An efficient disk design optimization process for limiting mistuned blade vibration and stress levels in turbine engine rotors

A design optimization process is presented for improving the structural performance of turbine engine rotors with respect to blade vibration response. A novel aspect of the methodology is that only the disk is changed, while the airfoil design is not altered. The disk geometry is optimized to ensure that blade stress levels are kept below a safe limit, as defined by a Goodman diagram, while also reducing weight. The effects of both rotation and small, random blade-to-blade structural differences (mistuning) on vibration and stress levels are considered. For computational efficiency, a two-part optimization approach is adopted. First, vibration power flow analysis of the tuned system is used to generate rough estimates of the system's sensitivity to mistuning. This accelerates each iteration of the optimization loop, but the resulting optimum satisfies the design goals only in an approximate sense. Second, starting with this revised design, a more accurate optimization is performed by running a Monte Carlo simulation for each iteration. This second part is more expensive, but relatively few iterations are needed to find a true opti-mum. The design process is validated for example finite element models of turbine engine rotors.