Damping Mistuning Effects on the Amplification Factor and Statistical Investigation of Vane Packet

Abstract: A novel methodology to investigate statistically the effects of random damping mistuning in vane systems is presented. The rotating components if turbomachinery, which are called bladed disks or rotors, accelerate the mixture of gas and air. The stationary airfoils, also known as stators or vanes, convert the increased rotational kinetic energy into static pressure, redirecting the flow paths of the fluid. The excitation forces induced from the interactions between the fluid and the mechanical components act on the airfoils of the rotors and vanes. Rotors are designed to be cyclically symmetric, where all sectors carry identical structural properties. In practice, however, variations exist in structural properties among individual sectors due to a variety of reasons such as manufacturing tolerances, and operational wear. These blade-to-blade deviations are referred to as mistuning, and they affect the free vibrations and forced responses of bladed disk assemblies. It is known that while mistuning has a beneficial effect on flutter, mistuning can create a significant increase in the maximum response amplitudes experienced by a few blades. Thus, accurate predictions of mistuned forced responses and the effects of mistuning on forced response levels have been a major concern in the design of blade assemblies. This study presents a novel methodology to investigate the influence of damping variability from blade to blade in vane systems.