Liquid jet impingement has many industrial cooling applications such as metal manufacturing and steel cooling on run‐out tables (ROT). The development of the wetting front around the impingement point of a jet is central in jet impingement cooling. In this paper, the effects of moving target surface and jet Reynolds number on wetted zone and on the formation and location of hydraulic jump (HJ) are explored through a series of industrial‐scale experiments of an impinging circular free surface long water jet with high Reynolds number of 11 000–50 000 and industrial jet parameters. The moving test surface impacts the radial evolution of circular wetted zone in all directions and alter the circular HJ at the wetting front into a non‐circular contour that depends on the jet Re number. The limited relations in the literature do not represent these measured shapes and do not appropriately predict radii of HJ in industrial scale. A new correlation for radius of non‐circular HJ has been derived in this study that compared more accurately to the experimental data. Numerical simulations of radial impingement flow on moving surface were performed using a variant of k–ε turbulent model and results are compared to the experimental data. The computational results for the wetting front were found to be close to the experimental data indicating the appropriate performance of the turbulent model.

A circular turbulent long jet has been assessed numerically using the volume-of-fluid method to examine the hydrodynamics of a long jet before impingement and to inspect the flow structure of a radial thin layer spreading over a flat plate after impingement. Typical steel mill industrial parameters are used in the model. Comparative results are shown for laminar and turbulent jets with different turbulence models. Model results showed good agreement with the analytical solution available for global parameters and jet behaviour. The film thickness of the water layer over the plate, for more than 27 jet diameter, was measured by tracking free-surface. A hydraulic jump was detected and occurred within the radial zone in different shapes in laminar and turbulent modelling, respectively.

The hydrodynamics of impingement flow is a key partner of heat transfer analysis of run-out table (ROT) cooling. The long circular free-surface water jets with industrial parameters (e.g. Re = 16,000–50,000) were numerically simulated by laminar and two variants of turbulent k-ε and k-ω models where the effect of gravity is significant. The development of water impingement film was computed and compared with the experimental data which obtained from the ROT facility. The propagation of water flow over the impingement surface is better simulated by Shear Stress transition k-ω (SST) model. The impingement flow features such as jet deceleration before hitting wall and velocity and pressure profiles were compared with short jet data to explore common flow characteristics between the short and long jets. The effect of target surface on retardation of long turbulent liquid jet before incident is pronouncing as jet Reynolds number increased. However, the velocity reduction is not noticeable until where the speed of short jet starts decreasing. In impingement zone, the flow radial velocity varies linearly similar to short liquid jets which gravity effect is neglected. But, the velocity gradient was found higher which shows enhanced heat transfer for a long turbulent water jet. The dimension of impingement zone as an influential region in boiling heat transfer analysis is found smaller respect to the estimation which used in ROT modeling. The effect of local impingement pressure on saturation temperature is found important in stagnation zone which influences the prediction of heat fluxes by boiling heat transfer correlations up to 9%. This has to be considered in ROT modeling where the heat flux can be as high as 10 Mw/m2.

Cooling liquid jet impingement has many industrial applications such as metal manufacturing where the shape and the size of wetting area around impingement point is important in heat transfer analysis. A series of experiments on a moving surface with an impinging industrial-scale circular water jet is conducted to explore experimentally the wetting region and the hydraulic jump as the front of wetted zone. The effects of surface motion on the wetting zone and the formation and location of hydraulic jump upstream the impingement point is examined by changing systematically the surface velocity and the jet flow rates. The surface motion impacted the radial evolution of wetted zone in all direction and decreased the radius of non-circular hydraulic jump. However, higher jet flow rate suppressed its effect. Both surface velocity and jet velocity or their velocity ratio has to be considered in adjusting jet space along a jet-line in industrial cooling application.

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