Maria Teresa Scelzo
PhD Candidate
Environmental and Applied Fluid Dynamics Department
von Karman Institute for Fluid Dynamics
Waterloosesteenweg 72
1640 Sint-Genesius-Rode
Phone: +32 2 359 96 11
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FRIA Grant 2018 (1st year)
PhD Subject: Characterisation of Cryogenic Slush for Future Launcher Engines
Liquid hydrogen is widely used as fuel in rocket engines due to the high specific impulse provided. However, several problems are related to this choice, such us low density, temperature stratification and short holding time. Moreover, strong sloshing can occur due to the liquid state. A promising way to reduce these problems is to use slush, that is a solid-liquid mixture with 15% higher density and 18% higher specific enthalpy. The employment of this form of propellant results in promising new concept rocket engines. However, the presence of solid particle in the liquid suspension changes the flow properties: the rheological behaviour becomes non-Newtonian for high particle concentration and, due to the heat transfer, the solid fraction may partially melt changing slush features. Hence, the standard correlations for the liquid flow in tubes are no longer valid. An observed phenomenon of drag reduction appears to be interesting for improving system efficiency, but it has never been completely understood. Therefore, the optimization of the slush transport through circular pipelines and narrowing, requires the measurement of the slush physical features, along with their modelling.
The goal of this research project is to provide a complete understanding of the slush behaviour at different flow conditions such as velocity, mass fraction concentration and particle distribution. Due to the high risks and extremely high costs involved in using hydrogen, the research will be carried out for slush nitrogen. An intense experimental campaign will furnish a complete database concerning pressure drops, heat transfer and phase change phenomena. This database will be used to design improved engineering correlations as well as revised models for Eulerian-Eulerian numerical approaches available in existing softwares, to be used in the design of slush transport and storage systems.