HEAT TRANSFER IN A CHANNEL WITH INCLINED TARGET SURFACE COOLED BY SINGLE ARRAY OF CENTERED IMPINGING JETS

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of equally spaced centered impinging jets for jet Reynolds numbers, Re = = 9300, 14400, and 18800. Air ejected from an array of orifices impinges on the heated target surface. The target plate forms the leading edge of a gas turbine blade cooled by jet impingement technique. The work includes the effect of jet Reynolds numbers and feed channel aspect ratios (H/d = 5, 7, and 9 where H = 2.5, 3.5, and 4.5 cm, and d = 0.5 cm) on the heat transfer characteristics for a given orifice jet plate configuration with equally spaced centered holes with outflow exiting in both directions (with inclined heated target surface). In general, It has been observed that, H/d = 9 gives the maximum heat transfer over the entire length of the target surface as compared to all feed channel aspect ratios. H/d = 9 gives 3% more heat transfer from the target surface as compared to H/d = 5 (for Re = 14400). Also, it has been observed that the magnitude of the averaged local Nusselt number increases with an increase in the jet Reynolds number for all the feed channel aspect ratios studied.