The urgent requirement to minimise the environmental impact and costs associated with gas turbine operation has provided the incentive for OEMs to design engines capable of performing at ever-increasing cycle pressure ratios, turbine inlet temperatures and rotational speeds. An inevitable consequence of this trend is the requirement for safe operation of gas turbine components in an increasingly hostile environment. The severity of the environment in which critical gas turbine components operate is such that even quite modest improvements in cooling effectiveness can result in a disproportionate improvement in component life. To this end, the technique of pre-swirling the cooling air delivered to rotating components, in order to reduce its relative total temperature and thereby increase cooling effectiveness, is well established [1]. The present work describes a novel pre-swirl arrangement which overcomes significant shortcomings found in more traditional systems. The benefits of the system and its sensitivity have been explored using CFD techniques. This investigation has shown that there are likely to be substantial benefits of up to 20K in relative total temperature from adopting such a system. The use of CFD to explore such a design allows considerable insight to be gained into its characteristics before investing heavily in experimental demonstration, on an engine or rig.

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