Liquid Rocket Motor Combustion Stability Using Coaxial Injectors and Supercritical Droplet Combustion and Dynamics

Authors: Michael M. Micci; Vigor Yang; PENNSYLVANIA STATE UNIV UNIVERSITY PARK

Abstract:

Cold flow experiments with a full-size SSME preburner shear coaxial injector element using liquid and gaseous nitrogen at pressures up to 4 MPa showed that the intact liquid core decreased in length with increasing chamber pressure up to the critical pressure, after which it increased in length. Increasing the liquid to gas mass flow rate ratio resulted in an increase in the length of the liquid core. LDV measurements showed flow recirculation downstream of the LOX post. Results from a linearized model of the injector, combustion and vaporization processes compared well to unsteady pressure measurements made during liquid oxygen/gaseous hydrogen hot-fire tests. Vaporization and combustion of liquid droplets in both subcritical and supercritical environments have been studied systematically. A variety of liquid propellants and propellant simulants, including hydrobon and cryogenic fluids, in both steady and oscillatory environments were treated numerically. Because the model allows solutions from first principles, a systematic examination of the droplet behavior over wide ranges of pressure, temperuture, and ambient flow velocity is made possible. Results can not only enhance the basic understanding of the problem, but can also serve as a basis for establishing droplet vaporization and combustion correlations for the study of liquid rocitet engine combustion, performance, and stability. (AN)

Limitations:

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