Deformation and rebounding dynamics of the liquid jet impinging on a heated solid surface under Leidenfrost conditions.

We examine the hydrodynamics of the liquid jet obliquely impinging on a heated solid surface under Leidenfrost conditions, where the fast boiling of the liquid near the solid surface creates a stable vapor layer. Understanding the characteristics of a liquid jet impinging on a heated solid surface is important as various industrial processes involve cooling solid materials by liquid jets. This study examines the behavior of the jet by varying impinging jet velocity, diameter, and angle as well as solid surface temperature. Experiments reveal distinct jet flow characteristics depending on the jet impinging conditions. Due to the lubricating effect by the vapor layer, the impinging jet under Leidenfrost conditions retains a sufficient amount of energy during deformation. Thus, the liquid detaches from the solid surface and forms a rebounding jet after impingement. The shape of the deformed jet by impingement is determined by the balance between capillary pressure and hydrodynamic pressure. The vibration of the deformed liquid interface and the time-averaged rebounding jet characteristics are quantified by dimensionless parameters that capture the governing physics of the jet hydrodynamics. Furthermore, cooling heat flux by liquid jet impingement is estimated by analyzing energy balance at the liquid-vapor interface.