Atomization and Sprays

EFFECTS OF ORIFICE INTERNAL FLOW ON TRANSVERSE INJECTION INTO SUBSONIC CROSSFLOWS: CAVITATION AND HYDRAULIC FLIP

RESUMO

The effects of orifice internal flow, such as cavitation and hydraulic flip, on the breakup processes of the liquid jet injected perpendicularly into subsonic crossflows were studied experimentally. Orifice diameters, injection pressure differentials, and the shapes (sharp and round) of the orifice entrance were varied to provide several conditions for orifice internal flow. Photographs of liquid flow inside the orifice confirmed the internal flow condition. The liquid column breakup lengths, and the liquid column trajectories, which were believed to be important for designing injector/combustor and flame location, were measured using a stroboscopic light. According to previous research, the data were correlated by liquid/air momentum flux ratios and orifice diameters. The results showed that the liquid column trajectories in noncavitation flows and cavitation flows had a similar trend, but the liquid column trajectories in hydraulic flip flows had different results because the surface of the liquid in the hydraulic flip flows was detached from the inner wall of the orifice hole. As cavitation bubbles developed inside the sharp-edged orifice, the liquid jet became more turbulent and unsteady. Therefore, the liquid column breakup lengths in the cavitation flows were shorter than those in noncavitation flows. In the hydraulic flip, the breakup lengths had smaller values because the liquid jet diameter was smaller than the orifice diameter, and the acceleration waves occurring on the liquid column spread upstream of the orifice exit, then the breakup process on the liquid jet started from the orifice entrance.