Heat Transfer Enhancement of Gas Turbine Blades Using Coated Ribs with Nanocomposite Materials

The gas turbines work at temperatures higher than temperatures of metals melting point, therefore the internal cooled used compressor air in order to protect the blades from damage and increase operating life. The aim of this work is to enhance gas turbine blade cooling system. In this work, the flow and heat transfer in a rectangular cross section channel have been investigated at conditions that simulate those in air cooled turbine blades. The experimental study for the effectiveness of ribs using internal ribs then coating by composite nanomaterials including titanium carbide powder and thermal polymer with the heat transfer and flow characteristics for a fully developing of the turbulent flow through the rectangular passage at different Reynolds number ( Re =7450, 8940 and 10855) with channel hydraulic diameter of (0.03664 m) at constant surrounding hot air temperature (673 K). The effect of different ribs geometries with rib height to hydraulic diameter ratio (e/Dh=0.1364) and rib-rib spacing (pitch) to rib height ratio (p/e=10) in a rectangular channel of 0.5 m long , 57×27 mm internal cross section and 1.5 mm thickness was simulated. The experimental part, a rig was constructed to simulate conditions in an air cooled turbine blade. The operational conditions are: inlet coolant air temperature is (300 K), The surrounding constant hot air temperatures was (673K). The considered case with ribs was compared with a smooth channel (channel without ribs) at the same operational conditions. The channel with ribs was found to have higher thermal performance than the smooth ones: the percent increase in Nusselt number was (101%). The additional work involves coating the case with ribs by composite nanomaterials which is includes Tic nanoparticles and thermal polymer (6 wt. %) this composite enhances the Nusselt number by 170.6%.