Design and test of a resonance ignition system for green in-orbit propulsion systems

In the current study stem-nozzle designs for use with Hartmann-Sprenger Tubes documented in literature are discussed with regards to their applicability to resonance ignition systems. Based on these considerations a coaxial resonance igniter for GCH4/GOX is designed, also taking system aspects into account. By means of CFD simulations the passive heating performance of the igniter concept, as well as the auto-ignition process, is evaluated. Depending on the degree of thermal insulation of the resonator these calculations predict ignition to occur within milliseconds of operation. Igniter prototypes with a nominal thermal power of 4.5 and 30 kW are implemented using additive manufacturing. Coldflow tests demonstrate considerable heating for a wide range of operating conditions without adapting the nozzle-resonator-spacing to the nozzle pressure ratio. For the larger configuration successful ignition is achieved with feed pressures below 2 MPa, demonstrating the viability of the igniter concept. Due to minimal instrumation of the prototypes further investigations are required for determining the operational envelope of the implemented configurations.