NUMERICAL SIMULATION OF ATOMIZATION PROCESS OF SELF-IMPINGEMENT AND IMPINGEMENT BIPROPELLANTS

Hydrazine-based bipropellants are widely employed in liquid rocket engines of various aerospace propulsion systems for the space crafts such as satellites and missiles. To deepen the understanding of the atomization process of self-impingement and impingement hydrazine-based bipropellants, a three-dimensional three-phase volume of fluid (VOF) to Lagrangian particle tracking (LPT) conversion algorithm is developed based on the open-source platform OpenFOAM by introducing the effective liquid phase fraction. A coupled solver is further established for the VOF-LPT conversion algorithm. By combining the local grid refinement technology with the adaptive mesh refinement technology, the liquid interface is dynamically captured. The accuracy and validity of the developed coupled solver are well verified by comparing with the previous experimental results on a fuel jet in a cross flow. With the developed coupled solver, the effects of injecting velocity disturbance, fuel biased angle and jet velocity on the atomization progress of self-impingement and impingement hydrazine-based bipropellants are numerically investigated. The results indicate that the introduction of a moderate injecting velocity disturbance reduces the overall droplet size distribution and increases the specific surface area, thereby beneficial to improve the atomization efficiency. During the impingement stage of the fuel film and the oxidant film, the increase of the fuel biased angle and the jet velocity both promote the mixing between the fuel film and the oxidizer film due to the enhanced effective impingement momentum between the films. After the spray field is fully developed, the overall droplet size distribution increases with the increase of the fuel biased angle, and decreases with the increase of the jet velocity. In addition, since the mixing region of the fuel film and the oxidizer film is restricted by the fuel biased angle, the degree of mixing and breakup of the films is approaching a certain level with the increase of the jet velocity.