LPT blade Sensitivity of the Boundary Condition at the interlocking and impact on flutter stability

Today a crucial objective of the aerospace industry is to realize lighter blades with a lower environmental impact. To pursue these objectives, it is necessary to find out innovative types of blades characterized by a new geometry feature and a lighter material. This thesis work is developed in collaboration with Avio Aero and its goal is to analyze aeroelastic issues of LPT blade, in particular the aim of this work is to show the impact of the different Boundary Conditions at the interlocking on the flutter stability. The entity of the contact at the interlocking must be studied, it is not possible to establish it in a deterministic way because during the blade’s service life causing flutter instability it could change. In this regard, three different contact configurations at the interlocking are analyzed in this work: TIGHT, RADIAL FREE and TIP FREE. Modal Analysis and Flutter Analysis are performed for each case to understand the impact on Modeshapes, Frequency and Flutter Stability. The Modal Analysis is performed by Finite Element Method with ANSYS APDL, Flutter Analysis instead by a CFD Finite Volume Method with a non-linearized flutter solver.In this work, all the process to perform a Flutter analysis through all the theoretical knowledges of all the steps is also explained. All the results and comparisons of the analysis performed between all the cases are shown.The results shows that TIP FREE configuration is more dangerous than the other two.