Seeding of helical modes in the initial region of an axisymmetric jet

Kusek, S. M.; Corke, Thomas; Reisenthel, Patrick

doi:10.1007/bf00215019

Cited by 26 publications

(15 citation statements)

References 11 publications

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“…2b). This Y pattern was also observed experimentally by Kusek et al 15 and numerically by Martin. 16 Under forcing with the m = §1 helical mode pair at Sr D =0.6, a two-lobed shape of the jet cross section was observed (not shown in this paper; refer to Cho 19 and Long and Petersen 17 ).…”

Section: A Forcing With Only a Helical Mode Pair (M = § § 1)supporting

confidence: 71%

Resonance in Axisymmetric Jet Under Controlled Helical, Fundamental, and Axisymmetric Subharmonic Forcing

2000

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An axisymmetric jet is forced with two helical fundamental waves of identical frequency spinning in the opposite directions and an additional axisymmetric subharmonic wave. The subharmonic component rapidly grows downstream from resonant interaction with the fundamental, signi cantly depending on the initial phase difference between the subharmonic and the fundamental. The variation of the subharmonic amplitude with the initial phase difference shows a cusplike shape. The ampli cation of the subharmonic results in a vortex pairing of helical modes. Furthermore, the azimuthal variation of the ampli cation induces an asymmetric jet cross section. When the initial subharmonic is imposed with an initial phase difference close to a critical value, the jet cross section evolves into a three-lobed shape. The lobes are generated by vortex pairing. Therefore, the conclusion is made that the initial phase difference between the fundamental and the subharmonic plays an important role in controlling the jet cross section. Nomenclaturea s = subharmonic amplitude at jet exit [(u 0 s / U e )j x = 0 ] D = jet diameter f = fundamental frequency m = azimuthal wave number p = sound pressure Re D = Reynolds number based on jet diameter (U e D/ m ) r = radial coordinate r 0.1 = radial position, where U / U c = 0.1 Sr D = Strouhal number based on jet diameter ( f D/ U e ) U = streamwise mean velocity u = streamwise velocity uctuation x = streamwise coordinate c = azimuthal angle h = momentum thickness: Z r0.1 0 U U c 1 ¡ U U c´d rḿ = kinematic viscosity u d = local phase difference between the fundamental and the subharmonic (u f ¡ 2u s ) u de = initial phase difference between the helical fundamental mode pair and the axisymmetric subharmonic measured at x / D =0, r/ D =0.25, and c = 0 deg (u fe ¡ 2u se ) u f = local phase of the fundamental wave u fe = initial phase of the helical fundamental wave [Eq. (1)] u h = local phase of the rst-harmonic wave u s = local phase of the subharmonic wave u se = initial phase of the axisymmetric subharmonic wave [Eq. (3)] Subscripts c = jet center e = jet exit Presented as Paper 98-0783 at . Member AIAA. f = fundamental h = harmonic m = maximum value s = subharmonic Superscript 0 = rms

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Section: A Forcing With Only a Helical Mode Pair (M = § § 1)supporting

confidence: 71%

Resonance in Axisymmetric Jet Under Controlled Helical, Fundamental, and Axisymmetric Subharmonic Forcing

2000

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“…In the seminal work of Crow and Champagne [13] that established the presence of large-scale structures in relatively high-Reynoldsnumber jets (Re D 10 5 ), the well-defined time base provided by periodic excitation was used to analyze the data from hot-wire anemometry and schlieren imaging. Subsequently, many investigators sought to understand the development, evolution, and interaction of these structures, both axisymmetric and helical, using phase-averaged imaging and measurements (e.g., [12,27,[30][31][32][33][34][35]). The implication of these discoveries in forced jets for the structure of unforced jets has been debated all along.…”

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

105

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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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“…Subsequently, many investigators sought to understand the development, evolution and interaction of such seeded structures, both axisymmetric and helical, using phase-averaged imaging and measurements [e.g. 12,23,[30][31][32][33][34][35]. The implication of these discoveries in forced jets for the structure of unforced jets has been debated all along.…”

Section: I3 Various Objectives Of Jet Controlmentioning

confidence: 99%

High Speed and High Reynolds Number Jet Control Using Arc Filament Plasma Actuators for Noise Mitigation and for Flow and Noise Diagnostics

Samimy

Kearney-Fisher

Sinha

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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We have developed a class of plasma actuators called localized arc filament plasma actuators (LAFPAs) for high-speed and high Reynolds number flow control. Over the past several years, we have successfully used these wide bandwidth (0 to 200 kHz) and individually-controlled actuators to excite the jet shear layer, jet column, and azimuthal instabilities in high subsonic and supersonic jets for either mixing enhancement or noise reduction purpose. In this paper, we provide a brief summary of our work and highlight the capabilities and potential of the actuators and the control technique for not only mixing enhancement and noise mitigation but also for flow and acoustic diagnostics. The jet 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 (0.2x10 6 to 1.65x10 6 ). Over this entire space of operating conditions, the jet is found to respond to control with a large range of forcing Strouhal numbers and azimuthal modes. The investigations reveal that the jet flow field and acoustic far-field can be dramatically altered, providing a powerful control tool in these practical high-speed and high Reynolds number jets. Sample flow and acoustic results are also presented to demonstrate the capabilities of these actuators and the control technique for flow and acoustic diagnostics.

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Seeding of helical modes in the initial region of an axisymmetric jet

Cited by 26 publications

References 11 publications

Resonance in Axisymmetric Jet Under Controlled Helical, Fundamental, and Axisymmetric Subharmonic Forcing

Resonance in Axisymmetric Jet Under Controlled Helical, Fundamental, and Axisymmetric Subharmonic Forcing

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

High Speed and High Reynolds Number Jet Control Using Arc Filament Plasma Actuators for Noise Mitigation and for Flow and Noise Diagnostics

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