Periodic Reporting for period 1 - BC-Int (Contact-induced blade-casing interactions in aero-engine turbines - An integrated simulation framework for local and global nonlinearities)
Periodo di rendicontazione: 2022-10-01 al 2024-09-30
The project was aligned with the Strategic Research and Innovation Agenda (SRIA) developed by Advisory Council for Aviation R&I in Europe (ACARE), more specifically with the 3rd FLIGHTPATH 2050 goal, ‘Maintaining and extending industrial leadership’, contributing to streamlining systems design process able to address the complexity and decrease development costs. Its specific goal was to provide an accurate and efficient numerical tool to predict the critical engine configuration to avoid unforeseen and harmful interactions between rotating and static parts. This numerical tool enables the design of more efficient engines by decreasing flow leakage. To provide an accurate model, a geometrically nonlinear model of the rotating blades having interaction with the casing has to be considered. The analysis of such a model dealing simultaneously with both contact and geometric nonlinearities can be handled efficiently only using reduced-order models. So one main goal was to develop an accurate reduced model capable of predicting the nonlinear behavior of structure due to blade casing interaction. Experimental analysis was considered to validate the model and ensure its accuracy. Then this model has to be used to propose design guidelines by improving the understanding of the physical phenomena. In addition, reaching these technical goals ensures a considerable improvement in the skills of the researcher. Also, it provides new modeling and experimental capabilities in the portfolio of the host organization.
This project involves the development of Python code. This code predict the nonlinear vibration of a geometrically nonlinear structure with friction contact. The problem can be solved both in time and frequency domains. However, the time domain method (Newmark-Beta) provides both the transient and steady-state response at a higher computational cost, whereas the frequency domain analysis provides only the steady-state response via the harmonic balance method. Users can select the solution domain based on their requirments. A 2D contact element is used to caluculate contact forces due to the relative displacement of the components. To account for geometric nonlinearity, first, the Nonlinear Finite Element (NFE) formulation of a beam was employed to calculate the nonlinear elastic forces. This so-called intrusive method limits the solver to model the blade as a 2D beam. However, this NFE formulation (coded during the researcher's Ph.D.) enabled the accuracy evaluation of the developed reduced models. As a result, experimental analysis for validation is no longer required. Later, the nonintrusive methods were implemented allowing the commercial FE software to be used to simulate the 3D blade geometry, as well as very efficient computation of the nonlinear elastic forces as a function of the generalized coordinates.
First, the performance of the available reduced model capable of capturing both types of nonlinearities was studied particularly for a simplified model of blade casing interaction.
Then, the optimal approach for the project application was selected based on the primary study, and several novel modifications were proposed to increase the accuracy of this reduced model.
Finally, a novel methodology is proposed for capturing the nonlinear dynamics of structures undergoing both nonlinearities, which is relevant not only to simplified models but also to industrial applications.
The code developed based on these methodologies can be integrated with the optimization algorithms that aim to improve the reliability and efficiency of aero engines.
Commercialization is the key need to ensure further uptake of this code.
Then, the optimal approach for the project application was selected based on the primary study, and several novel modifications were proposed to increase the accuracy of this reduced model.
Finally, a novel methodology is proposed for capturing the nonlinear dynamics of structures undergoing both nonlinearities, which is relevant not only to simplified models but also to industrial applications.
The code developed based on these methodologies can be integrated with the optimization algorithms that aim to improve the reliability and efficiency of aero engines.
Commercialization is the key need to ensure further uptake of this code.