On the Influence of an Acoustically Optimized Turbine Exit Casing onto the Unsteady Flow Field Downstream of a Low Pressure Turbine Rotor

Loris Simonassi, Manuel Zenz, Stefan Zerobin, Thorsten Selic, Franz Heitmeir, Andreas Marn

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


Modern low pressure turbines (LPT) are designed in order to fulfil a various number of requirements such as high endurance, low noise, high efficiency, low weight and low fuel consumption. Regarding the reduction of the emitted noise,
different designs of low pressure turbine exit guide vanes (aerodynamically and/or acoustically optimized) of the turbine exit casing (TEC) were tested and their noise reduction capabilities and aerodynamic performance were evaluated. In particular, measurements of TEC-losses were performed and differences in the losses were reported.
Measurements were carried out in a one and a half stage subsonic turbine test facility at the engine relevant operating point approach. This work focuses on the study of the unsteady flow field downstream of an unshrouded low pressure turbine rotor. The influence on the upstream flow field of a TEC design including acoustically optimized vanes (Inverse cut-off TEC) is investigated and compared with a second TEC configuration without vanes (Vaneless TEC), by means of fast response aerodynamic pressure probe measurements. The second configuration served as a reference concerning the influence of TEGVs onto the upstream located LPT rotor. The interactions between the stator and rotor wakes, secondary flows and the turbine exit guide vanes potential effect are identified via modal decomposition according to the theory of Tyler and Sofrin. The main structures constituting the unsteady flow field are detected and the role of the major interaction effects in the loss generation mechanism and in the acoustic emission is analysed.
This study based on the modal analysis of the unsteady flow field offers new insight into the main interaction mechanisms and their importance in the assessment of the aerodynamic and aeroelastic performance of modern low pressure turbine exit casings.
Original languageEnglish
Title of host publicationASME Turbo Expo 2018
Subtitle of host publicationTurbomachinery Technical Conference and Exposition
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages12
Volume2A: Turbomachinery
ISBN (Print)978-0-7918-5099-2
Publication statusPublished - Jun 2018
EventASME Turbo Expo 2018 : Turbomachinery Technical Conference & Exhibition - Lillestrøm, Norway
Duration: 11 Jun 201815 Jun 2018


ConferenceASME Turbo Expo 2018

Fields of Expertise

  • Mobility & Production


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