Journal ArticleDOI
Aeroacoustic modal analysis of underexpanded pipe jets with and without an upstream cavity
Kabilan Baskaran,K.N. Srinivasan +1 more
TLDR
In this article, aero-acoustics of an underexpanded pipe-cavity jet are investigated experimentally using high-speed schlieren imaging techniques.Abstract:
The investigation of the aeroacoustics of an underexpanded pipe-cavity jet is carried out experimentally. Two different aspect ratios of the cavity are tested for a wide range of nozzle pressure ratios. Both internal and externally radiated pipe-cavity acoustics are studied. Linear and higher-order spectral analyses are implemented on the unsteady cavity pressure to comprehend the nature of the cavity acoustics and nonlinear interactions of different acoustic modes of the pipe–cavity system. Results show that an increase in depth leads to an enhancement in the nonlinear interactions. Furthermore, the power spectral and overall sound pressure level analyses of pipe and pipe-cavity jet noise radiation are carried out. High-speed schlieren imaging techniques are used to understand jet dynamics. Highly unsteady motion of the jet initial shear layer is observed due to an upstream disturbance of the cavity. In addition, proper orthogonal and dynamic mode decomposition methods are used to extract the spatial and dynamic modes of the jet structure. These methods are used to segregate the cavity associated jet dynamics and screech dynamics.read more
Citations
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Journal ArticleDOI
Shock and shear layer interaction in a confined supersonic cavity flow
TL;DR: In this paper, the impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached-eddy simulation, and the resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, spectral analysis, and modal decomposition.
Journal ArticleDOI
Shock and shear layer interactions in a confined supersonic cavity flow
TL;DR: In this article, the impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached eddy simulation, and the resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, x-t diagrams, spectral analysis, and modal decomposition.
Journal ArticleDOI
Modal analysis of mixing characteristics in scramjet combustor with passive struts
TL;DR: In this article , two passive struts are placed at a short distance downstream of the fuel injection strut to evaluate the effect of these struts in the mixing of air/fuel.
References
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Journal ArticleDOI
Role of initial conditions on noise from underexpanded pipe jets
T. J. S. Jothi,K.N. Srinivasan +1 more
TL;DR: In this paper, an experimental investigation of acoustic radiation from underexpanded air jets of different shear layer thicknesses has been performed, and the authors characterized the acoustic radiation in terms of overall sound pressure level, directivity, tonal, and broadband shock associated noise.
Journal ArticleDOI
Tone excited jets, part II: Flow visualization
Krishan K. Ahuja,M.C. Whiffen +1 more
TL;DR: In this paper, the second in a series of five papers that describe Lockheed's work on tone excited jest, the authors presented schlieren photographs of such jets obtained by an ensemble averaging method, which consisted of phase locking the large scale turbulence structures and multiple exposure of a given photographic film, and made it possible to photographically separate out the large-scale turbulence structures from the small scale random turbulence.
Journal ArticleDOI
Investigating mode competition and three-dimensional features from two-dimensional velocity fields in an open cavity flow by modal decompositions
TL;DR: In this paper, the authors apply both proper orthogonal decomposition and dynamic mode decomposition to experimental two-dimensional two-components time and spaced velocity fields of an incompressible open cavity flow, in a regime of mode competition.
Journal ArticleDOI
Oscillatory mode transition for supersonic open cavity flows
TL;DR: In this paper, the transition in the primary oscillatory mode in an open cavity has been experimentally investigated and the associated characteristics in a Mach 1.71 flow has been analyzed and the length-to-depth (L/D) ratios of the rectangular cavities are varied from 1.67 to 3.33.
Journal ArticleDOI
Flow dynamics in a variable-spacing, three bluff-body flowfield
TL;DR: In this article, the wake dynamics of systems with three bluff bodies with variable spacing are explored. But, the wake vortices have a regular and predictable periodicity, and the coherent dynamics of the wakes are highly intermittent.
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