ROCKET ENGINE COAXIAL INJECTOR LIQUID-GAS INTERFACE FLOW PHENOMENA

Coaxial injectors are used for the injection and mixing of propellants H-2/O-2 in cryogenic rocket engines. The aim of the theoretical and e xperimental investigations presented here is to elucidate some of the physical processes in coaxial injector flow with respect to their sign ificance for atomization and mixing. Experiments with the simulation f luids H2O and air were performed under ambient conditions and at eleva ted counter pressures up to 20 bar. This article reports on phenomenol ogical studies of spray generation under a broad variation of paramete rs using nanolight photography and high-speed cinematography (up to 3 x 10(4) frames/s). Detailed theoretical and experimental studies of th e surface evolution of turbulent jets were performed. Proof was obtain ed of the impact of internal fluid jet motions on surface deformation. The m = 1 nonaxisymmetric instability of the liquid jet seems to be s uperimposed onto the small-scale atomization process. A model is prese nted that calculates droplet atomization quantities as frequency, drop let diameter, and liquid core shape. The overall procedure for impleme nting this model as a global spray model is also described and an exam ple calculation is presented.