Design and Cold-flow Test of Bi-propellant Injectors for a Moon Exploration Thruster

摘要

In this paper, design and cold-flow test of bi-propellant injectors for a 420 N-class moon exploration thruster were performed. As a bi-propellant injector, bi-swirl coaxial injectors were determined. Three types of bi-swirl coaxial injectors such as closed-closed, open-open, and screw-screw geometries, were manufactured from the swirl injector design procedure based on the swirl injector geometric constant K. Cold-flow tests were conducted to verify the design procedure. In the present study, pressure drop, discharge coefficient, and spray angle were measured and compared with the design values. Due to pressure losses in the feed line and manifold, measured pressure drops were slightly larger than the design pressure drops. However, measured discharge coefficients and spray angles were not much different from the design discharge coefficient and design spray angle. In the case of bi-injection, the results of pressure drops and discharge coefficients were equal to those in single-injection, while the spray angles of outer injectors were decreased and the spray angles of inner injector were increased in bi-injection.