Jet resonance in truncated ideally contoured nozzles

Bakulu, Florian; Lehnasch, Guillaume; Jaunet, Vincent; Silva, Eric Goncalvès da; Girard, Steve

doi:10.1017/jfm.2021.351

Cited by 4 publications

(2 citation statements)

References 39 publications

(100 reference statements)

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“…The drag coefficient C d and the shock stand-off distance ∆ s (normalized by D) are presented and compared in Table 6. A body-fitted simulation has also been carried out with a validated in-house code [53]. IBM and penalization results show a well agreement with the results of Takahashi et al [54], Kumar et al [55] and Riahi et al [40].…”

Section: Compressible Flows 321 Case 3: Supersonic Flow Past a Circul...supporting

confidence: 70%

Assessment of volume penalization and immersed boundary methods for compressible flows with various thermal boundary conditions

Ménez,

Parnaudeau,

Beringhier

et al. 2023

Journal of Computational Physics

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Section: Compressible Flows 321 Case 3: Supersonic Flow Past a Circul...supporting

confidence: 70%

Assessment of volume penalization and immersed boundary methods for compressible flows with various thermal boundary conditions

Ménez,

Parnaudeau,

Beringhier

et al. 2023

Journal of Computational Physics

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“…In the last decade, several studies have exploited high-fidelity simulation data sets to extract the relevant dynamical features of both compression ramps and oblique shock reflections (Pirozzoli et al 2010;Grilli et al 2012;Nichols et al 2017;Martelli et al 2020;Bakulu et al 2021). For example, Priebe et al (2016) applied dynamic mode decomposition (DMD) to the data obtained through direct numerical simulation (DNS) of a Mach 2.9 compression ramp STBLI, and found a strong similarity between DMD modes and linear stability modes reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Unsteadiness characterisation of shock wave/turbulent boundary-layer interaction at moderate Reynolds number

et al. 2023

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A direct numerical simulation of an oblique shock wave impinging on a turbulent boundary layer at Mach number 2.28 is carried out at moderate Reynolds number, simulating flow conditions similar to those of the experiment by Dupont et al. (J. Fluid Mech., vol. 559, 2006, pp. 255–277). The low-frequency shock unsteadiness, whose characteristics have been the focus of considerable research efforts, is here investigated via the Morlet wavelet transform. Owing to its compact support in both physical and Fourier spaces, the wavelet transformation makes it possible to track the time evolution of the various scales of the wall-pressure fluctuations. This property also makes it possible to define a local intermittency measure, representing a frequency-dependent flatness factor, to pinpoint the bursts of energy that characterise the shock intermittency scale by scale. As a major result, wavelet decomposition shows that the broadband shock movement is actually the result of a collection of sparse events in time, each characterised by its own temporal scale. This feature is hidden by the classical Fourier analysis, which can only show the time-averaged behaviour. Then, we propose a procedure to process any relevant time series, such as the time history of the wall pressure or that of the separation bubble extent, in which we use a condition based on the local intermittency measure to filter out the turbulent content in the proximity of the shock foot and to isolate only the intermittent component of the signal. In addition, wavelet analysis reveals the intermittent behaviour also of the breathing motion of the recirculation bubble behind the reflected shock, and allows us to detect a direct, partial correspondence between the most significant intermittent events of the separation region and those of the wall pressure at the foot of the shock.

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Impinging shear layer instability in over-expanded nozzle dynamics

Tarsia Morisco,

Robinet,

Herpe

et al. 2023

Physics of Fluids

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When rocket engine nozzles operate at a high degree of over-expansion, an internal flow separation occurs with a strong unsteady shock–wave boundary layer interaction. The global dynamics results in a low-frequency mode, which is associated with the shock displacement, and a high-frequency mode, which is correlated with the shear layer–boundary layer interaction. While the mechanism responsible for the low-frequency oscillation is known, the one in charge of the high-frequency unsteadiness is not yet clear. The scope of this paper is to provide a physical explanation for this mechanism. To do that, a delayed detached eddy simulation is used to numerically reproduce the flow in the case of a sub-scale cold-gas truncated ideal contour nozzle. The obtained results are successfully compared to the experiments and confirm the presence of two non-axisymmetric wall pressure signatures at Strouhal numbers St=fDj/Uj≃0.2 and 0.3 with different azimuthal selections. To reveal the origin of such modes, a power spectral density analysis is performed in the separated region. The analysis shows that both modes originate from the external shear layer and behave as “twins” in the separated region. The reason is that both modes are two sides of the same impinging shear layer instability: the acoustic mode propagates with the sound velocity, while the hydrodynamic one propagates with the supersonic shear layer velocity. In this context, the resulting self-sustained dynamics may be due to an acoustic–hydrodynamic feedback loop involving the impinging shear layer instability of the external supersonic shear layer and the separated region.

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Jet resonance in truncated ideally contoured nozzles

Abstract: Abstract

Cited by 4 publications

References 39 publications

Assessment of volume penalization and immersed boundary methods for compressible flows with various thermal boundary conditions

Assessment of volume penalization and immersed boundary methods for compressible flows with various thermal boundary conditions

Unsteadiness characterisation of shock wave/turbulent boundary-layer interaction at moderate Reynolds number

Impinging shear layer instability in over-expanded nozzle dynamics

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