Experimental Research on Heat Transfer Characteristics of Fractal Tree-Like Microchannel for Cooling Gas Turbine Blade

Following energy transport principle and fractal geometry theory, the fractal network fitted for the fluid flow transport in the blade internal passages was generated, and the fractal tree-like branching microchannel was designed as an internal cooling structure for turbine blade. In the experiment system of convection cooling for gas turbine internal microchannel, the effects of inlet Reynolds number and heating power on the Nusselt number, friction factor and enhancement heat transfer factor of air flow were investigated. The results reveal that as Reynolds number ranges from 194 to 19 400, the average Nusselt number of air increases by 148.5%, the friction factor decreases from 0.78 to 0.009 and the maximum value of enhancement heat transfer is obtained at inlet Reynolds number=17 300. When the heating power ranges from 10 W to 110 W, the average Nusselt number reduces by about 35.9%, the friction factor changes slightly and the best enhancement heat transfer factor is observed at P=10 W. The local Nusselt numbers of the first and second level microchannel are greatly promoted by the branching structure in combination with the conjugation heat transfer effects. In comparison of the first three levels microchannels, the heat transfer performance of the last level microchannel is more obviously affected by Reynolds number and heating power.