The　blade　tip　region　encounters　high　thermal　loads　because　of　the　hot　gas　leakage　flows,　and　it　must　therefore　be　cooled　to　ensure　a　long　durability　and　safe　operation.　A　common　way　to　cool　a　blade　tip　is　to　design　serpentine　passages　with　180-deg　turn　under　the　blade　tip-cap　inside　the　turbine　blade.　Improved　internal　convective　cooling　is　therefore　required　to　increase　the　blade　tip　lifetime.　Dimples　and　protrusions　are　well　recognized　as　effective　devices　to　augment　heat　transfer　in　various　applications.　In　this　paper,　enhanced　heat　transfer　of　an　internal　blade　tip-wall　has　been　predicted　numerically.　The　computational　models　consist　of　a　two-pass　channel　with　180-　deg　turn　and　arrays　of　hemispherical　dimples　or　protrusions　internally　mounted　on　the　tip-wall.　Inlet　Reynolds　numbers　are　in　the　range　of　100,000　to　600,000.　The　computations　are　three　dimensional,　steady,　incompressible　and　non-rotating.　The　overall　performance　of　the　two-pass　channels　is　also　evaluated.　It　is　found　that　due　to　the　combination　of　turning　impingement　and　protrusion　crossflow　or　dimple　advection,　the　heat　transfer　coefficient　of　the　augmented　tip　is　a　factor　of　2.0　higher　than　that　of　a　smooth　tip.　This　augmentation　is　achieved　at　the　cost　of　a　penalty　of　pressure　drop　by　around　5%.　By　comparing　the　present　dimples　or　protrusions　performance　with　others　in　previous　works,　it　is　found　that　the　augmented-tips　show　the　best　performance,　and　the　dimpled　or　protruded　tips　are　superior　to　those　pin-finned　tips　when　the　active　area　enhancement　is　excluded.　It　is　suggested　that　dimples　and　protrusions　can　be　used　to　enhance　blade　tip　heat　transfer　and　hence　improve　blade　tip　cooling.　Copyright　©　2010　by　ASME.