The interaction of droplets with surfaces exhibiting different wettability, under various environmental conditions, plays a crucial role in a wide range of engineering applications. There are several methods to control the wettability of surfaces, such as plasma treatment, hydrophilic/hydrophobic coatings, and surface structuring. This study experimentally explores the dynamics of droplet impact on heated micro-textured surfaces, investigating different surface temperatures and Weber numbers.
Ten engineered surfaces, created in a clean room facility and featuring cylindrical micro-pillars textured on silicon wafers with varying configurations, are compared to both a flat surface and to each other. These configurations result in different values for the surface parameters r (roughness factor) and φ (solid packing fraction), which govern the impact regimes. Various combinations of these parameters were tested. Additionally, three droplet sizes are examined to analyze the influence of droplet physical dimensions and volume on impact morphology.
The interaction between surface temperatures and Weber numbers reveals multiple droplet impact regimes, which were classified in this study and detailed in phase maps. These regimes include spreading at low temperatures, coupling with film evaporation or nucleate boiling, while rebound and splashing with thermal atomization occur when the temperature exceeds the Leidenfrost point. Micro-structured surfaces significantly modify these regimes, particularly at higher temperatures, causing shifts across the examined Weber numbers and temperatures.
These findings highlight the pivotal role of surface microstructure in influencing droplet impact dynamics and heat transfer, offering valuable insights for optimizing surface designs in applications that require precise wettability and thermal management control.
The work is towards M.Sc. degree under the supervision of Asst. Prof. Alexandros Terzis, Department of Aerospace Engineering, Technion
Light refreshments will be served before the lecture
The interaction of droplets with surfaces exhibiting different wettability, under various environmental conditions, plays a crucial role in a wide range of engineering applications. There are several methods to control the wettability of surfaces, such as plasma treatment, hydrophilic/hydrophobic coatings, and surface structuring. This study experimentally explores the dynamics of droplet impact on heated micro-textured surfaces, investigating different surface temperatures and Weber numbers.
Ten engineered surfaces, created in a clean room facility and featuring cylindrical micro-pillars textured on silicon wafers with varying configurations, are compared to both a flat surface and to each other. These configurations result in different values for the surface parameters r (roughness factor) and φ (solid packing fraction), which govern the impact regimes. Various combinations of these parameters were tested. Additionally, three droplet sizes are examined to analyze the influence of droplet physical dimensions and volume on impact morphology.
The interaction between surface temperatures and Weber numbers reveals multiple droplet impact regimes, which were classified in this study and detailed in phase maps. These regimes include spreading at low temperatures, coupling with film evaporation or nucleate boiling, while rebound and splashing with thermal atomization occur when the temperature exceeds the Leidenfrost point. Micro-structured surfaces significantly modify these regimes, particularly at higher temperatures, causing shifts across the examined Weber numbers and temperatures.
These findings highlight the pivotal role of surface microstructure in influencing droplet impact dynamics and heat transfer, offering valuable insights for optimizing surface designs in applications that require precise wettability and thermal management control.
The work is towards M.Sc. degree under the supervision of Asst. Prof. Alexandros Terzis, Department of Aerospace Engineering, Technion
Light refreshments will be served before the lecture
