| Career Summary |
1989: Graduated, Faculty of Engineering, The University of Tokyo
1995: Doctor of Engineering from The University of Tokyo
1995: Research Associate, The Institute of Space and Astronautical Science
1997: Visiting Research Associate, The University of Tokyo
2003: Chief Researcher, Japan Aerospace Exploration Agency
2003: Visiting Associate Professor, The University of Tokyo
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| Educational Activities |
Graduate School : Advanced Energy
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| Research Activities |
Fundamental research on ultimate gasdynamics related to development of transportation between space and Earth, planetary exploration, and deep space exploration, as well as their application to mission design and spacecraft development.
1) Development of thermochemical models for assessment of hypersonic flight environments
Very complicated thermal and chemical processes occur behind the strong shock waves produced ahead of the vehicle in hypersonic flight. Since these thermochemical processes determine the behavior of high-temperature gases in contact with the vehicle, it is of utmost importance to accurately model such processes for the assessment of aerodynamic performance and heat transfer rate to the body surface of the vehicle. In the ultimate gasdynamics laboratory of JAXA, fundamental research has been conducted in both analytical and experimental approaches, using a high-enthalpy wind tunnel, hypervelocity shock tubes, and high-speed shock tunnels (see Refs. 1 and 2).
2) Development of an advanced thermal protection system and its evaluation technologies
In addition to the gas-phase thermochemical processes stated above, it is important to understand gas-surface reactions in order to assess the aerodynamic heating rate of the body surface and to evaluate performance of the thermal protection system. In the ultimate gasdynamics laboratory of JAXA, development of the advanced thermal protection system is being undertaken in collaboration with the materials group and the mission design center. Advanced technologies to evaluate performance of the thermal protection system have been developed with verification using experimental facilities, such as the arc-heater and the inductively-coupled plasma wind tunnel (see Ref. 3).
3) Development of analytical tools for rarefied gases and intermolecular collisions
It is well known that rarefied gases at the high altitude and in the interplanetary space show different behaviors from those of dense gases, which can be regarded as continuum. In order to offer accurate predictions of gas behavior, development of numerical analysis technologies for rarefied gases is undertaken in the ultimate gasdynamics laboratory (Refs. 4-6). In addition, to improve gas-phase thermochemical models, numerical research is performed by molecular dynamic approaches and quantum chemical analysis (see Ref. 7).
4) Modeling and application of high-energy radiation heat transfer
As the flight velocity exceeds 10 km/s, which is the case for atmospheric reenty from interplanetary orbits, the influence of radiation heat transfer on the thermochemical behavior of gases becomes significant. In the ultimate gasdynamics laboratory, high-accuracy modeling of radiation processes is undertaken, with respect to the vacuum ultraviolet and ultraviolet wavelength ranges where radiation energy transfer is significant (Ref. 2). The radiation code is applied not only to the assessment of the radiative heat transfer rate for planetary entry vehicles in the mission design phase, but also to spectroscopic measurements of high-temperature gases to deduce the molecular temperatures and component concentrations (Refs. 8-10).
5) Applications to mission design
The technologies and tools described above are applied to conceptual studies and mission designs in future JAXA projects. For example, my coworkers and I are working on the development of future space transportation systems, planetary entry probes, and solid rocket motor nozzles. We are also undertaking early studies of planetary aerocapture systems, extremely-low-altitude satellites, and magnetic sails for deep-space exploration.
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Literature
1) Fujita, K., Otsu, H., Yamada, T., and Abe, T., "Assessment of Radiative Reentry Environment around MUSES-C Capsule," Journal of Japan Society for Aeronautical and Space Sciences, Vol.51, No.595, pp.419-426, (2003).
2) Fujita, K., Sumi, T, Yamada, T., and Ishii, N., "Heating Environments of a Venus Entry Capsule in a Trail Balloon Mission," Journal of Thermophysics and Heat Transfer, Vol.20, No.3, pp.507-516, (2006).
3) Fujita, K., Matsukawa, Y., Yamada, T., and Ishii, N., "Evaluation of Heat Transfer Rates of Venus Entry Capsules Along Flight Trajectories," AIAA Paper 2006-3580, 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, (2006).
4) Fujita, K., "Air Intake Performance of Air Breathing Ion Engines," Journal of Japan Society for Aeronautical and Space Sciences, Vol.52, No.610, pp.514-521, (2004).
5) Fujita, K., Inatani, Y., and Hiraki, K., "Attitude Stability of Blunt-Body Capsules in Hypersonic Rarefied Regime," Journal of Spacecraft and Rockets, Vol. 41, No.6, pp.925-931, (2004).
6) Fujita, K., "Particle Simulation of Moderately-Sized Magnetic Sails," Journal of Space Technology and Science, Vol.20, No.2, pp.26-31, (2005).
7) Fujita, K., T., "Assessment of Molecular Internal Relaxation and Dissociation by DSMC-QCT Analysis," AIAA Paper 2007-4345, 39th AIAA Thermophysics Conference, (2003).
8) Fujita, K., Sato, S., Abe, T., and Ebinuma, Y., "Experimental Investigation of Air Radiation from behind a Strong Shock Wave," Journal of Thermophysics and Heat Transfer, Vol.16, No.1, pp.77-82, (2002).
9) Fujita, K., Sato, S., Abe, T., and Otsu, H., "Electron Density Measurements behind Strong Shock Waves by H Beta Profile Matching," Journal of Thermophysics and Heat Transfer, Vol.17, No.2, pp.210-216, (2003).
10) Fujita, K., Mizuno, M., Ishida, K., Ito, T., Sumi, T., and Kurotaki, T., "Spectroscopic Diagnostics of Electrically Heated High Enthalpy Wind Tunnels," AIAA-2005-0173, 43rd AIAA Aerospace Science Meeting and Exhibit, (2005).
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| Other Activities |
The Japan Society for Aeronautical and Space Sciences (JSASS)
American Institute of Aeronautics and Astronautics (AIAA)
The Japan Society of Mechanical Engineering (JSME)
Japan Society of Fluid Dynamics (JSFD)
Member of JSASS Committee: Division of Transportation (1996-1997), Public information (2006-).
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| Future Plan |
In addition to improving the current state of technology through fundamental research, my coworkers and I plan to participate more actively in mission design and spacecraft development in order to extend the field of these applications. As one example of our activities, the concept of the Venus aerocapture system shown below was proposed in an early study.
Conceptual view of Venus aerocapture system using drag modulation
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| Messages to Students |
The areas of research in the ultimate gasdynamics laboratory range from fundamental research to mission-oriented projects. Every young researcher interested in our research is welcome to join. The only requirements are a passion for research and a dream for space!
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