The dynamic behaviors of supercooled large water droplets(SLDs)in airflow involving deformation,breakup,and splash affect the local water collection coefficient,leading to an increase in the complexity of aircraft ici...The dynamic behaviors of supercooled large water droplets(SLDs)in airflow involving deformation,breakup,and splash affect the local water collection coefficient,leading to an increase in the complexity of aircraft icing.A parametric study on the influence of deformed water droplets in shear flow is investigated experimentally and numerically.A horizontal refrigerated wind tunnel is used to create the background shear airflow.A high-speed camera records the evolution of cross-stream/streamwise diameters and the breakup process.The level set method is employed to capture the deformation of micrometer-sized supercooled water droplets in continuous airflow.The deformation modes are categorized into five regimes:stabilization,vibration,transition,bag breakup,and bag-stamen breakup.A dimensionless deformation factor L is defined to describe the droplet deformation,which increases with airflow speed,droplet volume,and temperature.Applying the scaling expression Oh~(4.39)We~(0.85),a normalized acceleration model of water droplets in shear airflow is established.Based on the experimental results,a drag coefficient model for disc-shaped droplets within the transient Reynolds number range of 420-10000 is obtained.As the initial Weber number exceeds 9.5 and the maximum deformation factor exceeds 3.5,the droplet enters the breakup regime.Furthermore,bag-stamen breakup occurs when the initial Weber number exceeds 17.5.展开更多
为提升重庆区域航空气象保障能力,降低积冰对飞行安全的影响,基于2021~2023年重庆江北机场航空器空中报告数据,系统分析了该区域飞机积冰的时间、高度及空间分布特征,并探讨了积冰预报方法在区域航空气象服务中的应用。结果表明:重庆区...为提升重庆区域航空气象保障能力,降低积冰对飞行安全的影响,基于2021~2023年重庆江北机场航空器空中报告数据,系统分析了该区域飞机积冰的时间、高度及空间分布特征,并探讨了积冰预报方法在区域航空气象服务中的应用。结果表明:重庆区域3年共记录积冰69次,其中严重积冰34次、中度33次、轻度2次;积冰季节性特征显著,冬季占比66%,1~2月为高发期;高度集中在2~4 km (占比64.2%),且冬季高度最低、夏季最高;空间分布集中于本场(36%)、东1区(25%)和北1区(20%),北1区严重积冰占比达91%。基于IC指数法、VV积冰指数等构建的航空气象综合服务平台,实现了积冰预报的可视化与实时验证,为区域飞行安全提供了有效支撑。未来需结合航路流量信息进一步优化预报精度,提升预警精细化水平。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12227802)。
文摘The dynamic behaviors of supercooled large water droplets(SLDs)in airflow involving deformation,breakup,and splash affect the local water collection coefficient,leading to an increase in the complexity of aircraft icing.A parametric study on the influence of deformed water droplets in shear flow is investigated experimentally and numerically.A horizontal refrigerated wind tunnel is used to create the background shear airflow.A high-speed camera records the evolution of cross-stream/streamwise diameters and the breakup process.The level set method is employed to capture the deformation of micrometer-sized supercooled water droplets in continuous airflow.The deformation modes are categorized into five regimes:stabilization,vibration,transition,bag breakup,and bag-stamen breakup.A dimensionless deformation factor L is defined to describe the droplet deformation,which increases with airflow speed,droplet volume,and temperature.Applying the scaling expression Oh~(4.39)We~(0.85),a normalized acceleration model of water droplets in shear airflow is established.Based on the experimental results,a drag coefficient model for disc-shaped droplets within the transient Reynolds number range of 420-10000 is obtained.As the initial Weber number exceeds 9.5 and the maximum deformation factor exceeds 3.5,the droplet enters the breakup regime.Furthermore,bag-stamen breakup occurs when the initial Weber number exceeds 17.5.
文摘为提升重庆区域航空气象保障能力,降低积冰对飞行安全的影响,基于2021~2023年重庆江北机场航空器空中报告数据,系统分析了该区域飞机积冰的时间、高度及空间分布特征,并探讨了积冰预报方法在区域航空气象服务中的应用。结果表明:重庆区域3年共记录积冰69次,其中严重积冰34次、中度33次、轻度2次;积冰季节性特征显著,冬季占比66%,1~2月为高发期;高度集中在2~4 km (占比64.2%),且冬季高度最低、夏季最高;空间分布集中于本场(36%)、东1区(25%)和北1区(20%),北1区严重积冰占比达91%。基于IC指数法、VV积冰指数等构建的航空气象综合服务平台,实现了积冰预报的可视化与实时验证,为区域飞行安全提供了有效支撑。未来需结合航路流量信息进一步优化预报精度,提升预警精细化水平。
