Experimental Study And Numerical Simulation Of Laminar Cooling Of Matrix Arranged Nozzles

With the increasingly fierce competition in the steel market and the maturity of size control technology,metal performance indicators have become the focus of competition in the international steel industry.The performance of steel plates is mainly determined by the heat transfer process(that is,the cooling rate,final cooling temperature,and steel plate temperature).Uniformity).Although the application of laminar cooling technology in the past 10 years has greatly improved production efficiency,there are still many problems,such as the uniformity of temperature inside and outside the steel plate,uneven stress and warpage of the steel plate.The key to improving the cooling control technology after rolling is to accurately understand the parameters affecting the cooling after rolling.However,due to the complexity of transient impinging boiling heat transfer during laminar cooling,there are many influencing factors,this complicated regular distribution is very difficult to control the laminar cooling technology.This paper carried out the work of building an experimental platform,experimental research and numerical simulation in three aspects,and independently built a matrix-arranged nozzle laminar cooling experiment system.The entire system is divided into billet heating system,transmission system,nozzle adjustment system,jet system and The six subsystems of the temperature acquisition system.In this paper,static experiments and dynamic experiments were carried out respectively.Through the experiments,the changes of the steel plate temperature under different working conditions were obtained,and the effects of various parameters on the heat transfer process of the steel plate during the laminar cooling process were analyzed in detail.In the numerical simulation part,two-dimensional and planar simulations were carried out.Fluent simulation software was used to numerically simulate the flow field and temperature of the jet impacted by a single nozzle,and analyze the obtained temperature field and velocity field.The main conclusions of experimental research and numerical simulation are as follows:(1)The temperature at which the steel plate exits the furnace is reduced from900? to 800?,and the average temperature drop rate is reduced by 14.5%.The temperature difference between the points is reduced,and the maximum temperature difference is reduced by 32%.(2)The jet height was increased from 475 mm to 485 mm,and the average cooling rate was reduced by 23.7%.The maximum temperature difference was reduced by48.6%.(3)When the running speed of the steel plate is increased from 1m / min to 3m /min,the temperature of each temperature measuring point on the surface of the steel plate drops sharply,and the fastest temperature drop point is reduced by 39.7%.(4)When the water spray volume is increased from 0.1m3/h to 0.16m3/h,the average temperature drop rate of the billet surface increases by 1.44 times,and the maximum temperature difference of the billet surface exhibits a parabolic linear change.The temperature uniformity of the near surface of the steel plate shows a tendency to increase after decreasing.There is an optimal value of 0.125m3/h in this experiment,which makes the temperature uniformity on the surface of the steel plate the highest.(5)Under different jet velocity conditions,the magnitude of the increase in the velocity of the water flow axis is different.When the nozzle velocity is small,the magnitude of the increase in the velocity of the water flow axis is large.For example,when u = 2m/s,the velocity of the water flow axis increases from 2m/s to 3.3m/s,an increase of 65%.When the jet velocity is larger,the velocity of the water flow axis increases less,for example,when u=10m/s,the velocity of the water flow axis increases from 10m/s to 10.25m/s,an increase of 25%.(6)When the nozzle jet velocity is increased from 2m/s to 6m/s,the temperature of the stagnation zone on the surface of the steel plate sequentially decreases by 5.4%and 7.9%,and the maximum temperature difference between the stagnation zone and the wall jet zone decreases by 44.9% and 26.2%.