EXPERIMENTAL-STUDY OF FREE-CONVECTION AT AN INDOOR GLAZING SURFACE WITH A VENETIAN BLIND

A Mach-Zehnder interferometer was used to measure the laminar free con vective heat transfer rate from an isothermal vertical surface adjacen t to a set of aluminum Venetian blinds. Local and average hear transfe r data were obtained at three different blind-to-plate spacings, and a t four different blade angles. Data are presented up to a Rayleigh num ber of Ra = 3 x 10(7), based on the distance from the leading edge. Fl ow visualization results that illustrate the cellular flow patterns be tween the blades are also presented. Overall, it was found that the fl ow field and local heat transfer distribution on the surface can: be s ignificantly affected by the presence a Venetian blind. When placed cl ose to the surface, the blind causes a strong periodic variation in th e local Nusselt number distribution. However, for all cases studied th e average Nusselt number was within 13% of an isolated vertical flat p late at the same Rayleigh number.