Numerical Study of Laser-Spot Effects on Boundary-Layer Receptivity for Blunt Compression-Cones in Mach-6 Freestream

Huang, Yuet; Zhong, Xiaolin

doi:10.2514/6.2010-4447

Cited by 13 publications

(15 citation statements)

References 10 publications

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“…In the study of the smooth compression cone at the current freestream condition by Wheaton et al [22], no transition was observed, and the maximum N factor obtained from linear stability equation (LST) reached 14 at the end of the cone. In addition, Huang and Zhong [23,[25][26][27][28] have conducted extensive numerical and stability studies of boundary-layer receptivity to freestream hotspot perturbations with the same freestream conditions over a compression cone.…”

Section: A Test Model and Flow Conditionsmentioning

confidence: 99%

Second Mode Suppression in Hypersonic Boundary Layer by Roughness: Design and Experiments

Fong¹,

Wang²,

Huang³

et al. 2015

AIAA Journal

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Section: A Test Model and Flow Conditionsmentioning

confidence: 99%

Second Mode Suppression in Hypersonic Boundary Layer by Roughness: Design and Experiments

Fong¹,

Wang²,

Huang³

et al. 2015

AIAA Journal

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“…The entropy core has Gaussian temperature or density distribution [3,4]. As discussed in Huang & Zhong [13], if the hotspot is relatively large compare to the cone nose, the influence from the acoustic weak shock is very small and negligible. In this case, the hotspot is modeled as a pure entropy perturbation without the acoustic waves.…”

Section: Modeling Equations Of Freestream Hotspot Perturbationmentioning

confidence: 97%

“…The peak radius is controlled by the Gaussian factor, σ. The hotspot size is referred to the actual hotspot size in Purdue's experiments [3,4], which is case A in Huang & Zhong [13]. The initial location of the hotspot is chosen to be 2 cm upstream to the origin of the coordinates along the x-coordinate.…”

Section: Freestream Hotspot Parametersmentioning

confidence: 99%

Parametric Study of Boundary-Layer Receptivity to Freestream Hot-Spot Perturbation over a Blunt Compression Cone

Huang

Zhong

2014

52nd Aerospace Sciences Meeting

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This paper presents the numerical simulations of transient flow under the interaction between freestream hotspot perturbations and bow-shock on Purdue's blunt compression cone with the effects of different nosebluntness and various freestream Mach numbers. The basic flow conditions are referring to Boeing/AFOSR Mach-6 Quiet tunnel (BAM6QT) at Purdue University. The simulations in this paper consist of two cases of different nose-radii and two cases of different freestream Mach numbers. The detailed analysis of the receptivity mechanisms is carried out with linear stability theory (LST). The simulation results agree well with LST analyses. The parametric study is performed by the comparisons of the simulation results with the Mach-6 results that have been carried out previously. The study shows the sharper cone destabilizes the boundary layer, and the higher freestream Mach number stabilizes it. The receptivity mechanisms under both effects are shown to be the same: the second mode instability is induced by the fast acoustic waves behind the shock in the nose region.2 disturbances and nonlinear breakdown of them. Therefore, the study of second mode receptivity and instability is particularly important.Most of the hypersonic vehicles have blunt noses in order to reduce aerodynamic heating. The bow-shock in front of the blunt nose creates an entropy layer, which will be swallowed by the boundary layer in downstream [8]. There is strong vorticity created by the entropy layer, which may affect the receptivity process in the flow region near the shock. In addition, the swallowing process of entropy layer has a strong effect on the boundary layer stability [7].Kovasznay [11] showed that weak disturbances in compressible flow can be decomposed into acoustic, entropy and vorticity disturbance. It is well-known [10] that, regardless of the type of disturbances in the freestream hitting the shock, the interaction with the shock always generates all three kinds of disturbances, namely acoustic, entropy and vorticity disturbances. However, the mechanisms of the interaction of various types of disturbance with the shock are individually different, which would lead to difference in travelling angle and amplitude of the generated disturbances. In nature, the disturbances exist in freestream during flight in atmosphere consist of all three kinds. Thus, detailed boundary layer receptivity studies of all three types of freestream disturbance and shock interaction are necessary for completely understanding the mechanism of hypersonic boundary layer receptivity over blunt body. The receptivity to freestream acoustic disturbances has been studied extensively by many researchers [3,4]. There is experimental effort at Purdue University to use laser equipments to generate hotspots in a wind tunnel [3,4]. The goal is to study the generation of the second mode by using freestream entropy perturbations.The study in this paper is motivated by the experiments at Purdue University. The purpose of the current study is to conduct numerical inves...

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“…Past computational and theoretical receptivity studies have included investigations of acoustic waves, 5-7 of vorticity waves, 8 of discrete particles, 9 and of small entropic disturbances. [10][11][12][13][14] However, receptivity experiments are difficult to perform, making it challenging to validate the computational and theoretical studies. Experimental studies have largely been in the subsonic regime, and the few existing high-speed studies typically use disturbances that are not easily characterized.…”

Section: Introductionmentioning

confidence: 99%

Boundary Layer Instabilities Generated by Freestream Laser Perturbations

Chou

Schneider

2015

53rd AIAA Aerospace Sciences Meeting

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A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 −6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.

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Numerical Study of Laser-Spot Effects on Boundary-Layer Receptivity for Blunt Compression-Cones in Mach-6 Freestream

Cited by 13 publications

References 10 publications

Second Mode Suppression in Hypersonic Boundary Layer by Roughness: Design and Experiments

Second Mode Suppression in Hypersonic Boundary Layer by Roughness: Design and Experiments

Parametric Study of Boundary-Layer Receptivity to Freestream Hot-Spot Perturbation over a Blunt Compression Cone

Boundary Layer Instabilities Generated by Freestream Laser Perturbations

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