Theoretical model for coupled dual impinging jet aeroacoustic resonance

Stahl, Spencer L.; Gaitonde, Datta V.; Bhargav, Vikas N.; Alvi, Farrukh S.

doi:10.1103/physrevfluids.7.104606

Cited by 2 publications

(1 citation statement)

References 31 publications

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“…Recent work by Stahl et al. (2022) and Webb et al. (2023) have shown that modelling each jet and their coupling can describe the flow resonance of twin-jet systems.…”

Section: Twin-jet Screech Feedback Scenariosmentioning

confidence: 99%

A closure mechanism for screech coupling in rectangular twin jets

Jeun,

Wu,

Lele

2024

J. Fluid Mech.

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The twin-jet configuration allows two different scenarios to close the screech feedback. For each jet, there is one loop involving disturbances which originate in that jet and arrive at its own receptivity point in phase (self-excitation). The other loop is associated with free-stream acoustic waves that radiate from the other jet, reinforcing the self-excited screech (cross-excitation). In this work, the role of the free-stream acoustic mode and the guided-jet mode as a closure mechanism for twin rectangular jet screech is explored by identifying eligible points of return for each path, where upstream waves propagating from such a point arrive at the receptivity location with an appropriate phase relation. Screech tones generated by these jets are found to be intermittent with an out-of-phase coupling as a dominant coupling mode. The instantaneous phase difference between the twin jets computed by the Hilbert transform suggests that a competition between out-of-phase and in-phase coupling is responsible for the intermittency. To model wave components of the screech feedback while ensuring perfect phase locking, an ensemble average of leading spectral proper orthogonal decomposition modes is obtained from several segments of large-eddy simulation data that correspond to periods of invariant phase difference between the two jets. Each mode is then extracted by retaining relevant wavenumber components produced via a streamwise Fourier transform. Spatial cross-correlation analysis of the resulting modes shows that most of the identified points of return for the cross-excitation are synchronised with the guided jet mode self-excitation, supporting that it is preferred in closing rectangular twin-jet screech coupling.

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“…Recent work by Stahl et al. (2022) and Webb et al. (2023) have shown that modelling each jet and their coupling can describe the flow resonance of twin-jet systems.…”

Section: Twin-jet Screech Feedback Scenariosmentioning

confidence: 99%

A closure mechanism for screech coupling in rectangular twin jets

Jeun,

Wu,

Lele

2024

J. Fluid Mech.

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Effect of Relative Jet Temperature in Supersonic Dual-Impinging Jets

2023

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Short takeoff and vertical landing aircraft configurations involve multiple jets that impinge onto the deck surface in tandem and lead to several adverse effects. This study reports on the experimental characterization of supersonic dual-impinging jets by systematically varying their relative jet temperature. A sonic converging and Mach 1.5 converging–diverging (CD) nozzles are employed. The expansion ratio of the converging nozzle is maintained at 0.96, 1.19, and 1.59, and the CD nozzle is operated at a fixed nozzle pressure ratio of 3. The temperature ratio of the jet from the CD nozzle is varied from 1.0, 1.3, and 1.7. For a fixed momentum of the jet pair, an increase in jet temperature intensified the nearfield noise and unsteadiness on the impingement surface. At short impingement heights, resonance in the heated jet was the primary source of unsteadiness. At a fixed impingement height, an increase in jet temperature led to a systematic increase in tonal frequency, while jet instability mode shapes were retained. Furthermore, the mean flowfield of sonic jet and fountain regions remain unaffected, and an increase in supersonic jet velocity is observed. This is also accompanied by an increase in unsteadiness in the fountain upwash.

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Theoretical model for coupled dual impinging jet aeroacoustic resonance

Cited by 2 publications

References 31 publications

A closure mechanism for screech coupling in rectangular twin jets

A closure mechanism for screech coupling in rectangular twin jets

Effect of Relative Jet Temperature in Supersonic Dual-Impinging Jets

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