3D Laser Anemometry in a Rotating Cooling Channel

Abstract

The flow in rotating cooling passages of jet engine turbine rotors is considered. Contrary to thermal data which have been obtained by a lot of people, velocity field data are very few. Nevertheless, in order to validate Navier-Stokes calculations, these two types of data are necessary. In such a flow with complexe secondary structures, 3D laser anemometer is the most suitable tool but its implementation on this application was a challenge. Measurements were made first in static mode at Reynolds numbers of 5,000 and 25,000. The same model sections were then explored during rotation at a Reynolds number of 5,000 and a Rossby number of 0.33. Some results were obtained a Reynolds number of 25,000 and a Rossby numbers of 0.033 and 0.066. The distortion of the axial velocity profile resulting from the Coriolis acceleration appears clearly when comparing the results obtained in the sections of the centrifugal arm. In the transverse plane, the two other velocity components show the secondary flow structures with two contrarotating vortices. The results obtained in the centripetal arm show that the flow depends on the 180 deg straight-corner turn located upstream. These measurements confirm the assumptions made on the organisation of this type of flow, and the simulation results obtained at ONERA with the MATHILDA code and also by other teams who have published papers on the subject. The first results obtained during this experimental work demonstrate the validity of the 3D laser anemometry in such a case. They show also some insufficiencies due to an application deemed difficult.