Session: 22-04 Turbine Aerodynamic Excitation and Damping

Paper Number: 127475

127475 - A Computational Study of Temperature Driven Low Engine Order Forced Response in High Pressure Turbines 

This paper reports the results of computational studies of the effect of combustor exit temperature distortions, on Low Engine Order (LEO) forced response of a High Pressure Turbine (HPT). Forced response of this kind occurs at frequencies below the Stator Vane Passing Frequency (SVPF) and can be a major cause of High Cycle Fatigue (HCF) in turbines due to its tendency to excite fundamental modes of vibration at engine operating speeds. This paper investigates the mechanisms through which temperature distortions act as a forcing stimuli in HPT rotor rows, through measuring unsteady pressure and modal force magnitude recorded from full annulus unsteady simulations of the MT1 stage: a low temperature, unshrouded, HPT rig. Four key forcing mechanisms are identified: relative incidence angle variation, local static pressure fluctuations, shock position movement and passage vortex interaction, through which temperature acts as a forcer in HPT rotor rows. The dependence of temperature based forcing on distortion frequency and blade geometry is demonstrated and a key dependence of forced response on the modal content of the upstream temperature wave is revealed from which the paper presents a reduced domain method, suitable for use as an early-stage design tool for estimating temperature driven forced response.

Presenting Author: Alexander Trafford VUTC, Dept Mechanical Engineering, Imperial College London

Presenting Author Biography: Alex Trafford, PhD student at the Vibration University Technology Centre, Imperial College London.

Authors:

Alexander Trafford VUTC, Dept Mechanical Engineering, Imperial College London
Sina Stapelfeldt VUTC, Dept Mechanical Engineering