Simulations of Initially Highly Disturbed Jets with Experiment-Like Exit Boundary Layers

Bogey, Christophe; Marsden, Olivier

doi:10.2514/1.j054426

Cited by 35 publications

(35 citation statements)

References 81 publications

(146 reference statements)

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“…The numerical framework is identical to that used in recent simulations of spatially developing [49][50][51] and temporally developing [25,42] round jets. The simulations are carried out using an in-house solver of the three-dimensional filtered compressible Navier-Stokes equations in cylindrical coordinates (r, θ, z) based on low-dissipation and low-dispersion, high-order explicit schemes.…”

Section: B Numerical Methodsmentioning

confidence: 99%

Potential-core closing of temporally developing jets at Mach numbers between 0.3 and 2: Scaling and conditional averaging of flow and sound fields

Bogey

Pineau

2019

Phys. Rev. Fluids

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In a previous work [Bogey, J. Fluid Mech. 859, 1022 (2019)], the potential-core closing of temporally developing isothermal round jets at a Mach number M = 0.9 was shown to generate a strong axisymmetric noise component in the downstream direction. The persistence of this component is investigated in the present work for jets at M = 0.3, 0.6, 1.3, and 2 computed by direct numerical simulation, from a low subsonic to a high supersonic Mach number. The flow and sound fields are presented, and the Mach number scaling of their magnitudes and spectral content is examined. The centerline velocity and hydrodynamic pressure spectra are close to each other using k z r 0 in abscissa, where k z and r 0 are the axial wave number and the initial jet radius, respectively. The sound spectra for M 1.3 collapse well when they are plotted as a function of k z r 0 M −1 and adjusted in amplitude using a M 7.5 power law, whereas a k z r 0 scaling and a lower power-law exponent seem to apply to the spectra for M 1.3. The flow and sound fields are then correlated with each other, and conditionally averaged based on a synchronization of the fields with the minimum values of centerline velocity at potential-core closing. The noise component radiated in the downstream direction for M = 0.9 is clearly identified for M = 0.6, 1.3, 2, and is also detected, albeit with more difficulty, for M = 0.3, indicating the presence of the associated sound source over a wide range of Mach numbers. In all cases, its generation process extracted by the conditional averaging consists in the growth of a spot of low velocity and a high vorticity level in the inner side of the mixing layer, reaching a peak intensity at its arrival on the axis and weakening subsequently. The use of different trigger conditions for the averaging suggests that, for a given Mach number, the amplitude of the acoustic waves radiated during that stage depends linearly on the velocity deficit and the strength of the vortical structures on the jet centerline at the time of potential-core closing.

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Section: B Numerical Methodsmentioning

confidence: 99%

Potential-core closing of temporally developing jets at Mach numbers between 0.3 and 2: Scaling and conditional averaging of flow and sound fields

Bogey

Pineau

2019

Phys. Rev. Fluids

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“…The numerical framework is identical to that used in recent simulations of round jets (Bogey & Bailly 2010;Bogey, Marsden & Bailly 2012, 2011bBogey & Marsden 2016). The simulations have been carried out using an in-house solver of the three-dimensional filtered compressible Navier-Stokes equations in cylindrical coordinates (r, θ, z) based on low-dissipation and low-dispersion, high-order explicit schemes.…”

Section: Methodsmentioning

confidence: 99%

On noise generation in low Reynolds number temporal round jets at a Mach number of 0.9

Bogey

2018

J. Fluid Mech.

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Two temporally developing isothermal round jets at a Mach number of 0.9 and Reynolds numbers of 3125 and 12 500 are simulated in order to investigate noise generation in high-subsonic jet flows. Snapshots and statistical properties of the flow and sound fields, including mean, root-mean-square and skewness values, spectra and auto- and cross-correlations of velocity and pressure, are presented. The jet at a Reynolds number of 12 500 develops more rapidly, exhibits more fine turbulent scales and generates more high-frequency acoustic waves than the other. In both cases, however, when the jet potential core closes, mixing-layer turbulent structures intermittently intrude on the jet axis and strong low-frequency acoustic waves are emitted in the downstream direction. These waves are dominated by the axisymmetric mode and are significantly correlated with centreline flow fluctuations. These results are similar to those obtained at the end of the potential core of spatially developing jets. They suggest that the mechanism responsible for the downstream noise component of these jets also occurs in temporal jets, regardless of the Reynolds number. This mechanism is revealed by averaging the flow and pressure fields of the present jets using a sample synchronization with the minimum values of centreline velocity at potential-core closing. A spot characterized by a lower velocity and a higher level of vorticity relative to the background flow field is found to develop in the interfacial region between the mixing layer and the potential core, to strengthen rapidly and reach a peak intensity when arriving on the jet axis, and then to break down. This is accompanied by the growth and decay of a hydrodynamic pressure wave, propagating at a velocity which, initially, is close to 65 per cent of the jet velocity and slightly increases, but quickly decreases after the collapse of the high-vorticity spot in the flow. During that process, sound waves are radiated in the downstream direction.

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“…These values do not permit in theory to simulate with accuracy the turbulent boundary layer of the wall jet. However, using a similar solver, Bogey and Marsden [31] showed for the turbulent boundary layer developing in the nozzle of a turbulent subsonic jet that the LES results do not depend significantly on the mesh spacing in the direction normal to the wall for values Δ 3.7 and below.…”

Section: B Numerical Parametersmentioning

confidence: 99%

Flow Features near Plate Impinged by Ideally Expanded and Underexpanded Round Jets

Gojon

Bogey

2018

AIAA Journal

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Simulations of Initially Highly Disturbed Jets with Experiment-Like Exit Boundary Layers

Cited by 35 publications

References 81 publications

Potential-core closing of temporally developing jets at Mach numbers between 0.3 and 2: Scaling and conditional averaging of flow and sound fields

Potential-core closing of temporally developing jets at Mach numbers between 0.3 and 2: Scaling and conditional averaging of flow and sound fields

On noise generation in low Reynolds number temporal round jets at a Mach number of 0.9

Flow Features near Plate Impinged by Ideally Expanded and Underexpanded Round Jets

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