In order to understand the characteristics of the Self-field MPD thruster with a discharge chamber diameter of 2cm, a ground experiment system was constructed and the thrust characteristics were obtained. For the power supply system, a capacitor bank using an electric double-layer capacitor and IGBTs was adopted, and it was confirmed that rectangular discharge current pulses could be output at arbitrary times. In the operation check of the experimental system, the discharge current, discharge voltage, and ion saturation current remained constant during 2ms, confirming the quasi-steady operation of the small MPD thruster for 2ms. Thrust measurement experiments were conducted using argon as the propellant, and a thrust force of 0.9N was confirmed at a maximum discharge current of 2.2kA. The measured thrust was proportional to the square of the discharge current. Therefore, it was confirmed that electromagnetic acceleration was dominant. As the highest propulsive characteristics, a specific impulse of 1800s and a propulsive efficiency of 2.3% were confirmed.

JAXA is currently studying the pre-cooled turbojet engine (PCTJ) to be installed in a hypersonic transport. As a device to reduce exhaust noise at takeoff, a mixer-ejector that is applicable to a rectangular hypersonic nozzle having a complicated geometry with an external ramp has been proposed and tested. The ejector introduces the low-speed secondary flow into the high-speed main jet and reduces the exhaust velocity by mixing. As a result, the mean jet velocity decreases and the jet noise decreases. A 1%-scale mixer-ejector was fabricated, and the mixing process between the main jet and the secondary flow was visualized using Mie scattering of water droplets. The direct relationship between the degree of mixing and the amount of noise reduction was investigated.

Magsail is a space propulsion system using the interactions between the solar wind and the magnetic field generated by the onboard coils. Magnetoplasma sail is a propulsion system that increases thrust by expanding the magnetosphere through plasma injection from the spacecraft. There are two mechanisms on the magnetospheric inflation: method using frozen-in of magnetic field to carry magnetic field lines by high dynamic pressure plasma and method using the diamagnetic current by thermal plasma, which is called the ring current. We investigated the effect of the dynamic pressure and thermal pressure on the MPS thrust performance used electromagnetic hydrodynamic simulation. It was shown that the ring current is enhanced by adding dynamic pressure to the thermal plasma and increases thrust gain. The high thrust gain over 2.25 was obtained at β_th = 0.5 - 2 and β_k = 4 - 8. However, the thrust is reduced because the super magneto acoustic wave region is generated in the magnetosphere, which prevents the propagation of thrust in large β conditions. The wide parameter survey reveals injection plasma parameter regions where thrust reduction is restrained and high thrust gain is obtained.

The effect of wingspan of the compound helicopter was experimentally investigated since the aerodynamic interaction between the rotor and wing affects the hovering performance of the compound helicopter. The thrust and torque of the rotor and the wing download were measured by varying the wingspan and vertical distance between the rotor and wing using a 1/14 scaled experimental model of the rotor and wing. The results show that the wing download increases as the wing span increases and it is maximum as the wingspan is 90% of the rotor diameter. Also, the wing download is maximum as the vertical distance between the rotor and the wing is 40% of the rotor radius.

Indoor flight experiment is conducted to verify the effectiveness of plasma synthetic jet actuator (PSJA) in improving aerodynamic characteristics of small unmanned aerial vehicle (UAV). It is required to realize small radius of turn that enables indoor experiment and low speed where the actuator exhibits high efficiency. Such requirements are satisfied by flat turn with side force fin, the vertical wing to produce a centripetal force. The effect of lift enhancement is quantified by the increase in aileron deflection caused by operation of PSJA on the outside wing. The results of flight simulations based on force measurement experiment for an airfoil model also support the validity of the proposed method.

The changes in the flow field and combustion behavior of a scramjet combustor with a cavity flameholder under boundary layer bleeding condition were investigated by direct imaging, PIV measurement and numerical calculations, at the mainstream conditions of Mach number of 2.5 with total temperature of 580--760K and total pressure of 0.6MPa. Hydrogen gas was used as fuel, and the ignition was forced by precombustion gas injection. From PIV measurement and numerical calculations, it was found that the boundary layer bleeding decreased the static pressure, the density and the static temperature of the mainstream and increased the maximum velocity and the velocity of the boundary layer. Direct imaging of the combustion experiments and numerical calculations showed that the boundary layer bleeding increased the momentum flux of the mainstream and changed the interaction between the precombustion gas jet and the mainstreams, which in turn changed the static temperature and the local equivalence ratio distribution inside the cavity flameholder, resulting in a change in the combustion behavior more favorable to flameholding. It was concluded that the increase in momentum of the mainstream could improve the flameholding performance.