Analysis tools for the unsteady interactions in a counter-rotating two-spool turbine rig

Lengani, Davide; Santner, Cornelia; Spataro, Rosario; Göttlich, Emil

doi:10.1016/j.expthermflusci.2012.05.010

Cited by 23 publications

(18 citation statements)

References 19 publications

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“…The present paper, which is divided in two parts, extends the analysis of the baseline TMTF configuration proposed by Lengani et al [19]. The purpose of this two part paper is a detailed discussion of the unsteady flow propagation within the duct.…”

mentioning

confidence: 71%

“…The absolute Mach number at the TMTF inlet of about 0.5 is representative of realistic duct inlet conditions of modern jet engines with a single-stage HP turbine at the cruise operating point. These are the same operating conditions and test setup of previous publications (Lengani et al [18,19]). …”

Section: A Facility Descriptionmentioning

confidence: 97%

“…Previously published results from this facility in different configurations (baseline TMTF in Lengani et al [18,19] and TMTF with splitter vanes in Spataro et al [20,21]) have focused their attention on the unsteadiness at the outlet of the LP stage. They have shown that angle and velocity fluctuations of the HP stage decay quickly in the front part of the diffusing duct.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

Lengani

Spataro

Paradiso

et al. 2015

Journal of Propulsion and Power

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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 vanerotor-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, and shocks. The flowfield in the duct is characterized by three superimposed effects: 1) duct diffusion and radial pressure 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.

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mentioning

confidence: 71%

Section: A Facility Descriptionmentioning

confidence: 97%

mentioning

confidence: 99%

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Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

Lengani

Spataro

Paradiso

et al. 2015

Journal of Propulsion and Power

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“…Each revolution is divided into a fixed number of samples in order to correct small rotational speed variations of the rotor shaft [9]. The average of the samples at the same phase gives the phase averaged values.…”

Section: Phase Averaging and Adaptive Resamplingmentioning

confidence: 99%

Progress in Experimental Research of Turbine Aeroacoustics

Marn¹,

Faustmann²,

Selic

2016

Recent Progress in Some Aircraft Technologies

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Modifications on the intermediate turbine duct in order to reduce noise emissions by changing interaction frequencies and/or modes capable to propagate are presented. Also different turbine exit casings are described that are optimised to reduce interaction noise that is propagating through the engine and is one of the major noise sources during landing (operating point approach). The most promising modifications to reduce sound power levels are described. Depending on different modifications at specific operating points, the reduction of sound power level is between 5 dB and 10 dB, which is a significant reduction. However, some of these measures show an increase in aerodynamic losses. Therefore, a compromise has to be found between higher losses during a short duration (e.g. landing) and significant noise reduction. The chapter focuses on experimental results obtained in the test facilities of the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology.

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“…Therefore, phase averaging (Sharma et al (1985), Suder et al (1987), Hussain and Reynolds (1970)) and adaptive resampling (Lengani et al 2012) are performed on the measured sound pressure. After a classical Fast Fourier Transformation (FFT) determining the harmonic frequencies induced by each rotor, the processed sound pressure can be described in terms of acoustic cut-on modes propagating in the duct at a specific frequency.…”

Section: Acoustic Analysismentioning

confidence: 99%

Influence of Operational Geometry Changes on Turbine Acoustics

Bauinger¹,

Zerobin²,

Marn³

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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Due to the fact that noise emitted by aero engines became a very important issue especially during the last few years, acoustic measurements were carried out downstream of the lowpressure turbine in a two-stage two-spool test turbine. The aim of these analyses was to determine the influence of small geometry changes in the flow path of the rig under enginerelevant conditions, which usually occur during the operation of an engine. These geometry changes include steps in the flow path and different rotor tip gaps, both generated by a nonuniform warming of different parts of the engine. In order to evaluate the noise emissions, the outflow duct downstream of the second rotor was instrumented with an acoustic measurement section, which uses a circumferentially traversable microphone array located at the outer endwall. The acoustic field is characterized by azimuthal modes gained by traversing the microphone array over 360 degrees. Therefore, the spectra and emitted sound pressure levels are compared regarding different geometry changes.

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Analysis tools for the unsteady interactions in a counter-rotating two-spool turbine rig

Cited by 23 publications

References 19 publications

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

Progress in Experimental Research of Turbine Aeroacoustics

Influence of Operational Geometry Changes on Turbine Acoustics

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