Study of heat transfer coefficients of multiple high-pressure fan-shaped water impinging on the lower surface of high-temperature steel billets

The lack of research on the boiling heat transfer coefficient on billet surfaces during the high-pressure fan-shaped water descaling process significantly affects the cooling, quality, and rolling efficiency of the billet surface. This paper utilizes the Eulerian multiphase flow model in Fluent 19.0 software to simulate the boiling heat transfer behavior of multiple high-pressure fan-shaped water jets impinging the surface of high-temperature steel billets during descaling. The study highlights the correlation between the boiling heat transfer coefficient and three key parameters: the Reynolds number, dimensionless target distance, and dimensionless temperature. The simulation’s accuracy was validated by comparing the simulation results against experimental data. Findings indicate that the boiling heat transfer coefficients were respectively higher in the stagnation area, the lower side of the overlap zone, and at the edges of the flow strands on the billet surface, reaching up to approximately 6000 W·m⁻²·K⁻¹. Additionally, the heat transfer coefficients were higher in the downstream region compared to the upstream area. The boiling heat transfer coefficient increased by 13.7 % and 9.38 % as the Reynolds number increased from 278,031 to 340,486 and as the initial temperature increased from 1373.15 K to 1573.15 K, respectively. On the other hand, the boiling heat transfer coefficient decreased by 19.0 % when reducing the target distance from 20 de to 54 de. Finally, a function was established to describe the boiling heat transfer coefficient based on the Reynolds number, dimensionless target distance, and dimensionless temperature.