Kyoto University · Engineering
Professor Noritaka Sako's research lab specializes in thermal management and fluid dynamics in propulsion systems, with a primary focus on liquid film cooling in bipropellant rocket thrusters. The lab investigates the transient behavior of liquid films formed by wall-impinging jets, particularly under pulsed operation conditions, to mitigate heat soak-back and enhance thruster durability. Using high-speed imaging and infrared thermography, the lab analyzes film spreading, boiling-induced atomization, and heat transfer characteristics to optimize cooling efficiency and prevent thermal hazards. Their work bridges fundamental fluid dynamics with practical space propulsion applications, emphasizing performance enhancement and safety in reusable thrusters.
Figures are computed from collected data and may differ slightly.
In film cooling approaches, a film of liquid fuel is formed on the chamber wall of bipropellant thrusters to protect the chamber wall from high-temperature combustion gases. To optimize the amount of liquid fuel required to sufficiently cool a chamber wall in this manner without degrading the performance of bipropellant thrusters, the formation process of the liquid film needs to be understood. To this end, in this study, factors affecting the spread of liquid film were experimentally investigat
Characteristics of boiling-induced atomization appeared in the liquid film which formed on the heated metal plate by a wall-impinging jet were experimentally investigated. The boilinginduced atomization were visualized via magnified high-speed imaging. Simultaneously, the variation of the wall temperature was measured by an infra-red camera from back side. The droplet size distribution and the ejection velocity distribution of the disintegrated small spherical particles were analysed. Results sh
View Video Presentation: https://doi.org/10.2514/6.2023-0512.vid The liquid film cooling technique was employed in bipropellant thrusters to protect the thrust chamber from high-temperature combustion gases. Heat soak-back from the throat to the face plate occurs in the interval between each pulse firing event. A liquid jet would be injected onto the superheated wall in pulse firing operation. To gain experimental knowledge for contributing to effective cooling and hazard prevention of thrusters
In a bipropellant thruster, a part of the liquid fuel is injected onto the combustion chamber wall to form a liquid film, which protect the wall from combustion gases. Particularly in the pulse operation, the fuel is injected onto a heated wall with temperature gradient formed by heat soak back from the nozzle throat. In this study, the transient processes of film formation and of wall temperature distribution were visualized by a high-speed imaging and an infrared camera, respectively. The beha
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