Entity

Time filter

Source Type


Broszat D.,MTU Aerospace Engines GmbH | Kennepohl F.,MTU Aerospace Engines GmbH | Tapken U.,German Aerospace Center | Moser M.,University of Graz | And 2 more authors.
16th AIAA/CEAS Aeroacoustics Conference (31st AIAA Aeroacoustics Conference) | Year: 2010

Within the scope of last year's paper, the general setup of an acoustic turbine noise test facility at the Graz University of Technology has been described. This test rig has been used in several test campaigns studying the acoustic interaction of relatively rotating blade rows. In addition, the aerodynamic and acoustic measurement positions and the corresponding analysis processes have been explained. Complementary to these experimental investigations, analytical as well as numerical computations of the tonal noise generation of this test rig have been carried out using two MTU in-house tools, a semi-empirical/analytical code and a Linearized Euler code (LEE). Whereas the first two measurement campaigns covered in last year's paper aimed mainly at the validation of these two prediction tools by a distance variation of the stator and rotor rows, the campaign dealt with in this paper investigates a geometric acoustic modification of the TEC vanes (TEC = Turbine Exit Case). In this specific case, the modification consists of a negative lean angle of the airfoils compared to the standard (reference) TEC. This 3d-design has resulted from a parametric variation of the lean angle in a reasonable range and been motivated by the aim of reducing the acoustic impact of the - in general cut-on - interaction of the last rotor and the TEC in a commercial aircraft engine. A comparison of the acoustic measurement data acquired by DLR and the acoustic predictions by the LEE tool shows, on the one hand, a very good agreement with respect to the achieved noise reduction at the blade ↔ TEC interaction, on the other hand, a promising noise reduction potential not only at the design point. © 2010 by MTU Aero Engines GmbH. Published by the American Institute of Aeronautics and Astronautics, Inc. Source


Lengani D.,University of Graz | Lengani D.,Institute for Thermal Turbomachinery and Machine Dynamics | Lengani D.,University of Genoa | Spataro R.,University of Graz | And 7 more authors.
Journal of Propulsion and Power | Year: 2015

This paper identifies and analyzes the propagation of aerodynamic deterministic stresses through a two-spool counter-rotating transonic facility representative of modern and future turbine aeroengine sections. The test setup consists of a high-pressure stage, a diffusing turning midturbine frame with turning struts, and a counter-rotating low-pressure rotor. The flowfield downstream of the high-pressure stage is strongly influenced by the stator-rotor interaction. Such a mechanism interacts again with the downstream turning midturbine frame leading to a vane- rotor-vane interaction, which affects the behavior of the low-pressure stage. The results presented were obtained using a fast-response aerodynamic pressure probe for unsteady measurements as well as three-dimensional unsteady Reynolds-averaged Navier-Stokes calculations. The work is presented in two parts. This first part focuses on the explanation of the flow physics that governs the convection of unsteady three-dimensional flow through the midturbine duct. Viscous and inviscid mechanisms are discussed as main drivers for the convection of wakes, secondary vortices, andshocks.The flowfieldin the duct is characterizedbythree superimposedeffects: 1)ductdiffusionandradialpressure gradient together with turning strut potential field, 2) rotor unsteady work source, and 3) vane/blade interaction phenomena. The understanding of these mechanisms will eventually help to control the unsteadiness content in future architectures where reduced engine component length will enhance the interaction effects. © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source


Lengani D.,University of Graz | Lengani D.,Institute for Thermal Turbomachinery and Machine Dynamics | Lengani D.,University of Genoa | Spataro R.,University of Graz | And 6 more authors.
Journal of Propulsion and Power | Year: 2015

This paper analyzes the propagation of the aerodynamic deterministic stresses through a two-spool counterrotating transonic turbine at Graz University of Technology. The test setup consists of a high-pressure stage, a diffusing midturbine frame with turning struts and a counter-rotating low-pressure rotor. The discussion of the data is carried out in this second part paper on the basis of spectral analysis. The theoretical framework for a double Fourier decomposition, in time and space, is introduced and discussed. The aim of the paper is the identification of the sources of deterministic stresses that propagate through the turbine.Afast-response aerodynamic pressure probe has been employed to provide time-resolved data downstream of the high-pressure rotor and of the turning strut. The fastresponse aerodynamic pressure probe measurements were acquired together with a reference signal (a laser vibrometer) downstream of the high-pressure rotor to identify different sources of deterministic fluctuations. The discussion is completed by fast-response pressure measurements on the strut surface and computational fluid dynamics computation to detail which deterministic stress related to the high-pressure stage propagates through the duct. The double Fourier decomposition shows that structures at the periodicity of the rotor blade number decay, whereas the unsteadiness at the outlet of the duct is the result of vane-rotor-vane interaction. © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source


Plesiutschnig E.,University of Graz | Valiant R.,University of Graz | Stofan G.,University of Graz | Sommitsch C.,University of Graz | And 3 more authors.
Praktische Metallographie/Practical Metallography | Year: 2015

Cracks were found in the roots of steam turbine blades of the third blade row (LA-2) of the low-pressure turbine during revision works in a coal-fired power plant. Metallographic examinations reveal pitting corrosion sites, branched cracks, and local plastic deformation at the root of the first load bearing flank radius. The fracture surface was analyzed using light microscopy and scanning electron microscopy (SEM). Finite element (FE) simulations were performed in order to qualitatively represent the stress peak positions on the blade root. © Carl Hanser Verlag, Munchen Pract. Source


Selic T.,Institute for Thermal Turbomachinery and Machine Dynamics | Marn A.,Institute for Thermal Turbomachinery and Machine Dynamics | Schonleitner F.,Institute for Thermal Turbomachinery and Machine Dynamics | Hoeger M.,MTU AG | And 2 more authors.
11th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2015 | Year: 2015

Within previous EU projects, possible modifications to the engine architecture have been investigated, that would allow for an optimized aerodynamic or acoustic design of the exit guide vanes (EGV) of the turbine exit casing (TEC). However, the engine weight should not be increased and the aerodynamic performance must be at least the same. In addition, the effect onto the aeroacoustic field downstream of the EGV needs to be considered. This paper compares two different EGV designs. The first design is an acoustically optimized EGV whereas the second EGV is optimized strictly for aerodynamics. The comparison of the two different EGV configurations is done for an operating condition similar to the engine operation point approach. The measurements were conducted in the subsonic test turbine facility (STTF) at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes, the low pressure turbine (LPT) stage, and the EGVs have been designed by MTU Aero Engines. The flow field of the two different designs is being compared, and the difference in aerodynamical losses is show using 5-Hole probes as well as static surface pressure tabs and oil flow visualisation. In addition, aeroacoustic investigations were performed using an array of 24 wall-flush mounted microphones was used to acquire the sound field in the exhaust duct. Source

Discover hidden collaborations