SHEAR COAXIAL INJECTOR ATOMIZATION PHENOMENA FOR COMBUSTING AND NON-COMBUSTING CONDITIONS

Measurements of liquid oxygen (LOX) drop size and velocity in a uniele ment liquid-propellant rocket chamber are presented along with complem entary measurements of drop size/velocity for simulants under cold flo w conditions. The drop size comparisons between the cold flow and hot- fire conditions showed that the drops were larger for combusting condi tions. This observation is argued to be consistent with effects due to differences in the flow fields between hot-fire and cold flow conditi ons and more rapid vaporization of smaller drops under combusting cond itions. The use of the phase Doppler particle analyzer (PDPA) in obtai ning temporally averaged probability density functions of drop size in a harsh rocket environment has been demonstrated. The PDPA measuremen ts indicate that the atomization process is characterized by either th e presence of nonspherical liquid structures or the production of exte nsive dense drop regions under these conditions. Finally, the need for more extensive studies under a wider variety of chamber conditions is indicated.