TY - GEN

T1 - Optimization of intentional mistuning patterns for the mitigation of the effects of random mistuning

AU - Han, Yun

AU - Mignolet, Marc

PY - 2008

Y1 - 2008

N2 - This paper focuses on the optimization of intentional mistiming patterns for the reduction of the sensitivity of the forced response of bladed disks to random mistuning. Intentional mistiming is achieved here by using two different blade types (denoted as A and B) around the disk. It is thus desired to find the arrangement of these A and B blades (A/B pattern) that leads to the smallest 99th percentile of the amplitude of blade response in the presence of random mistuning. It is first demonstrated that there usually is a large number of local minima and further that the cost of a function evaluation is high. Accordingly, two novel, dedicated optimization algorithms are formulated and validated to address this specific problem. Both algorithms proceed in a two-step fashion. The first step, which consists of an optimization in a reduced space, leads to a series of good initial guesses. A local search from these initial guesses forms the second step of the methods. A detailed validation effort of this new procedure was next achieved on both a single-degree-of- freedom per blade model and a reduced order model of a blisk. In all validation cases, the two novel algorithms were found to converge to the global optimum or very close to it at a small computational cost. Finally, the results of this optimization efforts further demonstrate the value of intentional mistuning to increase the robustness of bladed disks to random mistuning.

AB - This paper focuses on the optimization of intentional mistiming patterns for the reduction of the sensitivity of the forced response of bladed disks to random mistuning. Intentional mistiming is achieved here by using two different blade types (denoted as A and B) around the disk. It is thus desired to find the arrangement of these A and B blades (A/B pattern) that leads to the smallest 99th percentile of the amplitude of blade response in the presence of random mistuning. It is first demonstrated that there usually is a large number of local minima and further that the cost of a function evaluation is high. Accordingly, two novel, dedicated optimization algorithms are formulated and validated to address this specific problem. Both algorithms proceed in a two-step fashion. The first step, which consists of an optimization in a reduced space, leads to a series of good initial guesses. A local search from these initial guesses forms the second step of the methods. A detailed validation effort of this new procedure was next achieved on both a single-degree-of- freedom per blade model and a reduced order model of a blisk. In all validation cases, the two novel algorithms were found to converge to the global optimum or very close to it at a small computational cost. Finally, the results of this optimization efforts further demonstrate the value of intentional mistuning to increase the robustness of bladed disks to random mistuning.

KW - Blade damping

KW - Blade vibration

KW - Bladed disk

KW - Damping optimization

KW - Intentional mistuning

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U2 - 10.1115/GT2008-51439

DO - 10.1115/GT2008-51439

M3 - Conference contribution

AN - SCOPUS:69949180054

SN - 9780791843154

T3 - Proceedings of the ASME Turbo Expo

SP - 601

EP - 609

BT - 2008 Proceedings of the ASME Turbo Expo

T2 - 2008 ASME Turbo Expo

Y2 - 9 June 2008 through 13 June 2008

ER -