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

Fong, Kahei Danny; Wang, Xiaowen; Huang, Yuet; Zhong, Xiaolin; McKiernan, Gregory; Fisher, Roy; Schneider, Steven P.

doi:10.2514/1.j054100

Cited by 72 publications

(47 citation statements)

References 27 publications

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“…The way the latter impacts the transition in high-speed boundary layers is still unclear. Most of the studies involving surface imperfections looked at isolated roughness elements of different shapes (Fong et al [15,16,17,18], Duan et al [19], Park and Park [20], Mortensen and Zhong [36], Bountin et al [21]). A comprehensive review about the effect of different roughness elements on hypersonic boundary layers can be found in Schneider [22].…”

Section: Introductionmentioning

confidence: 99%

“…It was found that a wavy surface with the wavelength equal to twice the boundary layer thickness delayed the transition onset. Duan et al [19] and Fong et al [15,16,17,18] in a series of studies investigated the effect of two-dimensional roughness on the instability of the second mode (or mode S) by direct numerical simulations (DNS). Their numerical results proved that the roughness located at the downstream of the synchronization point is able to stabilize this mode.…”

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confidence: 99%

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Assessment of the Impact of Two-Dimensional Wall Deformation Shape on High-Speed Boundary-Layer Disturbances

et al. 2018

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Previous experimental and numerical studies showed that two-dimensional roughness elements can stabilize disturbances inside a hypersonic boundary layer, and eventually delay the transition onset. The objective of this paper is to evaluate the response of disturbances propagating inside a high-speed boundary layer to various two-dimensional surface deformations of different shapes. We perform an assessment of the impact of various 2D surface non-uniformities, such as backward or forward steps, combinations of backward and forward steps, wavy surfaces, surface dips, and surface humps. Disturbances inside a Mach 5.92 flat-plate boundary layer are excited using periodic wall blowing and suction at an upstream location. The numerical tools consist of a high-accurate numerical algorithm solving for the unsteady, compressible form of the Navier-Stokes equations in curvilinear coordinates. Results show that all types of surface non-uniformities are able to reduce the amplitude of boundary layer disturbances to a certain degree. The amount of disturbance energy reduction is related to the type of pressure gradients that are posed by the deformation (adverse or favorable). A possible cause (among others) of the disturbance energy reduction inside the boundary layer is presumed to be the result of a partial deviation of the kinetic energy to the external flow, along the discontinuity that is generated by the wall deformation. arXiv:1807.02197v1 [physics.flu-dyn] 5 Jul 2018 Khokhlov [26,27], Sakaue et al. [29], Fedorov [30]). In some of these studies, it was found that acoustic waves are very effective in exciting disturbances inside the boundary layer with amplitudes that become much larger than those in the free-stream, but this happens only above some critical Reynolds number as in the incompressible regime. Other studies (Fedorov and Khokhlov [26,27], Sakaue et al. [29], Fedorov [30]) were concerned about the generation of the first and second modes in the vicinity of the leading edge. The effect of all types of waves, i.e. slow and fast acoustic waves, vorticity waves and entropy waves, on supersonic boundary layers was studied and reported in a suite of papers by Balakumar [31,32,33]. The generation and the evolution of three-dimensional disturbances induced by slow and fast acoustic disturbances and isolated roughness elements in a supersonic boundary layer over flat plates and wedges were numerically investigated by solving the full three-dimensional Navier-Stokes equations. It was found that instability waves are generated within one wavelength of the acoustic wave from the leading edge.Previous experimental and numerical studies (Holloway and Sterrett [34], Fujii [35], Fong et al. [15, 16, 17, 18], Duan et al. [19], Park and Park [20], Mortensen and Zhong [36]) showed evidence that twodimensional roughness elements can reduce the amplitude of disturbances inside high-speed boundary layers. Holloway and Sterrett [34], for example, carried out early experiments on flat plate boundary layer disturbed by roughness ele...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Assessment of the Impact of Two-Dimensional Wall Deformation Shape on High-Speed Boundary-Layer Disturbances

et al. 2018

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“…This study found that a series of panels, deformed into the flow, significantly disrupted the unstable growth of disturbances excited in the absence of the deformations. The potential for 2-D wavy walls to stabilize hypersonic boundary layers has also been observed for roughness scale deformations [23][24][25][26][27][28], in which the protuberances alter the local flowfield as opposed to introducing global pressure gradients.…”

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confidence: 89%

“…Boundary-layer stability is highly dependent on wall temperature [17,18] and surface geometry [18][19][20][21][22][23][24][25][26][27][28], both of which vary during flight for hot structure hypersonic vehicles. Previous studies have examined how aerothermoelastic effects, such as thermally induced deformations, can augment aerothermal loads [29,30] and impact boundary-layer transition [31,32].…”

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confidence: 99%

Characterization of Structural Response to Hypersonic Boundary-Layer Transition

et al. 2016

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The inherent relationship between boundary-layer stability, aerodynamic heating, and surface conditions makes the potential for interaction between the structural response and boundary-layer transition an important and challenging area of study in high-speed flows. This paper phenomenologically explores this interaction using a fundamental two-dimensional aerothermoelastic model under the assumption of an aluminum panel with simple supports. Specifically, an existing model is extended to examine the impact of transition onset location, transition length, and transitional overshoot in heat flux and fluctuating pressure on the structural response of surface panels. Transitional flow conditions are found to yield significantly increased thermal gradients, and they can result in higher maximum panel temperatures compared to turbulent flow. Results indicate that overshoot in heat flux and fluctuating pressure reduces the flutter onset time and increases the strain energy accumulated in the panel. Furthermore, overshoot occurring near the midchord can yield average temperatures and peak displacements exceeding those experienced by the panel subject to turbulent flow. These results suggest that fully turbulent flow does not always conservatively predict the thermo-structural response of surface panels. Nomenclature b = compressibility exponent c = specific heat capacity c f = skin-friction coefficient E = modulus of elasticity F c = compressible flow transformation function h = panel thickness k = thermal conductivity L = panel length p = unsteady aerodynamic pressurẽ p = root-mean-square fluctuating pressure Q = aerodynamic heat flux q = dynamic pressure Re θ = momentum thickness Reynolds number T = temperature t = time t F = panel flutter onset time u = fluid velocity w = transverse panel displacement x = chordwise spatial coordinate x t = transition onset location x te = end of transition region x = spatial location nondimensionalized by panel length z = through-thickness spatial coordinate α = thermal expansion coefficient β = standard deviation γ = intermittency Δx t = transition length (x te − x t ) δ 1 = boundary-layer displacement thickness Θ = overall phase angle λ = viscosity/velocity power law exponent ν = Poisson's ratio ρ = panel density σ = spot propagation parameter τ = temporal phase angle ϕ = power spectral density ψ = spatial phase angle ω = angular frequency Subscripts avg = average e = boundary-layer edge lam = laminar max = maximum tran = transitional turb = turbulent VO = virtual origin

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“…Kegerise, M. A measured the instability of the medium heat flux in the 6 Mach plate boundary layer. 8 The medium-pressure instability of the 6-Mach model boundary layer is measured by Fong, K. D., et al 9 Owen, F. K., et al measured the temperature instability in the Mach 7 free flow. 10 Unfortunately, as so far, there is no direct way to diagnose the time-varying electron density of the plasma sheath, which is most concerned in EM propagation.…”

Section: Introductionmentioning

confidence: 99%

An integrative time-varying frequency detection and channel sounding method for dynamic plasma sheath

et al. 2018

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The plasma sheath-surrounded hypersonic vehicle is a dynamic and time-varying medium and it is almost impossible to calculate time-varying physical parameters directly. The in-fight detection of the time-varying degree is important to understand the dynamic nature of the physical parameters and their effect on re-entry communication. In this paper, a constant envelope zero autocorrelation (CAZAC) sequence based on time-varying frequency detection and channel sounding method is proposed to detect the plasma sheath electronic density time-varying property and wireless channel characteristic. The proposed method utilizes the CAZAC sequence, which has excellent autocorrelation and spread gain characteristics, to realize dynamic time-varying detection/channel sounding under low signal-to-noise ratio in the plasma sheath environment. Theoretical simulation under a typical time-varying radio channel shows that the proposed method is capable of detecting time-variation frequency up to 200 kHz and can trace the channel amplitude and phase in the time domain well under –10 dB. Experimental results conducted in the RF modulation discharge plasma device verified the time variation detection ability in practical dynamic plasma sheath. Meanwhile, nonlinear phenomenon of dynamic plasma sheath on communication signal is observed thorough channel sounding result.

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

Cited by 72 publications

References 27 publications

Assessment of the Impact of Two-Dimensional Wall Deformation Shape on High-Speed Boundary-Layer Disturbances

Assessment of the Impact of Two-Dimensional Wall Deformation Shape on High-Speed Boundary-Layer Disturbances

Characterization of Structural Response to Hypersonic Boundary-Layer Transition

An integrative time-varying frequency detection and channel sounding method for dynamic plasma sheath

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