Experimental Study of Cavitation and Hydraulic Flip Effects on Liquid Jet Characteristics into Crossflows

In this work, 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. To provide several conditions for orifice internal flow, different orifice diameters, injection pressure differentials, and shapes (sharp and round) of the orifice entrance were used. Photographs of liquid flow inside the orifice confirmed the internal flow condition. A stroboscopic light was used to measure the liquid column breakup lengths and the liquid column trajectories. 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 lip 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

Steady Flow of Purely Viscous Shear-Thinning Fluids in a 1:3 Planar Gradual Expansion

Laminar flow of non-Newtonian fluid (shear-thinning) through a 1:3 planar gradual expansion is numerically investigated, for various Power-Law index (0.6, 0.8 and 1.0) and expansion angles (15, 30, 45, 60 and 90°) at different generalized Reynolds number (1 ≤ Reg ≤ 400). The study of these parameters effect on the flow pattern allowed the determination of the two critical generalized Reynolds numbers (Regcr1 and Regcr2), which correspond to the transition from the symmetric to the asymmetric flow and the appearance of the third recirculation zone respectively. The results showed that decreasing the Power-Law index or the expansion angle stabilizes the flow by increasing significantly the two critical generalized Reynolds numbers. In order to predict the two critical generalized Reynolds numbers, two correlations have been proposed