APL推進研

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Real-time imaging of carbon dioxide emissions form aircraft

航空機排出CO2の直接イメージング

Environmental Advances, "On-Site Direct Imaging of Carbon Dioxide Emissions from Aircraft during Landing and Take-Off Cycle"https://doi.org/10.1016/j.envadv.2023.100432

On-site direct and selective imaging of CO2 emissions from aircraft was successfully performed at Fukuoka International Airport in Japan. We employed the latest infrared camera with a remarkably narrow bandpass filter ranging from 4.2 to 4.4 micro-meter, corresponding to the low-transmittance wavelength of CO2.

最新の航空機ジェットエンジンから排気される二酸化炭素(CO2)を，直接かつ選択的に動画として撮影することに成功しました．排出源を含むCO2のリアルタイムモニタリングへの応用が期待されます．実験は，福岡国際空港にて実施しました．

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.

Rocket engine performance prediction

水流し試験によるロケットエンジン性能の定量的予測

We successfully predict the performance of chemical propulsion systems, e.g. characteristic velocity. specific impulse and thrust by the newly developed theoretical model. The figure shows unlike impinging atomization.

Liquid sheet dynamics and phase change on a wall driven by fast gas stream

高速気流に駆動される壁面上液膜の動力学と伝熱特性

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.

Optimum design of liquid rocket engine to realize the maximum Isp and the best film cooling

最高性能と最高耐熱性を両立する最適ロケットエンジン設計法

AIAA Journal of Propulsion and Power, "Optimal Liquid Engine Architecture by Performance-Cooling Tradeoff Analysis", S.Tauchi(M2)

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-

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

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.

Water atomization of liquid metal

液体金属の水アトマイズ

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.

Gas atomization of liquid metal

超音速気流による液体金属アトマイズ

Materials & Design, "Direct imaging of gas atomization process accompanying surface oxidation of tin droplets", T.Tanimoto(M1), N.Uchida(M2)

Viscous-capillary fragmentation of liquid metal thread accompanying interfacial molecular diffusion

粘性と表面張力が連成した液糸分裂

Int. J. Heat and Mass Transfer, "Viscous-capillary thinning of molten metal ligament stimulated by surface oxidation", M.Ren(D3), H.Yasuhara(M2)

The water ligament (left) breaks into several spherical drops by surface tension. Contrary, the tin ligament (right) fragments affected by surface oxidation, leading to the irregular topologies of daughter particles. Unsteady temperature measurement (top) reveals the typical breakup process has no effect by solidification.

Annular liquid film fragmentation by fully-developed turbulent gas flow

発達した乱流気流に駆動された液膜の微粒化

ASME J. Eng. Gas Turbines and Power, "Relationship between wavy liquid film dynamics and droplet formation from trailing edge", Y.Kamada (D1)

The liquid film on the inner pipe wall is subjected to the high-speed central air flow. When there is no gas flow (left image), we confirm the smooth film flow, which gathers into a single ligament, evidencing the uniform thickness. As the gas velocity increases, the wavy film entrains droplets from the surface, eventually disintegrating into droplets at the trailing edge.

Real-time bubble/droplet tracking above 1kHz

気泡や液滴のリアルタイム追跡と統計量解析

Flow Measurement and Instrumentation, "In-situ 1-kHz real-time particle tracking velocimetry using high-speed streaming camera", T.Ichimura(M2)

We have firstly succeeded in real-time (in-situ) detection and tracking of bubbles and droplets at exceeding 1,000Hz for measuring the number, 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

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.

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.