چكيده به لاتين
Abstract:
Due to the high transport phenomena rate and high applicability in different industries, impingement jets have always been an interesting subject for researchers. Additionally, because of unique attributions of porous medium, it has a lot of application in various industries. In this thesis the thermal performance of steady and pulsed impingement jets in the presence of metallic foams has been investigated. Comsol multi physics is used for the simulation of the problem. In steady state jet, the effect of various parameters including Reynolds number, nozzle to plate distance, porosity, permeability and the thickness of metallic foam blocks are analyzed. Also, in pulsative impingement jets, the performance of the jet with step and sinusoidal pulsative functions for various frequencies and amplitudes is investigated.
The results of this research suggest that with the presence of metallic foams, the general distribution of Nusselt number and the heat transfer rate on the target plate alter significantly. By utilizing the porous medium block, a more uniform distribution of Nusselt number can be achieved. In the case of pulsative jets, the results show a better thermal performance of the jets for high frequency and amplitudes of pulsation. In some cases the increase in performance can be up to 15 percent. For a more thorough analysis of the behavior of impingement jets, energy density flux vector and entropy generation equations have also been utilized.
Keywords: Impingement jet, Porous medium, Heat transfer
