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AIAA Journal of Propulsion and Power, "Visualization of Pulse Firing Mode in Hypergolic Bipropellant Thruster", G.Fujii(D1)AIAA Journal of Propulsion and Power, "Visualization of coolant liquid film dynamics in hypergolic bipropellant thruster", G.Fujii(D2)

High-speed visualization of rocket engine internal dynamics

ロケットエンジン内部流の高速度可視化計測

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

水流し試験によるロケットエンジン性能の定量的予測


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

高速気流に駆動される壁面上液膜の動力学と伝熱特性


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.

Airblast sheet fragmentation in jet engines

ジェットエンジン燃料液膜の微粒化


Int. J. Multiphase Flow, "Measurement and modeling of planar airblast spray flux distributions", H.Yoshida(M2)

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-

液滴の連鎖的な分裂現象の発見と解明-線香花火の科学-


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.

Successive branching of carbon steel sparks

炭素鋼火花の連鎖分裂機構の解明


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

液膜上における液滴の動的挙動解明

液滴をハイスピードカメラで撮影すると液滴が液膜上に綺麗に乗ってぴょんぴょん跳ねる面白い現象が起こる。左の動画は液膜厚さが薄い場合、右の動画は厚い場合で撮影しており、液体には水を使用しています。薄い場合と厚い場合の違いとして、液滴が液膜に吸収されるまでにかかるステップ回数、一度吸収されて2番目にできる液滴の大きさが異なっています。


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.