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    • Design of Sub-scale Rocket-Ramjet Combined Cycle Engine Model

    Paper number

    IAC-05-C4.5.03

    Author

    Mr. Takeshi Kanda, Japan Aerospace Exploration Agency (JAXA/Kakuda Research Center), Japan

    Coauthor

    Mr. Sadatake Tomioka, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan

    Coauthor

    Mr. Shuichi Ueda, Japan Aerospace Exploration Agency (JAXA), Japan

    Coauthor

    Mr. Kouichiro Tani, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan

    Coauthor

    Dr. Yoshio Wakamatsu, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan

    Year

    2005

    Abstract
    To conduct tests of a rocket-ramjet combined cycle engine, a sub-scale model was designed. The model will be tested at the Ramjet Engine Test Facility of Japan Aerospace Exploration Agency under a sea-level static, Mach 4, Mach 6 and Mach 8 flight conditions. 

The engine operates in the ejector-jet, ramjet, scramjet and rocket modes. The engine model is composed of a convergent-divergent duct and two rockets in the duct. Fuel injectors are equipped for the secondary combustion in the ejector-jet mode and the primary combustion in the ramjet mode. The rockets works as a primary flow source in the ejector-jet mode, an igniter in the ramjet mode, and a gas-generator in the scramjet mode. In the ejector-jet mode and the ramjet mode, combustion gas will choke at the exit of the engine. 

Each component of the engine was demonstrated experimentally and physical models were constructed. The rockets will operate in several conditions because of several operating modes of the engine. The sub-scale rockets were designed and tested experimentally in various mixture ratios and chamber pressures.1 The ejector section composed of the rockets and the airflow duct was designed with a suction model, and suction performance of the ejector was examined experimentally.2,3 The pseudo-shock in the divergent duct downstream of the rockets was modeled with the momentum balance model.4 The starting position of the shock and the pressure in the duct was calculated with the model. Combustor tests were also conducted under each operating mode.5-7 Tests of the inlet have been conducted. Design of the sub-scale engine model was based on these results. 

The engine model is 3 m long, its height is 0.2 m and its width is 0.25 m at the entrance. The engine model is composed of the inlet to throat section (the upstream section) and the throat to exit section (downstream section). The pressure in the rocket chamber is 3.3 MPa, the air flow rate is 2.6 kgs-1, and net thrust is 4.7 kN under the sea-level-static, design condition. The downstream section is now under production. The upstream section is now under design process and will be produced by the end of FY2006. The primary objective of the engine model tests is to evaluate its performance in the ejector-jet mode at sea level static conditions.  As airflow will choke at the throat position under the sea-level static conditions, the design of the upstream section have little influence on the performance of the combustor (i.e., the downstream section), so that the first tests are scheduled in FY2006 prior to the completion of the upstream section, with the downstream section alone.  

1) Tomioka, S., et al., “Design and Validation of Injectors for a Rocket of a RBCC Engine,” 2nd Asian Joint Conference on Propulsion and Power 2005 Paper, C2-3, Jan. 2005. 
2) Aoki, S., et al., “Aerodynamic Experiment on an Ejector-Jet,” to be published in Journal of Propulsion and Power. 
3) Tani, K., et al., “Aerodynamic Characteristics of the Combined Cycle Engine in an Ejector Jet Mode,” AIAA Paper, 2005-1210, Jan. 2005. 
4) Kanda, T., and Tani, K., “Momentum Balance Model of Flow Field with Pseudo-Shock,” AIAA Paper, AIAA-2005-1045, Jan. 2005. 
5) Kato, K., et al., “Experimental Study of Downstream Combustion Ramjet-Mode,” AIAA Paper, 2005-0617, Jan. 2005. 
6) Kobayashi, K., et al., “Performance of a Dual-Mode Combustor with Multi-Staged Fuel Injection,” AIAA Paper, 2004-3482, Jul. 2004. 
7) Kato, K., et al., “Experimental Study of Combined Cycle Engine Combustor in Scramjet Mode,” AIAA Paper, 2005-3316, May 2005.
    Abstract document

    IAC-05-C4.5.03.pdf

    Manuscript document

    IAC-05-C4.5.03.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.