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High-speed visualization of rocket engine internal dynamics
A quartz class chamber is used to visualize the mutiphase combustion dynamics in a rocket engine operating under subcritical pressure. Film cooling fuel spreading on the internal wall is clearly visible.
Quantitative water-flow diagnostic
AIAA Journal of Propulsion and Power, "Direct Formulation of Bipropellant Thruster Performance for Quantitative Cold-Flow Diagnostic", Y.Oishi(M2)
Rocket engines and satellite thrusters produce spray by atomization to enhance evaporation and mixing for efficient combustion. Detailed spray characteristics are elucidated using high-speed visualization, multi-phase CFD, and theoretical modeling.
Performance of chemical propulsion systems, e.g. characteristic velocity. specific impulse and thrust, has become to be well predicted by newly developed theoretical model.
The figure shows a high-speed visualization of impinging atomization model for satellite thrusters.
Liquid sheet dynamics and entertainment on a wall driven by fast co-current gas stream with its thermal behavior
Physics of Fluids, "On the droplet entrainment from gas-sheared liquid film", I.Maeda(M2).
Liquid sheet sheared by an ambient gas flow is useful for cooling a combustion chamber wall. On the other hand, the film may cause icing or eroding machine parts. For utilizing properly liquid films, it is greatly desired to predict its flow characteristics including the wavy structure and the entrainment.
The movie shows dynamics of the liquid sheet with thickness of 1mm subjected to the air stream of 30 m/s.
Air-blast atomizer for jet engines, in which liquid sheet breaks up due to high-speed air streams, is a crucial component both for performance and environment.
The spray characteristics are clarified by high-speed visualization, newly developed mechanical patternator measurement, laser diagnostics, and multiphase CFD.
The picture shows a high-speed visualization of 2D liquid sheet.
Successive fragmentation cascade-Physics of beauty-
Physical Review Letters, "Direct Self-Sustained Fragmentation Cascade of Reactive Droplets", C.Inoue et al.
日本燃焼学会誌, "線香花火研究の最前線", 井上智博
A single droplet breaks up just once in general, at high-pressure diesel spray and by subjected to super-sonic flow. Contrary, we have discovered that an isolated droplet can successively fragment approximately 10 times through the self-similar cascade in the spark ramification process observed at Senko-hanabi (線香花火), which originated in Edo-period, 4 centuries ago.
The continuous internal gas production drives the bursting events of the droplets.
Science and Tech. Energetic Materials, "Analysis on unsteady thermal behavior of ground iron sparks", T.Kimura(M2)
In general, almost all of particles break up just once. However, carbon steel sparks are rare in which a single particle branches multiple times. The mechanism of multiple branches has not been known for more than 200 years, and we are trying to investigate it by high-speed measurement.
The figure is a carbon steel spark with a radius of 10 micrometers flying at 30 m/s.
Bouncing droplet on liquid film
Powder metallurgy and metal AM technology, utilizing for making aircraft parts such as fuel injection nozzle, need fine and spherical metal powders.
Water atomization is one of the most general methods to produce metal powders. We succeeded in the detailed high-speed observation and modeling of liquid metal fragmentation process.