Seven types of gas-gas injectors involving two patterns were employed to conduct the flowrate characteristics tests at different back pressure conditions.An investigation on flowrate characteristics of one type of injectors was made at single propellant injection.The effects of inlet pressure of injector and back pressure as well as interaction between oxidizer injector and fuel injector on flowrate characteristics were investigated.Through the experimental measurements and fitting a mathematical expression

the formula of discharge coefficient was given.The results presented in this paper may provide valuable reference for the optimization design of the gas-gas injector for full flow staged combustion cycle engine.