Unsteady Interaction Between a Transonic Turbine Stage and Downstream Components

Davis, Roger L.; Yao, Jixian; Clark, John P.; Stetson, Gary M.; Alonso, Juan J.; Jameson, Antony; Haldeman, Charles W.; Dunn, Michael G.

doi:10.1155/s1023621x04000491

Cited by 20 publications

(5 citation statements)

References 11 publications

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“…Therefore, these frequencies represent deterministic fluctuations not related to the HP rotor rotation. To the knowledge of the authors, similar spectra, with peaks unrelated to the blade passing frequencies, were measured by Davis et al [5], Kielb et al [39], Southworth et al [40], and Green et al [41]. However, in these papers, there are no further comments or analyses about the source of these deterministic fluctuations.…”

Section: Resultsmentioning

confidence: 83%

“…For this reason, the peaks are marked in the figure as BPF HP − DS and BPF HP DS. The presence of traveling reflected waves has been documented in CFD investigations (e.g., Göttlich [4] and Davis et al [5]), performed in the HP rotor followed by a diffusing duct. However, in these previous investigations, it is not pointed out at which frequency (or combination of frequencies as observed here) they should occur or if they can travel downstream.…”

Section: Plane D: Tmtf Outletmentioning

confidence: 93%

“…However, as mentioned in part 1 [1], just a small percentage of these present the analysis of unsteady effects on a realistic configuration constituted by a transonic HP stage followed by an intermediate duct. Among these, an even lower fraction (e.g., Davis et al [5], Haldeman et al [6], and Lavagnoli et al [7]) discussed the data in the Fourier domain, taking particular notice of the frequencies propagating through the duct. For example, the analysis of Lavagnoli et al [7] highlighted that, along the strut surface, the dominant frequency is not always the blade passing frequency, but depending on the flow condition, the harmonics could be the frequencies with the highest amplitude.…”

Section: Introductionmentioning

confidence: 99%

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Unsteady Flow Evolution Through a Turning Midturbine Frame Part 2: Spectral Analysis

Lengani

Spataro

Peterleithner

et al. 2015

Journal of Propulsion and Power

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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. A fast-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. Nomenclature

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Section: Resultsmentioning

confidence: 83%

Section: Plane D: Tmtf Outletmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Unsteady Flow Evolution Through a Turning Midturbine Frame Part 2: Spectral Analysis

Lengani

Spataro

Peterleithner

et al. 2015

Journal of Propulsion and Power

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“…With the increase of rotor's tip clearance, the flow separation near the shroud reduced, but the ITD's overall loss increased. Davis et al 10 used numerical simulation to study the ITD's unsteady flow mechanism in a transonic turbine stage, and the numerical results were in good agreement with experiment. The results showed that the tip-leakage vortex still impacted the downstream LPT nozzle after a considerable axial distance.…”

Section: Introductionmentioning

confidence: 85%

Impact of turbulence intensity on the unsteady flow characteristics of the integrated aggressive inter-turbine duct

Liu

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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Aggressive inter-turbine duct (AITD) which has ultra-short axial length and ultra-large area ratio is widely applied in the modern turbofan engine to meet the demand of higher efficiency and better low pressure rotor dynamic characteristics. However, the adverse stream-wise pressure gradient in this duct is enhanced, and there are complicate upstream and downstream flow conditions. The flow field of the AITD and its downstream low pressure turbine is seriously deteriorated and prone to separate, especially in high-altitude cruise state. The integrated AITD which integrates the AITD with strut had been proved to can restrain the traditional AITD's three-dimensional flow separation. Besides, periodic wake can suppress the downstream blade suction surface's flow separation by “calmed region” effect according to former studies. The AITD of this research taken from a real engine utilizes integrated design and inherent upstream wake to suppress the flow separation of the AITD's end wall and low pressure turbine nozzle's suction surface correspondingly. In this article, the computational simulation method is used to quantify the impact of turbulence intensity ( T u) on the integrated AITD's unsteady flow characteristics, especially the separation and transition mechanism of low pressure turbine nozzle's suction surface boundary layer. Research shows that the impact of T u on the integrated AITD's flow property depends on the balance of T u's dual effect.

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“…There is a limited number of openly published works that analyze the impact of these unsteady effects on a downstream component in a realistic configuration (e.g., Miller et al [12,13], Davis et al [14], Haldeman et al [15], Göttlich et al [16], and Lavagnoli et al [17]). As observed in Miller et al [13] and in Göttlich et al [16], the first bend of the duct induces a radial pressure gradient on the flow, which makes the high-entropy fluid from the HP stage migrate to above 50% of the passage height.…”

mentioning

confidence: 99%

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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Unsteady Interaction Between a Transonic Turbine Stage and Downstream Components

Cited by 20 publications

References 11 publications

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 2: Spectral Analysis

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 2: Spectral Analysis

Impact of turbulence intensity on the unsteady flow characteristics of the integrated aggressive inter-turbine duct

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

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