Comparative evaluation of gas turbine power plant performance for different blade cooling means

Abstract

The thermodynamic performance of a gas turbine power plant has been compared for different means of blade cooling in this work. Seven schemes involving air and steam as coolants under open- and closed-loop cooling means have been studied. The closed-loop cooling includes only the internal convection cooling (ICC) technique, while the open-loop cooling schemes include the internal convection, film, and transpiration cooling means. Comparative evaluation shows that among all the cooling schemes considered, the open-loop steam ICC offers highest specific work and thus highest values of plant efficiency of about 50 per cent, whereas open-loop film steam cooling, transpiration air cooling, film air cooling, and internal convection air cooling have been found to yield lower values of plant efficiency in decreasing order. The specific work is higher for all open-loop steam cooling means due to steam injection into the hot gas stream of the turbine.