Through CAMEE, Combs has received a grant from the Defense University Research Instrumentation Program, under the U.S. This type of camera is also being used to help UTSA’s softball team and could be available for other unique types of applications on campus. Combs will primarily use the new camera to support research in his high-speed aerodynamics lab at UTSA. P.The camera is also being used to help UTSA’s softball team and could be available for other research on campus.ĭECEMWhat can you do with a video camera that captures up to 2 million frames per second? Christopher Combs, the Dee Howard Endowed Assistant Professor in Aerodynamics in the Department of Mechanical Engineering and core faculty member of the Center of Advanced Measurements in Extreme Environments, said there are many possibilities. Metastable Leidenfrost States (NASA Technical Note D3226, 1966)Ĭarey, V. Effect of an electric field on a Leidenfrost droplet. On the existence of two “transition” boiling cure. Maximum and minimum values of heat Q transmitted from metal to boiling water under atmospheric pressure. Subcooled film boiling heat transfer from spheres. Underwater restoration and retention of gases on superhydrophobic surfaces for drag reduction. Underwater breathing: the mechanics of plastron respiration.
Remarkably simple fabrication of superhydrophobic surfaces using electroless galvanic deposition. On the modeling of hydrophobic contact angles on rough surfaces.
Immersed superhydrophobic surfaces: gas exchange, slip and drag reduction properties. Friction drag reduction of external flows with bubble and gas injection. Boiling on free-falling spheres: drag and heat transfer coefficients. On the effect of surface roughness height, wettability, and nanoporosity on Leidenfrost phenomena. Water droplet motion control on superhydrophobic surfaces: exploiting the Wenzel-to-Cassie transition. Macroscopically flat and smooth superhydrophobic surfaces: heating induced wetting transitions up to the Leidenfrost temperature. Nanowires for enhanced boiling heat transfer. et al.) 300–304 (Engineering Conferences International, 2005)Ĭhen, R. Enhanced, Compact and Ultra-compact Heat Exchangers: Science, Engineering and Technology (eds Shah, R. Effect of surface wettability on active nucleation site density during pool boiling of water on a vertical surface. Supernucleating surfaces for nucleate boiling and dropwise condensation heat transfer. Candle soot as a template for a transparent robust superamphiphobic coating. Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity. Design of ice-free nanostructured surfaces based on repulsion of impacting water droplets. Drag reduction by Leidenfrost vapor layers. The Leidenfrost point: experimental study and assessment of existing models. On the fixation of water in diverse fire. De aquae communis nonnullis qualitatibus tractatus (Duisburg, 1756) transl. This concept can potentially be applied to control other phase transitions, such as ice or frost formation 7, 8, 9, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating 10. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid–gas phase transition at hot surfaces.
In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. The presence of these vapour films can also reduce liquid–solid drag 4, 5, 6. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants 3.
In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling 2. In 1756, Leidenfrost 1 observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film.