Session: 01-11 Modelling, Simulation and Validation III

Paper Number: 122913

122913 - Power Analysis of Wave Speed Coincidence Stability and the Effect of Asymmetry 

Wave speed coincidence is an interaction that can occur between a bladed-disc and a casing in turbomachines due to tip rub. This is of concern to engine manufacturers since synchronisation of casing and blade vibrations may lead to high amplitude vibration and potentially cause damage to the structure. New engine design features such as decreasing tip gaps and more axisymmetric casings can increase the likelihood of this phenomenon.

Analysis of wave speed coincidence requires that we treat both the bladed-disc and casing as flexible structures, and that we employ realistic contact models and rotational effects. Very few papers on the subject include all of these effects and hence their usefulness is limited for predicting the onset of wave speed coincidence in real scenarios.

This paper examines improvements in the numerical simulations to predict system behaviour more accurately. Additional features that significantly influence wave speed coincidence have been added such as the inclusion of an abradable liner commonly used in aircraft engine designs. However this also leads to increased computational cost which creates additional challenges in analysing multiple designs and operating conditions. This research explores the possibility of new methods, such as a new screening method with a power-based approach, that can quickly identify cases with high risks of wave speed coincidence. This provides significant improvement over current design screening methods for new engine designs.

Presenting Author: Chris Ma University of Nottingham

Presenting Author Biography: Currently a PhD research student, studying the wave speed coincidence phenomenon in gas turbines, at the University of Nottingham Gas Turbine and Transmissions Research Centre. Graduated in 2015 from Imperial College London with a 1st Class Hons MEng Degree in Aeronautical Engineering. Worked in Rolls-Royce plc mainly as a whole engine analyst within structural system design. More recent work focused on rotordynamics and other aircraft engine structural dynamics, including the current research into wave speed coincidence.

Authors:

Chris Ma University of Nottingham
Seamus Garvey University of Nottingham
Punithavathy Kamesh Rolls-Royce plc
Andrew Rix Rolls-Royce plc