Extension of a Fan Tonal Noise Cascade Model for Camber Effects

Laborderie, Jerome de; Blandeau, Vincent P.; Nodé-Langlois, Thomas; Moreau, Stéphane

doi:10.2514/1.j053266

Cited by 15 publications

(10 citation statements)

References 22 publications

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“…For 3 BPF, these gaps go from 8 to 6 dB upstream and from 1 to 2 dB downstream (slight worsening). The comparisons at 1 BPF are mitigated, and a study performed in de Laborderie et al [39] suggests that vane camber effects play a major role, consistent with the findings of Evers and Peake [14], and should be considered at this frequency. Finally, the comparisons of acoustic powers confirm the analysis of the vane responses because the use of the 3-D corrected model allows improving the noise prediction compared to the numerical results.…”

Section: B Cme2 Compressor Stagesupporting

confidence: 69%

“…Concerning the analytical model, the flat plates representing the real stator vanes are staggered with their leading-edge metal angle. Indeed, the gust-cascade interaction noise is mainly controlled by the vane geometry parameters close to the leading edge [38,39]. The upwash velocity is extracted 1% of chord upstream of the stator and averaged in the rotor reference frame because it is shown in [36] that this method allows correctly representing the incident excitation, taking into account convection effects and steady stator potential effects.…”

Section: Cme2 Compressor-stage Unsteady Reynolds-averaged Navierstmentioning

confidence: 99%

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Evaluation of a Cascade-Based Acoustic Model for Fan Tonal Noise Prediction

Laborderie

Moreau

2014

AIAA Journal

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This study aims at evaluating an analytical model for the prediction of tonal fan noise created by the rotor-stator interaction. The methodology consists of comparing unsteady flow simulations with the cascade-based acoustic model to quantify the influence of some technological effects not included in the model. The simulations are performed with a dedicated turbomachinery flow solver Turb'Flow on a simplified stator vane cascade. They allow discussing the effects of both model assumptions of no vane thickness and inviscid flow on the predictions of the acoustic sources as well as on the modal acoustic powers radiated within the duct. The Kutta condition is found to be efficient to locally represent the viscosity effects, and the vane thickness tends to moderately modify the distributions of the sources and the amplitudes of the duct modes. Moreover, a three-dimensional decomposition of the aerodynamic excitation is proposed and coupled with the three-dimensional analytical cascade response. This fully three-dimensional acoustic model is evaluated by comparisons with an unsteady simulation of a realistic axial compressor stage. An improvement in the prediction of the acoustic sources and powers is clearly shown with respect to the previously used twodimensional version of the model. Nomenclature a = index of intervane channel acoustic mode B = number of rotor blades C = chord, m c 0 = speed of sound, m · s −1 d = nonoverlapping distance of the cascade, m E m;μ = duct radial function of the mode m; μ e = thickness, m f = force per surface unity, N · m −2 G = Green's function h = normal intervane distance, m j = index of the harmonic of the blade-passing frequency k = index of rectilinear cascade acoustic mode k r = spanwise aerodynamic wave number, m −1 M = Mach number m = order of azimuthal duct mode p = acoustic pressure, Pa p = order of the spanwise aerodynamic wave number S = surface, m 2 s= intervane distance, m T r = duct span, m t = time, s U xc = axial velocity in the rectilinear cascade reference frame, m · s −1 U xd = axial velocity in the duct reference frame, m · s −1 V = number of stator vaneŝ W j = azimuthal Fourier coefficient of w, m · s −1 W j;p = azimuthal and radial Fourier coefficient of w, m · s −1 w = upwash velocity (aerodynamic excitation), m · s −1 x, r, θ = cylindrical coordinates y = dimensionless wall distance ΔP = pressure jump across a flat plate (vane response), Pa μ = order of radial duct mode Π j = tonal acoustic power, W σ = intervane phase angle, rad χ m;μ = duct eigenvalue of the duct mode m; μ, m −1 χ s = vane stagger angle, rad Ω = rotational velocity, rad · s −1 Subscripts c = relative to the cascade reference frame d = relative to the duct reference frame H = relative to hub T = relative to tip

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Section: B Cme2 Compressor Stagesupporting

confidence: 69%

Section: Cme2 Compressor-stage Unsteady Reynolds-averaged Navierstmentioning

confidence: 99%

Evaluation of a Cascade-Based Acoustic Model for Fan Tonal Noise Prediction

Laborderie

Moreau

2014

AIAA Journal

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“…On the contrary, the modes due to the DRI mechanism present a peculiar evolution. As shown by Equation (10), the mode m is linked to the fluctuations on the fan blades at the (nB − m)-th multiple of the RF. Since the most important fluctuations of fan-blade loading correspond to the RF and its first harmonics (interaction with the distortion), the most important modes will be close to the rotor-locked mode m = nB = 36.…”

Section: Modal Analysismentioning

confidence: 99%

“…Hybrid methods stem from the acoustic analogy introduced by Lighthill [1] where source generation and noise propagation are separated steps. Acoustic sources can be extracted from a computational fluid dynamics (CFD) simulation or can be evaluated with analytical models, initially developed for isolated airfoils [2,3] and now extended to account for geometrical and cascade effects [4][5][6][7][8][9][10][11]. These sources can then be propagated either numerically by a computational aeroacoustics (CAA) simulation or analytically by an acoustic analogy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Distortion on Turbofan Tonal Noise at Cutback with Hybrid Methods

Daroukh

Moreau

Gourdain³

et al. 2017

IJTPP

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New ultra high bypass ratio architectures may significantly affect the fan tonal noise of future aircraft engines. Indeed, such a noise source is supposed to be dominated by the interaction of fan-blade wakes with outlet guide vanes. However, shorter nacelles in these engines are expected to trigger an important air-inlet distortion that can be responsible for new acoustic sources on the fan blades. Full annulus simulations based on the unsteady Reynolds-averaged Navier-Stokes equations are presently used to study this effect. Simulation results show that the air-inlet distortion has a main effect in the fan-tip region, leading to a strong variation of the fan-blade unsteady loading. It also significantly modifies the shape of the fan-blade wakes and, consequently, the unsteady loading of the outlet guide vanes. Acoustic predictions based on the extension of Goldstein's analogy to an annular duct in a uniform axial flow are presented and show that the fan sources notably contribute to the fan tonal noise. The air-inlet distortion is responsible for an increase of the noise radiated by both the fan and the outlet guide vane sources, leading to a global noise penalty of up to three decibels.

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“…Meanwhile, other studies have shown how geometrical details may influence the cascade acoustics response, particularly for the tonal noise component [21][22][23][24][25]. In a recent study, De Laborderie et al have investigated the camber effects to cascade acoustics response [25]. They extended the flat-plate-cascade acoustic model of Posson et al [26] by including the camber effects, and applied the model on a single-stage axial compressor.…”

Section: Introductionmentioning

confidence: 99%

A rod-linear cascade model for emulating rotor-stator interaction noise in turbofans: A numerical study

Teruna

Ragni

Avallone

et al. 2019

Aerospace Science and Technology

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a r t i c l e i n f o a b s t r a c tThis manuscript presents a rod-linear cascade model for emulating rotor-stator interaction noise. The model is intended as a test platform for studying noise mitigation techniques for a turbofan fan stage, while it also extends the classical rod-airfoil configuration by considering a row of blades based on realistic geometrical details. The rod-linear cascade model consists of a rod positioned upstream of a 7-blade linear cascade, such that the rod wake impinges onto the central blade. The rod is scaled to obtain a fundamental shedding frequency equal to the first blade passing frequency of the NASA-Glenn Source Diagnostics Test (SDT) fan stage at approach condition. The cascade blade profile is also based on the OGV of the SDT sampled at 90% of the radial span. Subsequently, numerical simulations are performed using lattice-Boltzmann Method on a computational setup comprised of a contraction and a test section enclosing the rod-linear cascade model. The integral length scales of the rod wake and the mean loading of the central blade have been found to be in good agreement with the trends observed in the SDT fan stage. The primary noise sources are localized at the central blade leading edge, although noise propagation to the far-field is influenced by additional diffraction by the other blades. Furthermore, the acoustic-blade row interaction causes intense pressure fluctuation within the inter-blade channels, including in those that are not directly affected by the rod wake.

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Extension of a Fan Tonal Noise Cascade Model for Camber Effects

Cited by 15 publications

References 22 publications

Evaluation of a Cascade-Based Acoustic Model for Fan Tonal Noise Prediction

Evaluation of a Cascade-Based Acoustic Model for Fan Tonal Noise Prediction

Effect of Distortion on Turbofan Tonal Noise at Cutback with Hybrid Methods

A rod-linear cascade model for emulating rotor-stator interaction noise in turbofans: A numerical study

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