Fine-Scale Turbulence Noise from Dual-Stream Jets

Tam, Christopher K. W.; Pastouchenko, Nikolai

doi:10.2514/1.18018

Cited by 14 publications

(7 citation statements)

References 37 publications

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“…Lilley's Equation formed the basis of the first jet noise prediction methodology [4] to be adopted by industry, and recent efforts have focused on improving models for the equivalent sources using data from Reynold's Averaged Navier-Stokes (RANS) calculations [5,6]. Approaches using equivalent source descriptions not based on the Lighthill/Lilley Analogies have also been developed [7,8]. The above models have proven very successful in predicting jet mixing noise at angles near 90°to the jet axis, but have generally been unsuccessful in predicting aft-radiated noise.…”

Section: Introductionmentioning

confidence: 99%

Wave-Packet Models for Large-Scale Mixing Noise

Reba¹,

Narayanan²,

Colonius

2010

International Journal of Aeroacoustics

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A wave-packet Ansatz is used to model jet noise generation by large-scale turbulence. In this approach, an equivalent source is defined based on the two-point space-time correlation of hydrodynamic pressure on a conical surface surrounding the jet plume. The surface is sufficiently near the turbulent flow region to be dominated by non-propagating hydrodynamic signatures of large-scale turbulent structures, yet sufficiently far that linear behavior can be assumed in extending the near-field pressure to the acoustic field. In the present study, a 78-microphone array was used to measure hydrodynamic pressure on the conical surface in order to identify parameters for the model and to validate the approach. Six microphones were distributed in the azimuthal direction at each of 13 axial locations spanning the first 8 jet diameters, allowing decomposition of azimuthal modes m = 0 and m = 1. We show that a source model based on a Gaussian correlation function provides a consistently good representation of the noise source attributed to large-scale structures. The results provide evidence that large-scale wave-like structures, known to dominate aft radiation at supersonic phase speeds, are also relevant at subsonic speeds.

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Section: Introductionmentioning

confidence: 99%

Wave-Packet Models for Large-Scale Mixing Noise

Reba¹,

Narayanan²,

Colonius

2010

International Journal of Aeroacoustics

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“…For the jet mean flow calculation, use is made of the oblique Cartesian coordinates method of Ref. [22]. Computation starts at the exit of the secondary nozzle and marches downstream to the tip of the plug nozzle.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…For this reason, boundary condition (17) for the variables † (ˆ p ,ˆ T ,ˆ u i ) cannot be implemented. As in previous work involving the computation of jet mean flow through parabolized equations 22 , a set of radiation/outgoing wave boundary conditions is used at the edge of the computation domain. This set of boundary conditions is derived by first finding an asymptotic solution (an approximate one if necessary) of the parabolized equations in the limit (y 2 +z 2 ) 1/2 is large.…”

Section: B Radiation or Outgoing Wave Boundary Conditionsmentioning

confidence: 99%

Installation Effects on the Flow and Noise of an Under-the-Wing Mounted Dual Stream Jet

Pastouchenko¹

2005

43rd AIAA Aerospace Sciences Meeting and Exhibit

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It is known experimentally that a jet mounted under a wing generates more noise than the same jet in isolation. The excess noise is referred to as installation noise. Installation noise is largely of aerodynamic origin. The principal mechanism is believed to be the impact of the downwash of the wing-flap on the jet flow. The downwash causes the jet to deflect downward and to distort laterally. This brings about an increase in turbulence in the jet. The increase in the level of turbulence, in turn, leads to the emission of additional noise. The modeling and computation of the downwash, the distorted jet flow and the excess noise radiation are the objectives of this investigation. It will be shown that calculated results at high frequencies compare well with experimental measurements.

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“…1 j x; tjy; 0 j y; dy d (18) wherẽ j x; tjy; @g x; tjy; @y j 1 @ṽ @y j g 4 x; tjy; (19) From the acoustics perspective, the primary interest is in the fourth pressurelike component of Eq. (18), which only involves the fourth component vector Green's function:…”

Section: Vector Green's Function Solution Formentioning

confidence: 99%

“…Unfortunately, the present approach still requires modeling nearly all of the unsteady flow in the initial mixing layers. But it is now believed that, whereas the sound produced by the larger-scale motion at the end of the potential core is relatively coherent, the relatively high-frequency sound produced by the small-scale mixing layer motions (as well as by the smaller-scale motion beyond the end of the potential core) tends to be much more random [19]. The latter should therefore be less sensitive to variations in retarded time than the former, which implies that it should also be less sensitive to the details of the source structure and, consequently, that relatively universal source models can be constructed.…”

mentioning

confidence: 97%

Hybrid Reynolds-Averaged Navier-Stokes/Large Eddy Simulation Approach for Predicting Jet Noise

Goldstein

2006

AIAA Journal

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Hybrid acoustic prediction methods have an important advantage over the current Reynolds-averaged NavierStokes based methods in that they only involve modeling of the relatively universal subscale motion and not the configuration-dependent larger-scale turbulence. Unfortunately, they are unable to account for the high-frequency sound generated by the turbulence in the initial mixing layers. This paper introduces an alternative approach that directly calculates the sound from a hybrid Reynolds-averaged Navier-Stokes/large eddy simulation flow model (which can resolve the steep gradients in the initial mixing layers near the nozzle lip) and adopts modeling techniques similar to those used in current Reynolds-averaged Navier-Stokes based noise prediction methods to determine the unknown sources in the equations for the remaining unresolved components of the sound field. The resulting prediction method would then be intermediate between the current noise prediction codes and previously proposed hybrid noise prediction methods. Nomenclature c = speed of sound D 0 = modified convective derivative D j = spatial derivative operator D Dt = convective derivative f = dummy variable g a = adjoint vector Green's function g = vector Green's function h = enthalpy h 0 = stagnation enthalpy K = component of linear Euler operator L = linear Euler operator p = pressurê p = component of pressure determined by base flow R = ideal gas constant R ij = residual stress tensor s = residual source vector T = absolute temperature, large time interval t = time u i = generalized residual velocity variable V = integration over all space v = velocity vector v i = component of v, i 1, 2, 3 x = position vector (usually associated with the observation point in the Green's function formulas) x i = Cartesian component of x, i 1, 2, 3 y = position vector of source y i = Cartesian component of y, i 1, 2, 3 jl = correlation of instantaneous propagator = specific heat ratio j = instantaneous propagator j = instantaneous propagator = five-dimensional Kronecker delta = Dirac delta function = separation vector in residual stress correlations ij = base flow stress tensor @ = generalized spatial derivative 00 = far-field pressure autocovariance = generalized residual pressure variable = densitỹ j = base flow stress tensor 0 j = generalized Reynolds stress tensor = source point time variablê = base flow quantity, filtered quantitỹ = base flow quantity, Favre-filtered quantity = time average hi = arbitrary spatial filter Superscripts 0 = residual quantity, dummy integration variable 00 = component of residual motion driven by residual stress, dummy integration variable, and fluctuating quantity

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Fine-Scale Turbulence Noise from Dual-Stream Jets

Cited by 14 publications

References 37 publications

Wave-Packet Models for Large-Scale Mixing Noise

Wave-Packet Models for Large-Scale Mixing Noise

Installation Effects on the Flow and Noise of an Under-the-Wing Mounted Dual Stream Jet

Hybrid Reynolds-Averaged Navier-Stokes/Large Eddy Simulation Approach for Predicting Jet Noise

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