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形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2018-01-19, 資料番号: PA1810077000

形態: 図版あり, Physical characteristics: Original contains illustrations, Accepted: 2016-07-20, 資料番号: PA1710080000

To reduce the cost of space transportation, air-breathing engines are considered to be candidates for propulsion. However, to cover a wide range of flight speeds, the propulsion system has to operate in various modes to be efficient under incoming atmospheric-air conditions. The Japan Aerospace Exploration Agency is proposing a rocket-based combined cycle engine for operation under various condition, an ejector-jet mode being adopted for the low-speed regime. The suction performance ejector-jets has long been studied experimentally and numerically at JAXA, and little success has been achieved in explaining the deterioration of suction performance with high-temperature gas or light gas such as helium. In the present study, based on former models, a simple one-dimensional model was introduced incorporating the mixing effects of the primary flow (rocket flow) and secondary flow (induced air flow). The results were compared using several experimental and numerical data to check the plausibility of the model. It was found that if greater mixing occurs, suction performance is degraded, explaining the actual phenomena of the experiments., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: PA1610077000

2010 Asian Joint Conference on Propulsion and Power (March 4-6, 2010.), Miyazaki, Japan, 資料番号: AC1000137000, レポート番号: AJCPP2010-003

Two-stream flow model of ejector including heat and mass transfer was constructed by the comparison of the numerical simulations in the rocket-ramjet combined-cycle engine driven three different rocket gas; cold N2 gas, hot combustion gas and it within excess H2. The analysis of the ejector revealed that the heat and mass transfer from hot rocket plume with supersonic speed to cold airflow induced area change (expansion) of the airflow stream tube and the pressure rise in the constant-area section at the downstream of the rocket base. This pressure rise reduced the pumping performance of the ejector. To absorb the expansion of the airflow, the flowpath was changed from the constant area to the diverging area at the downstream of the rocket base. The numerical simulation in the modified engine demonstrated that the diverging-area section at the downstream of the rocket base improved the pumping performance.

資料番号: ARDS06125000

24th Congress of International Council of the Aeronautical Sciences (August 29-September 3, 2004.), Yokohama, Kanagawa, Japan, 資料番号: AC1000135000, レポート番号: ICAS 2004-1.11.1

A modified sidewall-compression-type scramjet engine was tested under M8 flight condition. A strut with a long tail led to a 60% higher maximum thrust increment than a strut with a truncated tail, while allowable fuel flow rate (i.e., the flow rate at engine unstart limit) was almost identical. To increase the allowable fuel flow rate and the maximum thrust increment due to combustion without engine unstart, distributed injection in vertical direction and installation of ramps in the isolator between the inlet and the combustor were applied. Distributed fuel injection led to a 30% higher maximum thrust increment than the uniform fuel injection, and the installation of the ramps also gave a 30% higher one than that in the engine without ramp. Gas-sampling at the exit of the engine with distributed fuel injection showed 88% of bulk combustion efficiency. Specific impulses of the maximum thrust increments, δIsp , of the modified engine were 60–80% higher than that of the original engine.

資料番号: PA0810076000