Sea-level static tests of rocket–ramjet combined cycle engine model

Sadatake Tomioka, Masao Takegoshi, Toshinori Kochi, Kanenori Kato, Toshihito Saito, Kouichiro Tani

Research output: Contribution to journalArticlepeer-review


A rocket–ramjet combined cycle engine model, embedding twin rocket chambers driven with gaseous hydrogen and oxygen on the top wall side of a scramjet flowpath, was tested in its ejector-mode operation under sea-level static conditions. Gaseous hydrogen was also injected through secondary injector orifices to pressurize a ramjet combustor located downstream of the rocket chambers. Mixing between the hot rocket plume and cold airflow as well as combustion of residual fuel within the plume with the airflow caused entropy and static pressure increases in the constant-area mixing duct in the original flowpath design, resulting in a limited airflow rate. The mixing duct was redesigned to incorporate divergence from its onset to counter the pressure rise. With the diverging flowpath configuration, the airflow rate was increased by 40 percent. However, this modified flowpath geometry resulted in the formation of a low-speed area, through which the pressure rise in the ramjet combustor penetrated the mixing duct and reduced the incoming airflow rate. Without mechanical contraction near the engine exit, increasing pressure in the diverging portion of the flowpath was difficult, which in turn, resulted in poor mixing between the airflow and the rocket plume. Balancing these factors and additional mixing enhancement are required. The engine performance is then summarized.

Original languageEnglish
Pages (from-to)381-390
Number of pages10
JournalJournal of Propulsion and Power
Issue number3
Publication statusPublished - 2021
Externally publishedYes

ASJC Scopus subject areas

  • Aerospace Engineering
  • Fuel Technology
  • Mechanical Engineering
  • Space and Planetary Science


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