Evaluation of heat transfer in quenching processes with impinging liquid jets

Abstract

Liquid jets and sprays often are used in metal-working processes like hot rolling, heat treatment or casting for intensive cooling of hot metal specimen and surfaces. Due to the potential evaporation of the quenching liquid during boiling, the local fluid flow as well as the heat transfer are extremely dynamic processes. Therefore, a numerical simulation model has been developed for flow and heat transfer to analyze the entire cooling process in the jet quenching process including all boiling regimes.In this contribution the focus is on quenching of hot metal surfaces with impinging water jets. The impingement liquid jet flow behavior and the wetting front behavior of the jet on the surface of a plate have been analyzed. As result of the simulations, the local surface temperatures and the temperature gradients at the cooled surface are evaluated as well as the local heat transfer rates.The model validation is done by means of different experimental approaches. Therefore, the progression of the wetting front at the quenched surface and the temperature distribution on the back side of thin metal plates during jet quenching has been evaluated.