In order to maximize their efficiency, modern aircraft engines feature reduced nominal clearances between rotating (such as bladed disks) and static (casing) components. As a consequence, structural contacts between these components are now more likely to occur and must be accounted for as early as in the design stage of the engine. To this day, there exists no relevant criterion to discriminate contacting components, such as blades, according to their sensitivity to contact events. In a recent study, it was found that a redesigned blade, featuring significant improvements with respect to its vibratory response following structural contacts, essentially differed from the original design with respect to its clearance consumption — a quantity that characterizes the evolution of blade/casing clearance as the blade vibrates over its first free-vibration modes. From this observation, it was decided to carry out a thorough investigation on the possible relation between clearance consumption and the nonlinear vibratory response following structural contacts. This paper presents an automated structural optimization procedure of a blade design using an objective-function related to the blade’s clearance consumption. Thus, optimized blades feature a lower clearance consumption. By means of an in-house numerical tool dedicated to the simulation of structural contact events with a surrounding casing, it is found that optimized blades feature lower amplitudes of vibration following contacts in comparison with the original blades. Overall, it is evidenced that the blade sensitivity to contact has been lowered as certain critical speeds vanish for the optimized profile. The current paper aims at establishing a proof-of-concept and thus only considers structural aspects. Aerodynamic considerations that are key for designing efficient blades are purposely left aside in order to focus on the feasibility of blade dynamics optimization.

This content is only available via PDF.
You do not currently have access to this content.