Hydraulic jumps and film spread characteristics of circular liquid jets impinging on inclined plates: experimental and numerical analysis

Abstract The hydraulic jumps caused by the impact of the jets of the free-surface liquids against the solid substrates are crucial phenomena in the cooling, cleaning and processing of materials. However, the combined effect of jet orientation and substrate inclination on the resultant film expansion and jump morphology is not well examined. The proposed research is aimed at experimentally and numerically investigating the dynamics of water jets, vertical, horizontal, and inclined, when they impact planar plates that are held at different angular dispositions. Experiments were conducted using a closed-circuit water loop, which had replaceable jet nozzles and a flexible plate-inclination system. High-speed imaging was used to visualize the flow, which allowed the detailed evaluation of the film dispersion, symmetry, jump radius, and instabilities formation. ANSYS Fluent was used to conduct computational studies based on a Volume-of-Fluid (VOF) formulation to solve the liquid-air interface and support the empirical observations. The calculated values of jump radius were observed to agree with the experimental values within a margin ±6%. Among the important discoveries are asymmetric jump zones that occur as a result of inclined jets, the formation of rope-like structures in unstable flow regimes, and stabilization that is manifested in downward jet impingement cases. The combined methodological framework provides a precise understanding of the complex interplay between the forces of inertia, gravity and slope gradient, thus explaining their combined effect in defining the nature of hydraulic jumps. The results provide practical recommendations to the optimization of jet-based surface cooling systems and fluid distribution equipment.