Space-time correlation measurements in a hypersonic transitional boundary layer

Kimmel, Roger L.; Demetriades, Anthony; Donaldson, Joseph

doi:10.2514/6.1995-2292

Cited by 20 publications

(18 citation statements)

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“…10. Since Kimmel 6,15 defines transition onset over a straight cone as the streamwise location where the second mode amplitudes reach a maximum before decaying, transition onset does not occur in the present work. However, transition onset estimated from the surface temperatures occurs in the range R=1960-1990 as previously discussed.…”

Section: Boundary Layer Fluctuation Datamentioning

confidence: 84%

Hypersonic boundary layer stability over a flared cone in a quiet tunnel

Lachowicz

Chokani

Wilkinson

1996

34th Aerospace Sciences Meeting and Exhibit

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Hypersonic boundary layer measurements were conducted over a flared cone in a quiet wind tunnel. The flared cone was tested at a freestream unit Reynolds number of 2.82x10 6 /ft in a Mach 6 flow. This Reynolds number provided laminar-to-transitional flow over the model in a low-disturbance environment. Point measurements with a single hot wire using a novel constant voltage anemometry system were used to measure the boundary layer disturbances. Surface temperature and schlieren measurements were also conducted to characterize the laminar-to-transitional state of the boundary layer and to identify instability modes. Results suggest that the second mode disturbances were the most unstable and scaled with the boundary layer thickness. The integrated growth rates of the second mode compared well with linear stability theory in the linear stability regime. The second mode is responsible for transition onset despite the existence of a second mode sub-harmonic. The sub-harmonic wavelength also scales with the boundary layer thickness. Furthermore, the existence of higher harmonics of the fundamental suggests that non-linear disturbances are not associated with "high" free stream disturbance levels. Nomenclature

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Section: Boundary Layer Fluctuation Datamentioning

confidence: 84%

Hypersonic boundary layer stability over a flared cone in a quiet tunnel

Lachowicz

Chokani

Wilkinson

1996

34th Aerospace Sciences Meeting and Exhibit

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“…For the wind tunnel tests, the boundary-layer thickness on a 70 half-angle cone is approximately 1 mm (see §4.1 and figure 8). According to the experimental observations of Kendall (1975), Demetriades (1974), Stetson et al (1983), Stetson & Kimmell (1992a, b) and Kimmel et al (1995), the second-mode wavelength is approximately twice the boundary-layer thickness, i.e. it is --2 mm in the case considered.…”

Section: Uac Parametersmentioning

confidence: 82%

“…This instability belongs to the family of trapped acoustic modes propagating in a waveguide between the wall and the sonic line Guschin & Fedorov 1989). The existence of the second mode was established by the experiments of Kendall (1975), Demetriades (1974), Stetson et al (1983) Stetson & Kimmel (1992a,b) and Kimmel, Demetriades & Donaldson (1995). Once the second mode sets in, it becomes the dominant instability since its growth rate tends to exceed that of the first mode.…”

Section: Introductionmentioning

confidence: 98%

Mathematical Fluid Dynamics of Store and Stage Separation

Malmuth¹,

Шалаев²,

Федоров³

2005

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“…Besides the first vortex instability for the Mach mode, there arises a new, acoustic type of instability (the so-called second mode instability) [4]. Demetriades [5], Kendall [6], Stetson et al [7] were among the first to find the Mach mode in experiments, while Kimmel et al [8], Lachowicz et al [9], and Doggett et al [10] also observed the second mode later in their experiments separately. According to theoretical and numerical studies, the second mode in hypersonic flows is the dominant instability and is expected to govern the occurrence and development of laminar-turbulent transition [11].…”

Section: Introductionmentioning

confidence: 99%

Second mode unstable disturbance measurement of hypersonic boundary layer on cone by wavelet transform

2011

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Experimental investigation of hypersonic boundary layer instability on a cone is performed at Mach number 6 in a hypersonic wind tunnel. Time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface in the streamwise direction to investigate the development of the unstable disturbance. Wavelet transform is employed as a mathematical tool to obtain the multi-scale characteristics of fluctuating surfacethermal-flux both in the temporal and spectrum space. The conditional sampling algorithm using wavelet coefficient as an index is put forward to extract the unstable disturbance waveform from the fluctuating surface-thermal-flux signals. The generic waveform for the second mode unstable disturbance is obtained by a phase-averaging technique. The development of the unstable disturbance in the streamwise direction is assessed both in the temporal and spectrum space. Our study shows that the local unstable disturbance detection method based on wavelet transformation offers an alternative powerful tool in studying the hypersonic unstable mode of laminar-turbulent transition. It is demonstrated that, at hypersonic speeds, the dominant flow instability is the second mode, which governs the course of laminar-turbulent transition of sharp cone boundary layer.

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Space-time correlation measurements in a hypersonic transitional boundary layer

Cited by 20 publications

References 0 publications

Hypersonic boundary layer stability over a flared cone in a quiet tunnel

Hypersonic boundary layer stability over a flared cone in a quiet tunnel

Mathematical Fluid Dynamics of Store and Stage Separation

Second mode unstable disturbance measurement of hypersonic boundary layer on cone by wavelet transform

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