Open-source numerical strategy for the analysis and redesign of turbomachine blades accounting for nonlinear structural interactions

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Over the past decade, reducing the environmental footprint of turbomachines (such as aircraft engines and gas turbines) became a leading issue in both power and aerospace industries. While significant gains have already been made, promising avenues for further improvements require to mitigate hazardous nonlinear structural interactions related to contacts or friction, specifically for bladed components. This is a major roadblock for engineers due to the fact that blade design procedures are mostly driven by aerodynamic considerations. Nonlinear structural interactions are, at best, accounted for a posteriori, thus making modern blade design an inefficient trial-and-error process. When reported incidents call for a blade redesign, this lengthy design process translates into very high costs as power plants must be stopped or planes grounded. The large variety of nonlinear structural interactions involving turbomachine blades is related to the many mechanical interfaces on which contacts or friction may occur. For each of these interfaces, recent research has led to the development of predictive ad-hoc numerical methodologies. However, the use of distinct numerical paradigms and algorithms for each type of interface has compartmentalized these methodologies. In this context, the proposed research program aims at developing an open-source numerical strategy for the analysis and redesign of turbomachine blades, accounting for nonlinear structural interactions. First of all, a unified numerical framework will be proposed to carry out the first comprehensive multi-nonlinear analyses of turbomachine blades' vibration response, including both friction and structural contacts (respectively occurring at the blade/disk interface and at the blade-tip/casing interface). Frequency and time domain methodologies will be considered in a two-pronged verification approach. The second objective of the proposed research focuses on the development of blade-tip timing algorithms dedicated to nonlinear structural interactions. This will be essential to better understand the underlying physical phenomena associated to these interactions. It will be made possible through the development of a turbomachine digital twin for the generation of blade-tip timing data featuring nonlinear structural interactions. Finally, the last objective of the proposed research program relates to the redesign numerical strategy. It will notably rely on an original and open blade parameterization meeting both the needs of aerodynamicists and structural engineers. Results obtained from the two first research objectives will yield innovative guidelines, which will be used to design blades robust with respect to nonlinear structural interactions. This research program will have direct applications for the improvement of turbomachine blade design allowing for significant gains in terms of overall energy efficiency and maintenance cost.