Prediction of aerodynamic sound from circular rods via spanwise statistical modelling

Casalino, Damiano; Jacob, Marc C.

doi:10.1016/s0022-460x(02)01136-7

Cited by 85 publications

(86 citation statements)

References 21 publications

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“…In order to use the two-dimensional near-field flow data, a "correlation length" method is adopted [34], similar to the statistical model used in Refs. [44][45][46]. This method assumes that the vortex shedding is perfectly correlated over a certain length of the cylinder in the spanwise direction.…”

Section: Methodsmentioning

confidence: 99%

Tandem cylinder aerodynamic sound control using porous coating

Liu

Azarpeyvand

Wei

et al. 2015

Journal of Sound and Vibration

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a b s t r a c tThis study is concerned with the application of porous coatings as a passive flow control method for reducing the aerodynamic sound from tandem cylinders. The aim here is to perform a parametric proof-of-concept study to investigate the effectiveness of porous treatment on bare tandem cylinders to control and regularize the vortex shedding and flow within the gap region between the two bluff bodies, and thereby control the aerodynamic sound generation mechanism. The aerodynamic simulations are performed using 2D transient RANS approach with k À ω turbulence model, and the acoustic computations are carried out using the standard Ffowcs Williams-Hawkings (FW-H) acoustic analogy. Numerical flow and acoustic results are presented for bare tandem cylinders and porous-covered cylinders, with different porosities and thicknesses. Experimental flow and acoustic data are also provided for comparison. Results show that the proper use of porous coatings can lead to stabilization of the vortex shedding within the gap region, reduction of the vortex shedding interaction with the downstream body, and therefore the generation of tonal and broadband noise. It has also been observed that the magnitude and the frequency of the primary tone reduce significantly as a result of the flow regularization. The proposed passive flow-induced noise and vibration control method can potentially be used for other problems involving flow interaction with bluff bodies.

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Section: Methodsmentioning

confidence: 99%

Tandem cylinder aerodynamic sound control using porous coating

Liu

Azarpeyvand

Wei

et al. 2015

Journal of Sound and Vibration

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“…Harmonic peaks have also been commonly observed for isolated cylinders. 13 Unsteady surface pressure data were obtained from Endevco transducers. The data from both a spanwise row and a 45…”

Section: Methodsmentioning

confidence: 99%

“…One could use approximate techniques 23 to account for different span and correlation lengths, but these formulas are only valid in the far-field, and the experimental microphone locations do not meet this criteria. Casalino and Jacob 13 have developed a statistical spanwise model that can be used with an FW-H solver to predict the noise even in the near-field. However, many problems of interest do not have a homogeneous direction, and we wished to assess whether a reasonable noise prediction can be obtained with the limited data records typical of CFD calculations.…”

Section: Ivd Acoustic Radiationmentioning

confidence: 99%

Tandem Cylinder Noise Predictions

Lockard

Khorrami

Choudhari

et al. 2007

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

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In an effort to better understand landing-gear noise sources, we have been examining a simplified configuration that still maintains some of the salient features of landing-gear flow fields. In particular, tandem cylinders have been studied because they model a variety of component level interactions. The present effort is directed at the case of two identical cylinders spatially separated in the streamwise direction by 3.7 diameters.Experimental measurements from the Basic Aerodynamic Research Tunnel (BART) and Quiet Flow Facility (QFF) at NASA Langley Research Center (LaRC) have provided steady surface pressures, detailed off-surface measurements of the flow field using Particle Image Velocimetry (PIV), hot-wire measurements in the wake of the rear cylinder, unsteady surface pressure data, and the radiated noise. The experiments were conducted at a Reynolds number of 166 × 10 5 based on the cylinder diameter. A trip was used on the upstream cylinder to insure a fully turbulent shedding process and simulate the effects of a high Reynolds number flow.The parallel computational effort uses the three-dimensional Navier-Stokes solver CFL3D with a hybrid, zonal turbulence model that turns off the turbulence production term everywhere except in a narrow ring surrounding solid surfaces. The current calculations further explore the influence of the grid resolution and spanwise extent on the flow and associated radiated noise. Extensive comparisons with the experimental data are used to assess the ability of the computations to simulate the details of the flow. The results show that the pressure fluctuations on the upstream cylinder, caused by vortex shedding, are smaller than those generated on the downstream cylinder by wake interaction. Consequently, the downstream cylinder dominates the noise radiation, producing an overall directivity pattern that is similar to that of an isolated cylinder. Only calculations based on the full length of the model span were able to capture the complete decay in the spanwise correlation, thereby producing reasonable noise radiation levels.

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“…Since the vortex shedding in flow over circular cylinder at Re = 22,000 is correlated over a distance of about 6.5D, the value of L c in current study is taken as 5D, following the procedure used by Doolan [32] and Casalino and Jacob [31]; here, N = 10 giving L s = 2.75D. The numerical and experimental acoustic power spectral densities are compared in Fig.…”

Section: Casementioning

confidence: 99%

“…Seo and Moon [30] develop a correction that allows the prediction of noise from long-span bodies using the numerical simulation of only a small span-wise portions of the body. Casalino and Jacob [31] use an ad-hoc statistical model to account for random phase differences along the span of cylinders with turbulent wakes. Also, Doolan [32] predicts spanwise-corrected noise using a statistical treatment on the sound source itself.…”

Section: Introductionmentioning

confidence: 99%