Performance evaluation of a transpiration-cooled gas turbine for different coolants and permissible blade temperatures considering the effect of radiation

Abstract

Successful gas turbine technology is based significantly upon the introduction of new blade materials with increased permissible temperature for gas turbine blades and/or the use of efficient means and methods of turbine blade cooling in order to achieve the highest possible turbine inlet temperature. The gas turbine blade cooling models found in literature indicate that the effect of radiation from elevated temperature gases is generally not considered. However, the radiative heat transfer always occurs owing to the presence of mainly carbon dioxide and water vapour in the combustion products. The present paper deals with the comparative study of transpiration-cooled gas turbine cycle performance with and without taking radiation effect for different coolants and permissible blade temperature. The thermodynamic evaluation shows that, with consideration of the radiation effect, the theoretical coolant requirement increases so as to be close to the actual requirement and hence the cycle performance is affected accordingly. The transpiration-cooled gas turbine cycle performance parameter variations are presented to exemplify the role of cooling technology, cooling means, and material development, taking the radiation effect into account.