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Description
In order to characterise the maximum possible cooling rate for AHSS with non oxidizing gas a new test bench has been constructed at VKI, combining 1 central round jet surrounded by 6 jets. The facility allows jet Reynolds number up to 200.000, value for which very few experimental data are available in the literature. Results are obtained for different normalised standoff distances Z/D (ratio between the outlet of the jet and the plate divided by the diameter of the round jet) and for different tilt angles of the plate with respect to the array of jets. The heat transfer coefficient is obtained by application of the active quantitative infrared thermography. Plate at constant and uniform heat flux is used. The thermograms are analysed by an in-house DIP program allowing the determination of the heat transfer coefficient mapping. A mean heat transfer coefficient is defined on a characteristic cell. The evolution of the Nu-number obtained by increasing the Reynolds number to this high value will be presented.
The experimental data are compared with numerical simulation for the validation of turbulent heat transfer. The numerical simulations are afterwards performed taking into account the industrial temperature (higher temperature difference between the jets and the metal sheet). A comparison of the heat transfer coefficient and the Nusselt number is made between the laboratory and industrial context.
Keywords
heat transfer, impinging jets, ARN, Reynolds, Nusselt