Experimental Study Of Natural Convection Heat Transfer In An Enclosed Vibration Cavity

摘要

Experimental study has been implemented to elucidate an affect of mechanical vibration at normal gravity on natural convection in cubic enclosure side (L=120mm) filled with air ( 14Pr=0.71)"> at two amount of heat flux (. The enclosure was comprised of two vertical and opposed surfaces. The right wall was heated at uniform heat flux where the left wall cooled was maintained at 14Tc"> , surrounded by four other adiabatic surfaces. Vibration stresses were applied to this heat transfer cell by mounting it vertically on the armature of electrodynamic vibratior. The experiments were carried out at for Rayleigh number range ( 147*107-4*108)"> and aspect ratio equal (1), frequencies from 2to 8 Hertz at 14q""> =85 14Wm2"> and from 3 to 9 Hertz at 946.017 14Wm2"> ). In the high Rayleih number case (Ra=4* 14108"> ), the gravitional thermal convection dominates, and the vibration motion does not enhances the heat transfer remarkably. In contrast, in low Rayleigh (Ra=7* 14107"> ), the vibration thermal convection is dominant, and the vibration enhaces the heat transfer rate significantly. In addition, the higher the vibration frequency is, the quicker the steady stateis reached and for two cases of Rayeigh number at ascending frequencies is in general higher than that descending frequencies.