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| 变温液滴撞击超疏水壁面动态行为研究 |
| Study on the Dynamic Behavior of Temperature-varying Glycerol Droplets Impacting Superhydrophobic Surfaces |
| 投稿时间：2026-03-10 修订日期：2026-04-07 |
| DOI： |
| 中文关键词: 液滴撞击 超疏水表面 变物性 物性瞬变 破碎阈值 |
| 英文关键词: droplet impact superhydrophobic surface non-isothermal temperature-dependent viscosity breakup threshold. |
| 基金项目:重庆市教委科学技术研究项目 (No.KJQN202301531)；重庆市科技局联合创新基金 (CSTB2022NSCQ-LZX0071)；重庆市自然科学基金面上项目（CSTB2023NSCQ-MSX0718）；重庆科技大学研究生创新项目（YKJCX2420334） |
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| 中文摘要: |
| 在热喷涂加工及冶金熔渣余热回收等工业领域，普遍涉及高温液滴撞击低温壁面的物理过程。在此过程中，强烈的瞬态换热会导致液滴动力黏度μ与表面张力σ发生剧烈波动，进而深刻影响液滴的铺展与回缩行为。然而，目前关于此类非等温撞击过程中物性瞬变对动力学调控机制的研究仍不充分。
基于甘油水溶液物性对于温度的高敏感性，本文以60%甘油水溶液为高粘性代表工质，在壁面恒温25℃的条件下，系统开展了变温液滴撞击超疏水壁面的可视化试验，旨在揭示非等温撞击过程中的通用动力学演化机理。通过控制液滴初温（40-70℃）、粒径（2.1mm及2.8mm）和撞击速度（0.99-2.8m/s），利用2000fps高速摄像机捕捉其演化全过程。液滴初温从40℃升至70℃使其动力黏度降低56.9%。低黏度特性有效削减了黏性耗散，使最大铺展系数βmax随温度升高而增大。当韦伯数We<115时液滴保持完整。随We增加，高温显著诱导破碎临界阈值左移，使液滴在较低速度下更易发生回缩破碎或冠状破碎。撞击初期由惯性力绝对主导；铺展中后期及回缩阶段则受温变黏度的强烈调控。本研究揭示了热-力耦合下的液滴失稳路径，可为优化热喷涂涂层均匀性及提升熔渣换热效率提供理论指导。 |
| 英文摘要: |
| In industrial fields such as thermal spraying and waste heat recovery of metallurgical slag, the physical process of high-temperature droplets impacting low-temperature walls is ubiquitous. During this process, intense transient heat transfer leads to significant fluctuations in dynamic viscosity (μ) and surface tension (σ), which profoundly affects the spreading and retraction behavior of the droplets. However, research on the regulatory mechanisms of dynamic behavior by transient physical properties during such non-isothermal impact remains insufficient.
Based on the high sensitivity of the physical properties of glycerol-water solutions to temperature, a 60% glycerol-water solution was selected as a representative high-viscosity working fluid. Under a constant wall temperature of 25°C, visualization experiments of variable-temperature droplets impacting a superhydrophobic surface were systematically performed, aiming to reveal the general dynamic evolution mechanisms during the non-isothermal impact process. By controlling initial droplet temperatures (40-70℃), diameters (2.1mm and 2.8mm, and impact velocities (0.99-2.8m/s), the entire evolution process was captured by a high-speed camera at 2000fps. Results show that increasing the initial temperature from 40℃ to 70℃ reduces the dynamic viscosity by 56.9%. This low-viscosity characteristic effectively diminishes viscous dissipation, causing the maximum spreading factor (βmax) to increase with temperature. Droplets remain intact when the Weber number We < 115. As We increases, high temperatures significantly induce a leftward shift in the breakup threshold, making droplets more prone to retraction breakup or crown splashing at lower velocities. The early stage of impact is dominated by inertial forces, whereas the late spreading and retraction stages are strongly regulated by temperature-dependent viscosity. This study reveals the droplet instability pathways under thermal-mechanical coupling, providing theoretical guidance for optimizing coating uniformity in thermal spraying and improving slag heat transfer efficiency. |
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