CFD Investigation of aeromechanic FORCING sensitivity for a generic transonic turbine
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Aeromechanic problems occur in various disciplines, the research here is focused on turbomachinery. Advanced design criteria and accurate prediction methods for aeromechanic problems such as forced response and flutter become increasingly important with the present demand in turbomachine engine development towards lighter, cheaper, more efficient and reliable turbomachines. The aeromechanic analysis made at a late stage in the design process plays a crucial role to avoid failures. The present work aims at getting a better understanding of the aerodynamic mechanisms in transonic turbine stages and further development of numerical methods for stator-rotor interaction predictions.
In this work standard industry tools are used for forced response computations for a one stage transonic high pressure turbine. Different configurations namely a tip shroud cavity, a hub cavity and external purge flow have been studied numerically to evaluate the influences on blade forcing predictions. CFD results are compared for all the cases with different features in both steady and unsteady state. Blade loading and integrated blade forcing are examined and physical interpretations of flow field features are given.
The investigation shows that including detailing features has a significant influence on the aerodynamic forcing. Leakage flow going through the tip shroud cavity is approximately 4.0% of the main passage flow. The first harmonic of rotor circumferential forcing is reduced by 19.8% when including the hub cavity. The tip shroud cavity feature tends to increase the unsteady aerodynamic forcing for the rotor blade despite of the slightly different operating conditions. The external purge flow has been proven to have a relative difference of 1.1% on the rotor blade forcing. The change in forcing is considered to arise from the interaction between the cavity flow and the main passage flow.
Place, publisher, year, edition, pages
2014. , 52 p.
CFD, Aerodynamics, Transonic Turbine, Aeromechanic Forcing, Turbomachinery, Forced Response, Cavity Flow
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-158019OAI: oai:DiVA.org:kth-158019DiVA: diva2:773451
2014-09-23, Remote, 14:37 (English)
Gezork, TobiasGutierrez Salas, MauricioGlodic, Nenad