Jet Impingement on Complex Surfaces

Multiphase flows, such as liquid-gas flows, are omnipresent in power plants, pipelines and countless other engineering applications of great societal importance. How these flows interact with surfaces with varying natural or engineered texture is often a determining factor for process reliability and efficiency. However, the results of such multiphase flow and surface interactions are most often described based on fits to data that are only applicable to the specific application over a narrow range of conditions. Therefore, the principal aim of this project is to discover universal dependencies in such complex flows utilizing highly repeatable experiments studying liquid jet impingent on well-characterized textured engineered surfaces. The project also includes significant educational activity by providing undergraduate research opportunities and incorporates scalable outreach that will benefit the scientific and technical education of high school students as well. The engineering community’s fundamental understanding is very limited when it comes to the interaction of multiphase flows with complex surfaces, defined here as surfaces with (spatially or sample-to-sample) varying hydrophobicity and roughness. Such surfaces, when appropriately designed and fabricated, can also retain microscopic pockets of gas (called plastrons) whose state is a function of the flow they are exposed to, and which greatly impact the overall flow dynamics as shown by our preliminary study. This research builds upon the PIs’ prior published work on a complementary study and expands on the preliminary data yielded by the experimental jet impingement method we have developed. Guided by jet impingement and interfacial thermodynamic theories, these methods will be utilized to study boundary layer growth, wetting, and dewetting on random and structured surfaces with varying degrees of hydrophobicity. Elucidating the role of roughness, varying hydrophobicity and state of plastrons on the dynamics of impinging jets, and dewetting in case of gravity vector normal to surface outward, will contribute to the community's understanding of multiphase flow boundary layer flows – in addition to the enhanced understanding of the interaction of impinging jets on complex surfaces, which alone is an important topic of research. The fundamental understanding that the proposed research will contribute to can be readily utilized in numerous applications and have a broad societal impact in the near-term. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.