Cagdas Kafali
(cxk50@po.cwru.edu)
and
Dario A. Gasparini,
Professor (dag6@po.cwru.edu)
Department of Civil
Engineering
Case Western Reserve University
Cleveland, OH 44106-7201
The
dynamic behavior of all rotor assemblies is very sensitive to small variations
in the structural dynamic characteristics (natural frequencies and mode shapes)
between individual blades caused by geometric imperfections on the blade
surface. Mechanical and aerodynamic coupling of blades is also sensitive to
geometric imperfections.
The
effects of geometric perturbations on torsional and flexural mode coupling of
an individual blade are examined. Mechanical coupling (through the disk)
between different blades is discussed.
A statistical approach is needed to analyze the coupling behavior of higher modes where the number of frequencies in a range is known but not the exact frequency locations. A finite element model (using ANSYS), which includes axial stiffening effect due to radial acceleration, is used for analysis.