Secondary Gas Injection in a Conical Rocket Nozzle

Data are presented on side forces generated by secondary gas injection in a 15° conical rocket exhaust nozzle. The side force was measured directly with a force transducer and the data examined in terms of an amplification factor I8/I8*9 where Is is the measured effective specific impulse of injectant, and Is* is the specific impulse of injectant for sonic flow into a vacuum. Injection was normal to the axis of the nozzle through a single circular orifice at a fixed point in the diverging portion of the nozzle. variety of ambient temperature gaseous injectants (H2, He, He + Ar, N2, CO2, and Ar) and orifice diameters were carefully studied. Injectant flow rate was varied for each configuration. The main propellant was hot gas (catalytically decomposed 90% H2O2), and motor conditions were held essentially constant. Aj = A = CD = FN = F =