Rear Flow Separation

CFD calculation also showed a tendency that the largest few disturbance occurs in the procedure associated with slight opening of MSV, in which the fan bypass jet remains not much diffused till rapidly matching the rear pressure near RBAVI. The flow separation at the hub wall must be also influenced by the wall shape, in particular, its slope towards downstream. Figure 7 compares the few patterns corresponding to CASE3 when the hub wall slope was modified to become fhttened. There is still a vortex structure in the center part, but the separation at the hub wall disappeared remarkably. Examining various cases for the static pressure distributions along the bypass duct axis, it was revealed that rather smooth tendency is obtainable for most of the cases, except CASE3 with the original hub wall slope. It seems CASE3 (FVABI narrowed) is rather

peculiar, that all the infliencing factors bring about a coupled effect upon the resulting ft>w pattern, so that more careful study is required.