Heat transfer in rotating two-pass channel with bleed holes on tip surface

Effusion flow from a blade tip region, not only protect the blade tip directly against hot gas but also influence the cooling performance of the internal cooling passage. The present study investigated the heat/mass transfer of a rotating two-passage rectangular duct using three different types of effusion hole arrays on the internal tip surface. The duct inlet was 80 mm × 16 mm, and the hydraulic diameter was 26.67 mm. The Reynolds number, which is based on the hydraulic diameter, was 10,000. The mass flow rate of the effusion flow was 10% of the total inlet mass flow. The naphthalene sublimation method was used to determine the local heat/mass transfer coefficient. The results indicated that effusion flow enhanced the heat transfer on the tip surface: they decreased the recirculation flow and counter-rotating flow in the turning region of the internal passage. The effusion holes enhanced the local heat transfer around holes due to local secondary flows such as tripping flows. The rotating channel had a different heat transfer distribution compared to the stationary channel due to Coriolis and centrifugal forces.