Jet noise amplification - A practically important problem

Deneuville, P. M.; Jacques, Jean

doi:10.2514/6.1977-1368

Cited by 18 publications

(6 citation statements)

References 1 publication

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“…The individual components have been studied in laboratories, and corresponding models have been developed and tested over several decades. However, when these models are used to calculate the total noise from several components, including the jet noise, they often significantly underpredict the broadband jet noise from an actual jet engine [18][19][20][21]]. Understanding of this perplexing issue has challenged researchers for several decades.…”

Section: Objectives Of Jet Controlmentioning

confidence: 99%

High-Speed and High-Reynolds-Number Jet Control Using Localized Arc Filament Plasma Actuators

Samimy

Kearney-Fischer

Kim

et al. 2012

Journal of Propulsion and Power

102

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A class of plasma actuators called localized arc filament plasma actuators for high-speed and high-Reynoldsnumber flow and acoustic control has been developed at the Gas Dynamics and Turbulence Laboratory. Over the past several years, these high-bandwidth (0 to 200 kHz) and individually controlled actuators have been used successfully to excite the jet shear layer, jet column, and azimuthal instabilities in high subsonic and supersonic jets. The focus of this paper is to provide detailed information and sample results highlighting the capabilities and potential of the actuators and the control technique for mixing enhancement, noise mitigation, and flow and acoustic diagnostics. The jet, using three different nozzles, is operated over a large range of jet Mach numbers (0.9 to 1.65), stagnation temperature ratios (up to 2.5), and Reynolds numbers (0:2 10 6 to 1:65 10 6 ). Over this space of operating conditions, the jet is found to respond to control with a large range of forcing Strouhal numbers and azimuthal modes. The results reveal that the jet flowfield and acoustic far field can be dramatically altered, providing a powerful control tool in these practical high-speed and high-Reynolds-number jets.

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Section: Objectives Of Jet Controlmentioning

confidence: 99%

High-Speed and High-Reynolds-Number Jet Control Using Localized Arc Filament Plasma Actuators

Samimy

Kearney-Fischer

Kim

et al. 2012

Journal of Propulsion and Power

102

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“…The components have been separately studied in laboratories and corresponding models have been developed and tested over several decades. However, the laboratory and computational models of jet noise often significantly underpredict the broadband jet noise from an actual jet engine (Deneuville & Jacques 1977;Moore 1977a;Lu 1983;Tanna & Ahuja 1985). This perplexing issue has challenged researchers for several decades.…”

Section: Introductionmentioning

confidence: 99%

Acoustic and flow fields of an excited high Reynolds number axisymmetric supersonic jet

et al. 2010

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An axisymmetric perfectly expanded Mach 1.3 jet, with a Reynolds number based on the nozzle exit diameter (ReD) of 1.1 × 106 and turbulent boundary layer at the nozzle exit, was excited using localized arc filament plasma actuators over a wide range of forcing Strouhal numbers (StDF). Eight actuators distributed azimuthally were used to excite azimuthal modes m = 0–3. Far-field acoustic, flow velocity and irrotational near-field pressure were probed with a three-fold objective: (i) to investigate the broadband far-field noise amplification reported in the literature at lower speeds and ReD using excitation of m = 0 at low StDF; (ii) to explore broadband far-field noise suppression using excitation of m = 3 at higher StDF; and (iii) to shed some light on the connection between the flow field and the far-field noise. The broadband far-field noise amplification observed is not as extensive in amplitude or frequency range, but still sufficiently large to be of concern in practical applications. Broadband far-field noise suppression of 4–5 dB at 30° polar angle peak frequency, resulting in approximately 2 dB attenuation in the overall sound pressure level, is achieved with excitation of m = 3 at StDF ~ 0.9. Some of the noteworthy observations and inferences are (a) there is a strong correlation between the far-field broadband noise amplification and the turbulence amplification; (b) far-field noise suppression is achieved when the jet is forced with the maximum jet initial growth rate frequency thus limiting significant dynamics of structures to a shorter region close to the nozzle exit; (c) structure breakdown and dynamic interaction seem to be the dominant source of noise; and (d) coherent structures dominate the forced jet over a wide range of StDF (up to ~ 1.31) with the largest and most organized structures observed around the jet preferred mode StDF.

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“…Equation (14) may be rewritten as The last equality of Eqs. (15) and (16) (16) is the fully expanded jet Mach number.…”

Section: Imperfectly Expanded Supersonic Jetsmentioning

confidence: 99%

Dimensional Analysis of Jet Noise Data

Tam

2006

AIAA Journal

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A formula for scaling laboratory model jet-noise data to that of a full-size jet engine is established. This is done by dimensional analysis and the Buckingham Π theorem. It is well known that the noise intensity radiated by a jet varies as a high power of its velocity. This power-law dependence is supported by theory and experiment. The most famous power law is the Lighthill U 8 law. In this work, a dimensionless form of the power law is sought and developed. Through the use of this nondimensional power law, a "hot-jet" limit is found at high jet temperature. In the hot-jet limit, the velocity exponent and the proportionality constant of the power law are insensitive to further increase in jet temperature. This is a somewhat surprising result. Experimentally, it has been observed that seasonal temperature variation can lead to a 1.5-to 2.0-dB change in jet noise intensity. Here, environmental effects on jet noise such as seasonal and altitude variations are studied through results established by dimensional analysis. Finally, a way to scale jet mixing noise from perfectly expanded jets to shock-containing jets is proposed. Nomenclature a j = speed of sound of fully expanded jet a ∞ = ambient sound speed c p = specific heat at constant pressure D = nozzle exit diameter D j = fully expanded jet diameter f = frequency I = noise intensity L = fundamental dimension of length M = fundamental dimension of mass M d = nozzle design Mach number M j = fully expanded jet Mach number p e = pressure at nozzle exit p j = fully expanded pressure of jet p ∞ = ambient pressure R = gas constant Re = Reynolds number r, θ, φ = spherical polar coordinates S = power spectral density T = fundamental dimension of time T j = fully expanded jet temperature T r = reservoir temperature of jet T ∞ = ambient temperature γ = ratio of specific heats ν = kinematic viscosity ρ j = fully expanded gas density of jet ρ ∞ = ambient gas density Subscript e = variable at the nozzle exit

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Jet noise amplification - A practically important problem

Cited by 18 publications

References 1 publication

High-Speed and High-Reynolds-Number Jet Control Using Localized Arc Filament Plasma Actuators

High-Speed and High-Reynolds-Number Jet Control Using Localized Arc Filament Plasma Actuators

Acoustic and flow fields of an excited high Reynolds number axisymmetric supersonic jet

Dimensional Analysis of Jet Noise Data

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