The　effect　of　pre-swirl　nozzle　angle　(theta)　on　the　flow　and　heat　transfer　characteristics　of　a　radial　pre-swirl　system　is　numerically　investigated　using　the　CFD　software　ANSYS-CFX.　In　this　paper,　six　pre-swirl　nozzle　angles　are　selected　to　study　the　flow　dynamics　of　the　radial　pre-swirl　system　in　terms　of　the　flow　structure,　the　nozzle　exit　flow　angle,　the　air　swirl　ratio　at　nozzles　outlet　and　receiver　holes　inlet,　the　total　pressure　loss　coefficient　in　the　nozzle　and　the　cavity,　the　discharge　coefficient　of　the　nozzles　and　receiver　holes　and　the　adiabatic　effectiveness.　It　is　shown　that　the　case　of　theta　=　20　degrees　exhibits　the　best　performance　in　adiabatic　effectiveness　and　total　pressure　loss　in　this　system,　while　the　case　of　theta　=　60　degrees　provides　a　maximum　in　discharge　coefficient　of　receiver　holes　that　is　slightly　higher　than　that　of　theta　=　20　degrees.　Comparatively,　the　case　of　theta　=　20　degrees　provides　the　best　performance　of　the　radial　pre-swirl　system.　In　addition,　the　effect　of　pre-swirl　nozzle　angle　on　the　heat　transfer　characteristics　is　also　presented.　Results　show　that　the　heat　transfer　on　the　rotor　disk　is　dominated　by　the　flow　structure　and　tangential　velocity　differential,　and　the　peak　in　heat　transfer　coefficient　can　be　observed　near　the　receiver　hole.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.