National Aerospace Laboratory Ramjet Propulsion Research Division
National Aerospace Laboratory Rocket Propulsion Research Division
National Aerospace Laboratory Rocket Propulsion Research Division
National Aerospace Laboratory Ramjet Propulsion Research Division
National Aerospace Laboratory Ramjet Propulsion Research Division
There are limitations to achieve high specific impulse with rocket engine operations alone. However, in the flight at low altitude, combined engines with an airbreathing ramjet engine and a rocket engine can be expected to increase the specific impulse significantly in parallel operation. In this paper, the superiority in the specific impulse of the double-nozzle type of rocket-ram combined engine over the single-nozzle type combined engine was shown by performance calculations. Then, a double-nozzle type of rocket-ram combined combustor with a total thrust of 5kN was designed and experimentally tested with varying ratios of thrust produced by rocket and ramjet. The propellants are LOX/kerosene + hydrogen for rocket combustion and air-hydrogen for ram combustion. With the thrust chamber having different diverging half-angles, namely 10 deg 18 min, and 6 deg 40 min, thrust and pressure distribution along the common expansion nozzle were measured to investigate the effect of interaction of the expanding gases of rocket and ram on thrust. Enhancement of the specific impulse was experimentally verified. That is, the specific impulse which was gained in rocket-ram parallel operations, when the thrust ratio of rocket to ram was 50 to 50, was found to increase 90 percent over those in pure rocket operations.
ロケット-ラム複合燃焼器の実験
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