Thermomechanical Analysis and Optimization of an Advanced Sealing System for Turbofan Engines

Growing concerns over ecological impact and environmental sustainability, together with the increasing demand for reduced fuel consumption, have driven the aerospace industry to seek disruptive solutions for next-generation propulsion systems. In response to these challenges, Safran has launched a development program to introduce a new engine concept that departs from the conventional ducted turbofan configuration. Instead, it adopts an architecture with an unducted fan, known as an Open Fan. As part of this program, a wide range of technological innovations are being investigated across the entire propulsion system. One specific innovation is the focus of the present work. This study focuses on the development of an advanced non-contact sealing system, an innovative technology designed to separate thermally distinct zones within the turbine. Such a system prevents the degradation typically observed at the interface between rotating and stationary components in current sealing systems, which causes performance to deteriorate. However, the absence of contact requires strict assurance that undesired interactions will not occur during the engine’s operating cycle, as the components are subject to thermomechanical deformations induced by variable thermal and pressure loads. For this reason, particular emphasis has been placed on investigating the system's deformation behavior, assessing its magnitude and underlying causes, and identifying the most suitable mitigation strategies. To this end, the work first provides a technical background on aircraft engines and the turbine environment under consideration, as well as an overview of the current state of the art in gas sealing devices. Having defined the problem, a thermomechanical analysis of the entire system is presented to characterize the response of its components under operating conditions. Furthermore, a modal analysis was carried out on the stator part of the system. The system was examined with respect to criticalities that lead to undesirable configurations during operation. Finally, possible solutions were explored, including applying thermal barrier coatings to the rotor walls and developing a parametric optimization methodology. This led to the proposal of a suitable geometry for addressing the problem.