1. Center for Aerospace Science and Technology, Instituto Superior Técnico, Lisbon 1049, Portugal
2. Fluid Mechanics Lab., Global Research Center, General Electric, Niskayuna, New York 12309
3. Department of Aeronautics, Massachusetts Institute of Technology, Cambridge, Masachussetts 02139
4. Turbomachinery Aerodynamics Lab, Global Research Center, General Electric, Niskayuna, New York 12309