Diagnostics for Entrainment Characterization in Liquefying Fuel Formulations

This paper focuses on an experimental investigation of the entrainment of melted fuel droplets in liquefying fuel formulations. The work considers compositions featuring different viscosities, and is divided in two parts. In the first one, the entrainment of melted fuels is investigated by a dedicated setup enabling the visualization of the oxidizer stream/melt surface interaction under cold-flow conditions (without combustion) at 0.1 MPa. The melted liquid surface behavior is recorded by a high-speed camera. The captured images are processed to have a better insight of the droplet formation mechanism, and to measure their size distribution. In the second part of the work, the fuels are burnt in a lab-scale motor for an evaluation of their regression rate. Achieved results show that the regression rate enhancement is stronger for the fuel formulation with the higher number of entrained droplets, while the sizes of the same show no marked differences between the tested materials.