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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

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)

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 for predicting rocket engine performance

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)

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.

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 metal sparks

金属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)

A single metal droplet of carbon steel branches multiple times, whose mechanism has not been known for more than 200 years. We are trying to elucidate it by high-speed measurement.

The figure is a carbon steel spark with a radius of 10 micrometers flying at 30 m/s.

Liquid metal fragmentation

液体金属の微粒化

Advanced Powder Tech., "Visualization and modeling for water atomization of low melting point alloy", W.Hikita(M2) & T.Ichimura(M1)

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.

Bouncing droplet on liquid film

液膜上における液滴の動的挙動解明

When a droplet is photographed with a high-speed camera, an interesting phenomenon occurs where the droplet rides nicely on the liquid film and bounces around.

The movie on the left is shot with a thin droplet thickness, and the movie on the right is shot with a thick droplet thickness, using water as the liquid. The difference between the thin and thick cases is the number of steps it takes for a droplet to be absorbed by the film, and the size of the second droplet that is formed once it is absorbed.

Real-time bubble/droplet detection

気泡や液滴のリアルタイム検知と計測

We have succeeded in real-time (in-situ) detection of bubbles and droplets over 1,000Hz for measuring the numbers, size, and velocity by using the latest high-speed streaming camera.

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)

微粒化, "二次元気流噴射弁における非定常噴霧構造の画像解析", 井上拓哉(M1)

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.