Session: 22-04 Turbine Aerodynamic Excitation and Damping

Paper Number: 129134

129134 - Validation of a Methodology to Assess the Flutter Limit Cycle Oscillation Amplitude of Low-Pressure Turbine Bladed-Disks - Part II: Shaft Speed Effects 

The effect of the operating conditions on the vibration amplitude trends of an isolated low-pressure turbine rotor is described. The study utilizes an analytical model correlating the aerodynamic and dry-friction work introduced in Part I of the paper. In this second part, the analysis has been extended to incorporate the influence of rotational shaft speed. The force distribution and the penetration length of the fir-tree contact surfaces are key parameters within the heuristic micro-slip model used to characterize the friction forces. These parameters change with rotational speed, consequently influencing the dry-friction work involved in the process. The model is completed with numerical simulations to compute the aerodynamic damping and it is compared against experimental data gathered from the campaign detailed in Part I. The results demonstrate a significant impact of rotational speed on flutter vibration amplitude. It has been observed that the vibration amplitude reaches its peak value in proximity to the on-design conditions. The analytical model is able to correctly capture this specific characteristic of the system response. Furthermore, it shows that this behaviour is mainly related to the variation of the mechanical work parameters, the increment in the normal forces at the attachment and the change within the microslip friction regime.

Presenting Author: Salvador Rodríguez-Blanco Universidad Politécnica de Madrid

Presenting Author Biography: Salvador Rodríguez completed his Bachelor's and also his Master's Degree in Aeronautical Engineering at Universidad Politécnica de Madrid (UPM) in 2015 and 2017 respectively. He finished also in 2017 a Master in Computational Fluid Dynamics at Cranfield University. After one year working as a FEM engineer in the automotive industry, he came back to UPM in November 2018 as a PhD student working in the European Project Advanced Research into Aeromechanical Solutions (ARIAS). He finished his PhD in 2023 and currently, he is working as an assistant professor of the Applied Mathematics Department at UPM and is part of the turbomachinery research group.

Authors:

Alvaro Escudero Universidad Politécnica de Madrid
Salvador Rodríguez-Blanco Universidad Politécnica de Madrid
Roque Corral Universidad Politécnica de Madrid