EXPERIMENTAL INVESTIGATION OF THE FLOWFIELD RESULTING FROM THE INTERACTION BETWEEN AN IMPINGING JET AND A ROTATING-DISK

The highly stressed blade attachment regions of high-temperature turbine disks can be cooled by fluid jets directed to impinge at or near the disk outer rim. With such a scheme the cooling effect can be both intense and localized. Earlier heat transfer studies suggest that the achieved cooling rates are closely related to the detailed flow structure in the region where the jet interacts with the disk wall boundary layer, where the velocity is maximum at the wall. The interaction is expected to be quite different from the usual situation of a jet in a crossflow, and the present study was conducted to document the details of the mean and fluctuating velocity fields in the interaction region. Tests were conducted in a specially fabricated chamber employing water as the test fluid, and the detailed structures of the turbulent velocity fields were measured by laser-Doppler velocimetric methods. With sufficient jet flow, the jet is found to penetrate very deeply into the wall boundary layer, with jet expansion against the direction of disk rotation observed even at the measurement locations closest to the disk surface.