Fan Noise Source Diagnostics Test - Vane Unsteady Pressure Results

Envia, Edmane

doi:10.2514/6.2002-2430

Cited by 40 publications

(29 citation statements)

References 1 publication

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“…Only modes m corresponding to specific linear combinations of the number of rotor blades B and of the number of stator vanes V are actually dominant in the source region. The common expression for these modes is as follows: (8) Each propagating mode spins at Ω m = sBΩ/m and the relationship between the BPF harmonics and the shaft harmonic order s is given by f BPF = |sBΩ|. More details on the modal decomposition in duct geometries are given by Sutliff.…”

Section: Modal Decompositionmentioning

confidence: 99%

“…12 and predicted by Eq. (8). Since the cut-off modes decay along the x-direction, the cut-on based reconstruction must have the same pattern as the band-filtered results.…”

Section: Duct Modes Analysis At Bpf Harmonic Ordersmentioning

confidence: 99%

“…Significant overall broadband levels are radiated to the far field due to motion and stretching of turbulent flow eddies 1,2 . In addition, generally intense tonal noise at specific frequencies as a result of rotor-stator interaction coupled with duct mode propagation in the nacelle is observed [2][3][4][5][6][7][8][9] . In the past decade, an effort towards the development of efficient acoustics liner aiming to reduce mainly the tonal part of the noise has been carried out.…”

Section: Introductionmentioning

confidence: 99%

“…A method allowing accurate modal decomposition as well as a good estimation of overall broadband content is therefore required. The Advance Noise Control Fan (ANCF) geometry of the NASA Glenn Research Center was developed in the early 1990's to provide detailed measurements of a turbo fan flow and corresponding noise produced by the ducted rotor/stator [2][3][4][5][6][7][8][9]12,13 . The measurements provide a better understanding of the correlation between the flow and the propagation inside the duct as well as the radiation to the far field.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Advanced Noise Control Fan Direct Aeroacoustics Predictions Using a Lattice-Boltzmann Method

Mann¹,

Pérot²,

Kim³

et al. 2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

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A Lattice-Boltzmann Method (LBM) based approach is used to perform transient, explicit and compressible CFD/CAA simulations on the Advanced Noise Control Fan (ANCF) configuration. The complete 3-D ducted rotor/stator model including all the geometrical details and the truly rotating rotor is simulated. Detailed near and far-field measurements conducted at the NASA Glenn research center are used to validate the simulation results. The measured and predicted sound pressure levels at the far-field microphones are compared and both show the presence of broadband noise and sharp peaks which frequencies depend on the number of rotor blades and the angular velocity of the rotor. The 3-D duct acoustics modes observed in experiments are also captured in the 3-D transient CFD/CAA calculation and detailed analyses of the results are presented. The main circumferential modes predicted from the number of rotor blades and stator vanes are recovered in both experimental and simulation modal decompositions. Nomenclature M = Mach number f k = k -th BPF harmonic order c b = Rotor blade chord s b = Rotor blade span Δx tip = Tip clearance c v = Stator vane chord d h,up = Upstream hub diameter d h,do = Downstream hub diameter p = Static pressure r = Radial coordinate θ = Azimuthal coordinate x = Axis coordinate t = Time m = Circumferential mode order n = Radial mode order k = x-axis eigenvalue κ = radial eigenvalue J m = Bessel function of the first kind and order m B = Number of fan blades V = Number of stator vanes s = Fan shaft harmonic Ω = Rotation frequency of the fan c 0 2 R 0 = Fan radius ρ 0 = Air density C i = Discrete collision component in the i -th direction c i = Discrete velocity component in the i -th direction f i = Particle distribution function in the i -th direction T = Temperature τ = Relaxation time ν = Kinematic viscosity ∆t = Numerical time step

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Section: Modal Decompositionmentioning

confidence: 99%

“…12 and predicted by Eq. (8). Since the cut-off modes decay along the x-direction, the cut-on based reconstruction must have the same pattern as the band-filtered results.…”

Section: Duct Modes Analysis At Bpf Harmonic Ordersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Advanced Noise Control Fan Direct Aeroacoustics Predictions Using a Lattice-Boltzmann Method

Mann¹,

Pérot²,

Kim³

et al. 2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

View full text Add to dashboard Cite

show abstract

“…Some works have highlighted the effects of the geometrical parameters such as the vane sweep or blade and vane counts for rotor/stator interaction noise. The most detailed investigation is the "Fan Noise Source Diagnostic Test" reported by NASA [2][3][4][5]. It deals with a stator with 54 radial vanes, a low-count stator with 26 radial vanes, and a low-noise stator with 26 swept vanes.…”

mentioning

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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New method to separate turbulence statistics of fan rotor wakes from background flow

Caldas

Meyer

2023

Exp Fluids

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The separation of turbulence parameters such as turbulence intensity and integral length scale of fan rotor wakes from background flow from unsteady velocity data is a challenge. The two processes are overlapped, and typically, very few samples of the data are taken inside the rotor wakes, making it hard to perform any spectral analysis. This work proposes a new time domain approach to separate the two processes by using two suitable data tapers. The unsteady velocity cyclic variance distribution is used as reference to establish the border between the blade wakes and the background flow. Results indicate an increase in wake turbulence levels and a slight increase in background turbulence levels with the increase in fan blade loading. The integral length scale of the rotor wakes did not change considerably among the different fan loading analyzed. This contrasts with the values observed for the background flow, which decreased with increasing of fan loading. The rotor wakes seem to be anisotropic, regardless of the fan operating point. Graphical abstract

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Fan Noise Source Diagnostics Test - Vane Unsteady Pressure Results

Cited by 40 publications

References 1 publication

Advanced Noise Control Fan Direct Aeroacoustics Predictions Using a Lattice-Boltzmann Method

Advanced Noise Control Fan Direct Aeroacoustics Predictions Using a Lattice-Boltzmann Method

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

New method to separate turbulence statistics of fan rotor wakes from background flow

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