Hypersonic Boundary Layer Receptivity over a Blunt Cone to Freestream Pulse Disturbances

He, Simon; Zhong, Xiaolin

doi:10.2514/6.2020-2057

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…Hypersonic leading-edge acoustic receptivity studies by Cerminara and Sandham [16] on blunt wedges predicted that wall response for fast waves results in strong resonant amplification of mode F [17] and the corresponding response to slow waves exhibits an initial decay and an overall lower amplitude. He and Zhong [18] studied the receptivity effects of freestream slow, fast acoustic, and entropic perturbations on a blunt cone at Mach 9 and reported that axisymmetric fast acoustic disturbances generate the largest initial second-mode amplitudes, followed by the axisymmetric hotspot and then the axisymmetric slow acoustic pulse. Modal amplification of entropy-layer instabilities indicated that the growth-rate of these disturbances were too low to initiate transition [19,20].…”

Section: Introductionmentioning

confidence: 99%

Role of entropic-instabilities in laminar-turbulent transition on a blunted flat plate

Goparaju¹,

Gaitonde²

2021

Preprint

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The effects of entropic-instabilities on the laminar-turbulent transition dynamics of a blunted flat plate at Mach 4 are numerically investigated through linear and nonlinear approaches. Linear wavepacket analysis reveals amplifying oblique first-modes as well as planar and oblique entropylayer disturbances. The receptivity of entropic-instabilities is found to be largest for actuation seeded in the entropy-layer; the corresponding linear evolution is characterized by an intensification in the wall-normal plane, coupled with streamwise tilting. Disturbances in the entropy-layer interact non-linearly with each other through the oblique breakdown mechanism, inducing streamwise streaks in the boundary-layer. These undergo further destabilization downstream leading to turbulence onset. Different mechanisms of interest are extracted with modal decomposition techniques best suited for each. Dynamic mode decomposition (DMD) reveals sinuous subharmonic oscillations induced by the entropic-disturbances as the dominant streak instability mechanism. On the other hand, spectral proper orthogonal decomposition (SPOD) elicits the slanted hook -shaped structures in the temperature perturbations, which are attributable to the Orr like-mechanism in the entropy-layer. Furthermore, cross-bispectral mode decomposition (CBMD) shows that the temperature perturbations amplify on the crests of the low-speed streaks in the entropy-layer and generates disturbances through triadic interactions. These newer disturbances further interact, resulting in the transfer of perturbation energy into the boundary-layer. This eventually leads to spanwise homogenization and near-wall streak generation, reflecting late nonlinear stages of transition. Towards the end of breakdown region, spectral broadening accompanied by the appearance of an inertial sub-range in the boundary-layer indicates the approach of the flow towards turbulence.

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Section: Introductionmentioning

confidence: 99%

Role of entropic-instabilities in laminar-turbulent transition on a blunted flat plate

Goparaju¹,

Gaitonde²

2021

Preprint

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The effects of nose bluntness on broadband disturbance receptivity in hypersonic flow

Zhong

2022

Physics of Fluids

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While nose bluntness is known to have a large impact on the stability of hypersonic vehicles, its influence on the freestream receptivity process has not been fully characterized for a wide range of conditions. This paper investigates the effects of nose bluntness on the second mode receptivity coefficients and the development of boundary layer disturbances over two 7 degree half-angle circular blunt cones at mach 10 after perturbation with broadband freestream pulses of different types. The cones have nose radii of 9.525 mm (Case B) and 5.08 mm (Case I). Unsteady direct numerical simulation (DNS) and linear stability theory (LST) results compare well and predict stronger second mode growth for Case I in all pulse cases. Unsteady DNS also shows variations in extramodal excitation between the cones depending on freestream disturbance type. Spectral receptivity coefficients are generated by decomposing the unsteady DNS data into discrete frequency Fourier modes which are then corrected with LST N-factors. Fast acoustic disturbances demonstrate minimal variation in receptivity coefficients, while temperature and vorticity disturbances have much higher coefficients in Case I. Planar slow acoustic pulses induce stronger disturbances outside of the second mode in Case, resulting in higher peak receptivity coefficients. Results show significant variation in receptivity response based on nose bluntness, pulse geometry, and the type of the incident perturbation.

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Real-Gas Effects on Hypersonic Boundary-Layer Receptivity to Freestream Acoustic Disturbances

Varma

Zhong

2022

AIAA SCITECH 2022 Forum

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Hypersonic Boundary Layer Receptivity over a Blunt Cone to Freestream Pulse Disturbances

Cited by 3 publications

References 35 publications

Role of entropic-instabilities in laminar-turbulent transition on a blunted flat plate

Role of entropic-instabilities in laminar-turbulent transition on a blunted flat plate

The effects of nose bluntness on broadband disturbance receptivity in hypersonic flow

Real-Gas Effects on Hypersonic Boundary-Layer Receptivity to Freestream Acoustic Disturbances

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