Numerical Modeling of Hydrodynamic Instability of Swirl Coaxial Injectors in a Recessed Region

A homogeneous flow model has been developed to assess hydrodynamic instabilities of the liquid jet within the recessed region of swirl coaxial injector elements. A gaseous oxidizer (GOX) centered, liquid propellant swirl injector design has been employed in order to investigate mixing characteristics of the liquid and gas phases in the recessed region of the injector. The results show a vigorous swirling motion of the liquid flow once it is injected into the GOX post. The liquid surface fluctuates due to the interaction with the gas phase flowing at higher velocity. As the gas to liquid density ration increases the swirl motion and the fluctuation of the liquid phase tend to be more pronounced. Massflow rate of the liquid flow was also measured to investigate the well-known self-pulsation phenomenon of the swirl coaxial injector.