diffusion coefficient （Kyy） shows a larger value accordingly. In the late breakup years, the N2O concentration shows high values and more uniform distributions than in the early years after the vortex breakup, with a smaller vertical advection and Kyy after the vortex breakup. It is found that the N2O distributions are largely affected by the Arctic vortex breakup time but the dynamically defined vortex breakup time is not the only factor.
文摘目前的民机结冰适航规范中,大粒径过冷水滴(supercooled large droplet,SLD)环境尚未得到规定,是一个重大的飞行安全隐患。由于SLD的粒径较大(大于50μm),在研究其结冰时需要考虑水滴动力学过程。针对SLD成冰模拟中破碎模型的不足,根据对破碎机理的认识提出了多因素破碎(multifactor-effected breakup,MEB)判定模型,并结合积冰算法对SLD环境中的结冰进行了模拟,验证了模型的有效性,证明其能提高对SLD结冰的模拟能力。从翼面收集率及冰型生长两方面对SLD的结冰过程和水滴动力学过程产生的效应进行了分析。
