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| Koji OKAMOTO / Associate Professor / Division of Transdisciplinary Sciences |
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Department of Advanced Energy / / Space System Science and Technology
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| Career Summary |
1997: Graduated, Faculty of Engineering, University of Tokyo
2002: Doctor of Engineering from University of Tokyo
2002: Research Fellow, University of Tokyo
2003: Postdoctoral of DGA, ONERA (
Office National d'Études et de Recherches Aérospatiales)
2004: Research Associate (Assistant Professor), University of Tokyo
2009: Associate Professor, University of Tokyo
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| Educational Activities |
Graduate school:
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| Research Activities |
Propulsion System and Thermo-fluid Devices in Aerospace Engineering Field
1) Ultra Micro Fluid Device:
An ultra micro gas turbine (UMGT) is expected to be advantageous for a compact and light-weight power generation system because of its high power and energy densities compared to solar cells, batteries, and fuel cells. The key issue of UMGT technology is how to prevent decrement of the performance and efficiency of each component. We are studying Wave Rotor and Tesla Turbine, innovative compression/expansion fluid devices, whose working principles are completely different from those of conventional turbo machineries. They compress or expand gas by applying unsteady shock wave propagation or fluid viscous force on the disc surface, so that they are expected to achieve better performance when they are miniaturized.
Wave Rotor (left), Tesla Turbine (right)
2) Ultra Micro Combustor:
Another key issue in UMGT technology is the miniaturization of combustors. It is difficult to achieve stable combustion in small combustors. In addition, heat loss to the surroundings becomes serious, leading to the performance decrement of the whole system. We are investigating a micro combustor combined with a heat exchanger (HEX Combustor). In this combustor, heat loss to the surroundings is minimized, and stable combustion will be achieved by preheating the premixture gas for the combustor.
HEX Combustor
3) Aero Acoustics of Sub- and Super-Sonic Jets:
Recently, restrictions on jet noise from aero engines have become severe. Therefore, comprehending the aero acoustic phenomenon and developing a method to suppress the noise is important. We conducted a basic experiment at the UT-Kashiwa Hypersonic and High-Temperature Wind Tunnel to observe the aero acoustic phenomenon in the sub-sonic jet flow. Another basic experiment was performed to investigate the strong pressure waves generated by impinging supersonic jets on the ground from a rocket engine, which may have an adverse effect on the payload at the launch of a rocket. This experiment was performed in collaboration with JAXA, and the acoustic phenomenon of impinging supersonic jets was carefully investigated.
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Literature
1) Okamoto, K. and Araki, M., "Shock Wave Observation in Narrow Tubes for a Parametric Study on Micro Wave Rotor Design," Journal of Thermal Science, Vol. 17, No. 2, pp. 134?140, 2008.
2) Okamoto, K. and Nagashima, T., "Visualization of Wave Rotor Inner Flow Dynamics," Journal of Propulsion and Power, Vol. 23, No. 2, Mar.?Apr., pp. 292?300, 2007.
3) Okamoto, K. and Nagashima, T., "Simple Numerical Modelling for Gasdynamic Design of Wave Rotors," Journal of Propulsion and Power, Vol. 23, No. 1, Jan.?Feb., pp. 99?107, 2007.
4) Nagashima, T., Okamoto, K., and Ribaud, Y., "Cycles and Thermal System Integration Issues of Ultra-Micro Gas Turbines," RTO-AVT-VKI Lecture Series 2005 "MICRO GAS TURBINES", 14?18 Mar., 2005.
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| Other Activities |
The Japan Society for Aeronautical and Space Sciences (JSASS)
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| Future Plan |
We are aiming to discover new possibilities and availabilities of propulsion / power generation systems in aerospace engineering by introducing innovative ideas and approaches. In addition to the present research topics, we are trying to study heat control and heat energy application in space. In these research activities, we are taking both numerical and experimental approaches and making good use of various experimental facilities, such as the UT-Kashiwa Hypersonic and High-Temperature Wind Tunnel.
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| Messages to Students |
To solve problems in the research activities, we need to consider how to apply our knowledge to the problems, as well as acquire knowledge. By pioneering a research topic, you will obtain a better creative ability.
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