Heat Transfer Variation in Liquid Jet Impingement Due to Varying Body Forces

Abstract

In this research , simulation s of liquid jet impingement with different body forces are presented. These simulations were performed with the aid of a commercial multiphysics code called CFD -ACE+. The fluid properties o f the industrial coolant HFE 7000 were used for the simulations. The computational matrix included eight different simulations. In all cases vertical liquid jet (modeled as two dimensional and axi -symmetric) impinged normal to a heated plate. All these cas es were non isothermal with no boiling. The gravity was varied from 0 to 1.5 g in increments of 0.5 g. In four of these cases a low velocity (0.2263 m/s ) was used and the uniform body force directed towards the heater surface was varied in the increments o f 0.5 g, from 0 to 1.5 g. Similarly, four cases were simulated in which the velocity was higher, (0.5 m/s ). The Nusselt number increased with the increase in the body force for both velocity regimes. The heat transfer was influenced due to the varying gra vity levels more in the low velocity cases than in the high velocity cases. This was because the initial velocity in the low velocity cases was more significantly increased just before the jet impacted the plate. As the gravitational body force wa s increas ed to 0.5 g the heat transfer wa s enhanced. Further increase in the body force cause d further increase in Nusselt number . This increase wa s about 9.3 % in the average Nusselt number from 0 to 0.5 g, 6.6 % from 0.5 to 1 g and 4.9 % from 1 g to 1.5 g for the high velocity regime cases . The corresponding increases for the low velocity regime cases were 26%, 13% and 8 % respectively.