Measurement technology of the impact of alumina liquid particles on a hot surface

The aim of this study, carried out in the frame of the ASSM (Aerodynamics of Segmented Solid Motors) research program, is a better understanding of the phenomena that govern the interactions between liquid alumina particles and a hot surface or liquid alumina film. To achieve it, a complex experimental device has been designed and built. In a controlled argon atmosphere chamber are set two plasma torches and a reclining substrate. This set-up allows the use of carbon-carbon substrates. The first plasma torch produces molten alumina particles, and the second one heats the substrate up to 2300 K. An optical diagnostic characterizes the in-flight parameters of a single particle : its size and velocity by PDA (Particle Doppler Anemometry) and its temperature by two-color fast (100 ns) pyrometry. An imaging technique monitors the impact mode: splashing, deposition or rebound. For the latter the rebounding angle and velocity can be measured. A laser beam is used for visualization of trajectories in a narrow wavelength band-pass. For each droplet, its size, velocity and temperature are measured and impact is observed. The goal is to investigate how the impact mode is influenced by these parameters.