UBC Theses and Dissertations
Finite element simulation of water cooling process of steel strips on runout table Xu, Fuchang
This study engages in acquiring reliable heat transfer data from experimental tests using a test facility of industrial scale for an effective FE simulation of the water cooling processes of steel strips on run-out table (ROT). General 2D FE programs are developed for the direct and inverse heat transfer analyses. Both the Flux Zoning Method (FZM) and Flux Marching Method (FMM) are proposed to specify the heat fluxes in the inverse analysis. Parametric studies have been conducted and show that the direct analysis program may produce results with a higher accuracy, and that the FZM and FZM are suitable for obtaining an accurate relationship between the heat flux and the surface temperature in the impingement zone and in the parallel zone, respectively. The direct numerical investigations show that the isothermal condition does not exist for thermocouples (TC) with separate measuring junction in the water cooling process, and that the temperature difference between the two separate TC wires is affected strongly by the conduction of the surface TC wires in the impingement zone and by the progressing speed of black zone front in the parallel zone, respectively. The numerical analyses also show that the horizontal distance between TCs should be less than 8-10 mm to warrant a real 2D inverse calculation, and that there is a minimum depth for the embedded TCs for an undisturbed surface temperature field. The inverse analysis results of experimental tests show that the heat transfer behaviour at the stagnation for stationary plates is mainly and greatly affected by the water temperature, slightly by the steel grade and hardly by water flow rate. By contrast, the cooling behaviour in the parallel zone is obviously affected by the flow rate and hardly by the water temperature. It is also found that the plate’s motion evidently reduces the heat flux magnitude. Extensive 1D simulations to the cooling processes of the steel strips on an industry ROT show that the final coiling temperatures of steel strips may be predicted with a reasonable accuracy. Also, initial studies show that 2D modellings may have modest impact on the accuracy of the coiling temperature prediction.
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