AI 中文总结
研究正十六烷单液滴在300 - 500°C、韦伯数5.77 - 208.61的加热不锈钢壁面上的铺展与破碎，通过高速背光图像实验并结合层流 - 边缘模型分析，结果表明模型推断的层流厚度能补充传统状态图，为破碎时间提供局部状态信息。
AI 中文摘要
热壁燃料液滴撞击影响柴油相关喷雾壁系统中的液体再分布、二次液滴形成和液滴蒸发。本研究调查了作为单组分柴油替代物的正十六烷单液滴在300 - 500°C的加热不锈钢壁面上，韦伯数（We）范围为5.77 - 208.61时的铺展和破碎情况。实验中记录高速背光图像以分类沉积、反弹、喷射、破碎和飞溅状态，并测量铺展因子历史。将测量的铺展历史与层流 - 边缘模型比较，评估其在液滴破碎前的预测能力并推断实验观察到的破碎瞬间的层流状态。300°C的情况在当前撞击条件下未进入莱顿弗罗斯特状态，作为非莱顿弗罗斯特参考，与模型预测有偏差。对于350 - 500°C的莱顿弗罗斯特情况，模型捕捉到破碎前的铺展轨迹。壁温对早期铺展阶段影响有限，但对层流变薄后的后期破碎时间影响更大，尤其是在中等韦伯数区域。在高韦伯数下，破碎越来越受惯性主导。在实验观察到的破碎瞬间模型推断的层流厚度主要集中在初始液滴直径的0.010至0.017之间。这些结果表明，模型推断的层流厚度可为热壁燃料液滴撞击模型中的破碎时间提供局部状态信息，从而补充传统的基于韦伯数和温度的状态图。
英文摘要
Hot-wall fuel-droplet impingement affects liquid redistribution, secondary droplet formation, and droplet evaporation in diesel-relevant spray-wall systems. This study investigates the spreading and breakup of single n-hexadecane droplets, used as a single-component diesel surrogate, on a heated stainless-steel wall at 300-500 °C over a Weber number (We) range of 5.77-208.61. High-speed backlit images were recorded during experiments and used to classify deposition, rebound, ejection, fragmentation, and splashing regimes, and to measure spreading-factor histories. The measured spreading histories were compared with a lamella-rim model to evaluate its predictive capability before droplet breakup and to infer the lamella state at experimentally observed breakup instants. The 300 °C cases did not enter the Leidenfrost regime under the present impact conditions and therefore serve as a non-Leidenfrost reference, deviating from the model predictions. For Leidenfrost cases at 350-500 °C, the model captures the pre-breakup spreading trajectory, including higher-We cases that later undergo breakup. Wall temperature has a limited influence on the early spreading stage but more strongly affects later breakup timing after lamella thinning, especially in the intermediate-We regime. At high We, breakup becomes increasingly inertia-dominated. Model-inferred lamella thicknesses evaluated at experimentally observed breakup instants are mainly concentrated between 0.010 and 0.017 of the initial droplet diameter. These results suggest that model-inferred lamella thickness can complement conventional Weber-number and temperature-based regime maps by providing local-state information for breakup timing in hot-wall fuel-droplet impingement models.
