Numerical simulation of single-jet impact cooling and double-jet impact cooling of hot-rolled L-shaped steel based on multiphase flow model

Abstract

In this paper, numerical simulations of single-jet impingement cooling and double-jet impingement cooling processes of heated L-shaped steel are carried out using the VOF model. The SIMPLEC pressure–velocity coupling algorithm and realizable k-ε model are used for the solution. The effects of jet position, water flow, and jet distance in the single-jet condition are analyzed in the simulations. The distributions of impact pressure, turbulence kinetic energy, and Nusselt number were obtained, as well as the variation of the peak values of these three factors with the jet position, water flow, and jet distance. The water flow rate is 3–11 L/min, and the jet distance is 5–25 cm. The effect of the distance between the two nozzles on the jet cooling uniformity under the dual jet condition was also analyzed. The distance between the two nozzles was 15–45 mm. The results showed that the variation of water flow rate had a greater effect on the ability of jet cooling compared with the jet position and jet distance, and the heat transfer efficiency also increased gradually with the increase of water flow, but the increased rate of heat transfer efficiency decreased gradually. When the flow rate increased from 3 to 11 L/min, the maximum instantaneous cooling rates at 1/4 of the thickness of the short side upper side, long side upper side, short side lower side, and long side lower side positions increased by 38.9%, 48.5%, 48.2%, and 32.9%, respectively. To ensure that the jet does not shift, the jet distance should be less than or equal to 10 cm. In the case of the double jet, the nozzle distance is 1.5 cm, and the cooling uniformity of the cooling area between the two nozzles is better. The peak Nusselt number in the cooling area of each part under the double jet cooling condition increased by 5%, 9.4%, 10.2%, and 13.3%, respectively, compared with the single jet.

Numerical Analysis of Convective Heat Transfer in Quenching Treatments of Boron Steel under Different Configurations of Immersed Water Jets and Its Effects on Microstructure

“…Figure 4 shows the validation of the thermal field where three cooling curves are compared: one experimental and two correlations used in the numerical simulation; the Equation (10) was obtained by an eight-order polynomial regression of plotted heat-transfer coefficient as a function of time, from the experimental data obtained: (10) This correlation was introduced as a user-defined function, UDF, into the solution of the energy equation. The second expression employed, Equation (11), is programmed by default in the software.…”

“…This correlation was introduced as a user-defined function, UDF, into the solution of the energy equation. The second expression employed, Equation (11), is programmed by default in the software.…”

“…Xia-wei Yang et al [9] evaluated the velocity and uniformity of the fluid-dynamic field in two types of quenching tanks (with and without agitation); they determined that for the case without agitation, the flow is not regular, while with the model with agitation, the flow fields present areas of better regularity. Currently, there are new contributions where the transient-state energy equation is solved simultaneously using CFD to determine the evolution of the temperature of a solid body within the computational domain [10][11][12]. Gomes et al [12] developed a mathematical model to predict the temperature profile in a steel pipe and studied the effect of water-flow rate and pressure in the heat treatment.…”