TY - JOUR
T1 - Sea-level static tests of rocket–ramjet combined cycle engine model
AU - Tomioka, Sadatake
AU - Takegoshi, Masao
AU - Kochi, Toshinori
AU - Kato, Kanenori
AU - Saito, Toshihito
AU - Tani, Kouichiro
N1 - Funding Information:
The authors are thankful for all Ramjet engine test facility (RJTF) staff members for their contributions on the tests. The authors are also thankful for the staff from Kawajyu-Akashi Engineering Company, Ltd., for its contributions on the engine fabrication and test preparation.
Publisher Copyright:
© 2021 by the authors.
PY - 2021
Y1 - 2021
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85117420958&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85117420958&partnerID=8YFLogxK
U2 - 10.2514/1.B37683
DO - 10.2514/1.B37683
M3 - Article
AN - SCOPUS:85117420958
VL - 37
SP - 381
EP - 390
JO - Journal of Propulsion and Power
JF - Journal of Propulsion and Power
SN - 0748-4658
IS - 3
ER -