The Influence of Wind Tunnel Turbulence on the Boundary Layer Transition

Meier, H. U.; Michel, U.; Kreplin, H.-P.

doi:10.1007/978-3-642-82994-9_2

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…A linear dependence between H 12 and the transition Reynolds number was found for each combination of Mach and unit Reynolds number, which was approximated by linear functions with the intercepts, h II,0 , and slopes, h II,1 . It was, therefore, possible to show in this study that not the RMS turbulence level alone is meaningful for T-S induced transition, but instead the spectral level in the relevant frequency range has to be considered, as conjectured by Meier et al (1987). The relation between the spectral level and the frequency range relevant for T-S induced transition was used to explain and quantify the observed unit Reynolds number effect on the transition Reynolds number.…”

Section: Resultsmentioning

confidence: 89%

“…However, many conventional wind tunnels have disturbance levels higher than in flight, which can cause the mechanism of 'natural transition to be changed or bypassed and can lead to discrepancies between transition locations measured in wind tunnels and in flight (Fisher and Dougherty 1982;Michel and Froebel 1988) Results from Meier et al (1987) indicate that the movement of transition location is not determined by the root mean square (RMS) turbulence level, but instead by the spectral level in the frequency range, in which the T-S waves are most unstable. Therefore, they concluded from their experiments that "the Reynolds number at which the transition onset was detected can be correlated perfectly with the spectral level in the frequency range representative for the Tollmien-Schlichting waves" (Meier et al 1987).…”

Section: Introductionmentioning

confidence: 99%

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Unit Reynolds number, Mach number and pressure gradient effects on laminar–turbulent transition in two-dimensional boundary layers

et al. 2018

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The influence of unit Reynolds number (Re 1 = 17.5 × 10 6-80 × 10 6 m −1), Mach number (M = 0.35-0.77) and incompressible shape factor (H 12 = 2.50-2.66) on laminar-turbulent boundary layer transition was systematically investigated in the Cryogenic Ludwieg-Tube Göttingen (DNW-KRG). For this investigation the existing two-dimensional wind tunnel model, PaLASTra, which offers a quasi-uniform streamwise pressure gradient, was modified to reduce the size of the flow separation region at its trailing edge. The streamwise temperature distribution and the location of laminar-turbulent transition were measured by means of temperature-sensitive paint (TSP) with a higher accuracy than attained in earlier measurements. It was found that for the modified PaLASTra model the transition Reynolds number (Re tr) exhibits a linear dependence on the pressure gradient, characterized by H 12. Due to this linear relation it was possible to quantify the so-called 'unit Reynolds number effect', which is an increase of Re tr with Re 1. By a systematic variation of M, Re 1 and H 12 in combination with a spectral analysis of freestream disturbances, a stabilizing effect of compressibility on boundary layer transition, as predicted by linear stability theory, was detected ('Mach number effect'). Furthermore, two expressions were derived which can be used to calculate the transition Reynolds number as a function of the amplitude of total pressure fluctuations, Re 1 and H 12. To determine critical N-factors, the measured transition locations were correlated with amplification rates, calculated by incompressible and compressible linear stability theory. By taking into account the spectral level of total pressure fluctuations at the frequency of the most amplified Tollmien-Schlichting wave at transition location, the scatter in the determined critical N-factors was reduced. Furthermore, the receptivity coefficients dependence on incidence angle of acoustic waves was used to correct the determined critical N-factors. Thereby, a found dependency of the determined critical N-factors on H 12 decreased, leading to an average critical N-factor of about 9.5 with a standard deviation of ≈ 0.8.

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Section: Resultsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Unit Reynolds number, Mach number and pressure gradient effects on laminar–turbulent transition in two-dimensional boundary layers

et al. 2018

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“…Their linear stability analysis of local (parallel) jet profiles has revealed a change from convective to absolute instability (see Refs. Meier et al (1987)) and flow separation (e.g. Meier et al (1987)) and flow separation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Advances in Turbulence 2

Fernholz¹,

Fiedler²

1989

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“…Results from Meier et al (1987) indicate that the movement of transition location is not determined by the RMS (root mean square) turbulence level, but instead by the spectral level in the frequency range, in which the T-S waves are most unstable. Therefore they concluded from their experiments that "the Reynolds number at which the transition onset was detected can be correlated perfectly with the spectral level in the frequency range representative for the Tollmien-Schlichting waves" (Meier et al, 1987).…”

Section: Introductionmentioning

confidence: 92%

“…However, many conventional wind tunnels have disturbance levels higher than in flight, which can cause the mechanism of 'natural' transition to be changed or bypassed and can lead to discrepancies between transition locations measured in wind tunnels and in flight (Fisher and Dougherty, 1982;Michel and Froebel, 1988). Results from Meier et al (1987) indicate that the movement of transition location is not determined by the RMS (root mean square) turbulence level, but instead by the spectral level in the frequency range, in which the T-S waves are most unstable. Therefore they concluded from their experiments that "the Reynolds number at which the transition onset was detected can be correlated perfectly with the spectral level in the frequency range representative for the Tollmien-Schlichting waves" (Meier et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Development of a time-resolved quantitative surface-temperature measurement technique and its application in short-duration wind tunnel testing

Risius¹

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Weiss and Dr. D. Yorita. I am very glad and thankful to be part of this group of wonderful people, who have become far more than colleagues to me.The wind tunnel measurement campaigns would not have been possible without the help of the colleagues M. Aschoff, Dr. M. Bruse, A. Grimme, S. Hucke, R. Kahle, M. Löhr and K. Plettenberg from the German-Dutch Wind Tunnels (DNW). I am also grateful to the Head of the Experimental Methods department, Dr. L. Koop, and many other colleagues from DLR Göttingen who supported me throughout the years, in particular J. Agocs, Dr.

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The Influence of Wind Tunnel Turbulence on the Boundary Layer Transition

Cited by 11 publications

References 7 publications

Unit Reynolds number, Mach number and pressure gradient effects on laminar–turbulent transition in two-dimensional boundary layers

Unit Reynolds number, Mach number and pressure gradient effects on laminar–turbulent transition in two-dimensional boundary layers

Advances in Turbulence 2

Development of a time-resolved quantitative surface-temperature measurement technique and its application in short-duration wind tunnel testing

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