Abstract: Based on constructal theory, the construct of an elemental gas-turbine blade is optimized by taking minimum entransy dissipation rate as optimization objective. The optimal construct of the elemental gas-turbine blade is obtained. The results show that for the fixed total cross-sectional area and cavity faction of the elemental gas-turbine blade, there exists an optimal ratio of the cavity diameter to the thickness of the elemental blade which leads to the minimum dimensionless equivalent thermal resistance of the elemental blade; but there do not exist the optimal ratios of the cavity edge distance to the thickness, as well as the length to the thickness of the elemental blade which lead to the minimum dimensionless equivalent thermal resistance of the elemental blade. On the premise that the structural strength of the blade is allowed, the increase of the cavity fraction, the decrease of the cavity edge distance, and the slenderness of the elemental blade will help to improve the global heat transfer performance of the elemental blade. The optimal constructs of the elemental blade based on the minimizations of entransy dissipation rate and maximum temperature difference are different. The average heat transfer temperature difference of the elemental blade based on the minimization of entransy dissipation rate can be more effectively reduced compared with that based on the minimization of maximum temperature difference, and its global heat transfer performance is obviously improved. Moreover, the global heat transfer performance of the elemental blade can also be obviously improved by using the multi-scale constructal optimization of the cooling cavity of the elemental blade.

Key words: constructal theory;entransy dissipation rate;blade cooling;generalized thermodynamic optimization