The Effects of the Ambient Pressure on Self-Pulsation Characteristics of a Gas/Liquid Swirl Coaxial Injector

Abstract

Self-pulsation gas strong influences on the atomization and mixing process and accompanies strong noises. A strong pressure and flow rate oscillation are detected when self-pulsation occurs. A sharp and narrow increase in frequency spectrum by self-pulsation is observed at a certain frequency. In this study, the effects of the ambient pressure on selfpulsation characteristics of a gas/liquid swirl coaxial injector are studied experimentally. A gas/liquid swirl coaxial injector is mounted in the high pressure chamber and the ambient pressure increased up to 1 MPa. The spray patterns were investigated according to the ambient pressure using digital camera and stroboscope. Also, acoustic and spray characteristics of self-pulsation are investigated with various injection and recess length conditions using acoustic device and laser system. From the results, it is found that the ambient pressure has great effects on self-pulsation and the mechanism of self-pulsation is suggested. Nomenclature do = inner orifice diameter Pc = chamber pressure Reg = axial gas Reynolds number Rel = axial liquid Reynolds number RR = recess ratio vg = axial gas velocity vl = axial liquid velocity ρg = gas density ρL = liquid density