Studies on a pressurized swirl injector bi-propellant used in rocket-motor

Abstract

The process of fuel injection in combustion chambers is of vital importance, under several aspects, for the ideal operation of each motor. The responsible element for the introduction of liquid and gaseous propellants in the combustion chamber of rockets and for the transformation of liquid masses in sprays is the injector, that converts the potential energy of the propelants in kinetic energy, for the pressure fall in its interior, forming a jet or liquid sheet that dissolves in drops. Swirl type pressurized injectors, mono or bipropelants, are object of constant studies to understand its operation in rocket-motor with liquid propelant, because they produce conical liquid sheets and present a serie of differences in relation to the axial type in terms of improvement of the combustion process as a whole. The fast formation of a high number of drops, of convenient diameters, distributed in an extensive area, favors the vaporization mechanisms due to the high surface of all, that quickly vaporize and enter in combustion. Its production is a challenge for the techniques of conventional fabrication, because of the complexity, dimensions, work conditions and its fixation in the injection head. Injectors production from preexistent designs and the assembly of a structure which allowed the tests of the same, was the object of this work, that generated pieces in brass which allowed cold tests with the fluids kerosene and cut oil to confirm the formation of the hollow conical spray and hot tests with melted paraffin to confirm the formation of spherical drops of several sizes, which were measured in a profile projector, and analyzed by the process of test sieving, revealing the existence of drops within the range of those already found in literature. © 2009 by the American Institute of Aeronautics and Astronautics, Inc.