A simplified heat transfer model was extracted from the turbulated cooling holes located close to the periphery of the aerofoil of a turbine blade.The turbulators of the holes are ring ribs with rectangular cross section.By dimensional analysis

it is shown that the Nusselt number of the cooling holes was affected not only by Reynolds and Prandtl numbers

but also by the geometry of the turbulator

the distance between the hole and the outer surface of the blade

and the ratio of fluid conductivity to solid conductivity.A detailed numerical study shows that:(1) the ring ribs increase average Nusselt number

while the distance between the hole and the outer surface of the blade affects the local heat flux and Nusselt number distributing;(2) the Nusselt number monotonously increase with the increase of rib height to holes diameter ratio

e/d

but it also lead to rapid increase of friction coefficient;(3) by increasing Reynolds number and optimizing the ratio of rib pitch to rib height

p/e

Nusselt number of the cooling hole can be increased

the optimized value of p/e is about 10.