Experimental results by IR-thermography on convective heat transfer inside a ribbed rectangular channel

This paper presents the first experimental results on local heat transfer characteristics of a forced air-flow through a rectangular channel with transverse ribs on the lower wall. The channel is 120-mm wide and 12-mm high, and it is operated at fixed heat flux on the lower wall while keeping thermally insulated all others; ribs have a square cross-section of 4 mm side and are made of a non-conductive material. Local heat transfer characteristics are investigated by measuring the temperature field on the surface of the ribbed heated wall by means of IR-termography (optical access in the infrared region to the inside of the duct is provided by a germanium window mounted in the upper wall). Data here presented are obtained at Re=5400 for three values of the rib pitch-to-height ratio, namely, p/e =10, 20, 40; for all these configurations, the wall temperature shows similar streamwise-distributions with a minimum where flow reattaches; the distance of this point from the rib backside increases with p/e.