On the use of a uniformly valid analytical cascade response function for fan broadband noise predictions

Posson, Hélène; Moreau, Stéphane; Roger, Michel

doi:10.1016/j.jsv.2010.03.009

Cited by 60 publications

(45 citation statements)

References 45 publications

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“…The model is quoted below as a quasi-3-D annular model. It resorts to a strip-theory approach [18,22]. Each radial strip of the true blade row is unwrapped and assimilated to a rectilinear cascade having the local geometrical parameters.…”

Section: Broadband Noise Modelmentioning

confidence: 99%

Experimental Validation of a Cascade Response Function for Fan Broadband Noise Predictions

Posson

Roger

2011

AIAA Journal

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The present paper is aimed at assessing an analytical prediction model for the broadband noise produced by the impingement of turbulence on a cascade, using a dedicated experiment. The model is a strip-theory approach based on a previously published formulation of the unsteady blade loading for a rectilinear cascade. The experimental setup is made of a single stationary cascade of vanes mounted downstream of a turbulence grid in an annular duct, at the exit of an open-jet anechoic wind tunnel. The statistical parameters of the turbulence measured with hot-wire anemometry are used as input data in the model. The in-duct predicted downstream acoustic power is compared with the measured power obtained from the far-field acoustic pressure. Measured and predicted variations of the acoustic power with the number of vanes of the cascade and with the turbulence intensity are found to be in good agreement. It is concluded that the analytical approach succeeds in highlighting three-dimensional effects and is promising for further comparisons in more complex annular configurations. = squared norm of the duct eigenfunction E m; = microphone angle in the horizontal plane P containing the center of the exhaust section = turbulence integral length scale 0 = exponential correction factor of the turbulence spectrum 0 = fluid density = interblade phase angle uu ! = power spectral density of the streamwise velocity ww K; r = three-dimensional wave-number turbulence spectrum for the vane normal velocity component divided by u 2 rmŝ ' = sweep angle in the duct reference framê = stagger angle in the duct reference frame m;= eigenvalue of the mode m;

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Section: Broadband Noise Modelmentioning

confidence: 99%

Experimental Validation of a Cascade Response Function for Fan Broadband Noise Predictions

Posson

Roger

2011

AIAA Journal

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“…For instance, the model from Ventres et al [7], updated by Meyer and Envia [8] and by Nallasamy and Envia [9], deals with a two-dimensional (2-D) vortical excitation (no radial wave number) impinging on a vane cascade. Recently, Posson et al [10,11] proposed a model for rotor-stator interaction considering skewed (3-D) gusts and a 3-D analytical cascade response. Whereas this model has only been used for fan broadband noise applications [12], the current study focuses on the evaluation of this model for fan tonal noise prediction.…”

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confidence: 99%

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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“…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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On the use of a uniformly valid analytical cascade response function for fan broadband noise predictions

Cited by 60 publications

References 45 publications

Experimental Validation of a Cascade Response Function for Fan Broadband Noise Predictions

Experimental Validation of a Cascade Response Function for Fan Broadband Noise Predictions

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

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

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