Effects of freestream turbulence on boundary- layer transition.

Wells, C. S.

doi:10.2514/3.3931

Cited by 61 publications

(13 citation statements)

References 7 publications

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“…Although freestream disturbances may have a strong influence on boundary layer transition, and it is a general trend that transition Reynolds number decreases with increasing freestream disturbance level* 18 ), large freestream parameter fluctuation intensities do not always mean strong disturbances to the boundary layer instability and transition. The support of this conclusion came from Wells's* 19 ) experimental investigation of the effect of freestream turbulence on boundary layer transition for zero pressure gradient at low speed. He compared his measurements with those of Schubauer and Skramstad( 2°) and Boltz et aV-2v > and it was found that at the same freestream velocity fluctuation intensity, the transition Reynolds number could be expected to have different values.…”

Section: ^1= 4 C 7^ Re Idrelmentioning

confidence: 92%

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Transition of compressible high enthalpy boundary layer flow over a flat plate

Morgan

1994

Aeronaut. j.

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This paper presents the results of an experimental investigation into the characteristics of boundary layer transition to turbulence in hypervelocity air flows. A series of experiments was conducted using a flat plate model, equipped with static pressure and thin film heat transfer transducers, in a free piston shock tunnel. Transition was observed in the stagnation enthalpy range of 2·35 to 19·2 MJ/kg. The transition Reynolds number correlates well with the unit Reynolds number through a simple empirical relation. The influences of Mach number, pressure and wall cooling are examined. The measured heat transfer rates in laminar and turbulent regions are compared with empirical predictions. Freestream disturbances of the test flow were also measured and analysed.

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Section: ^1= 4 C 7^ Re Idrelmentioning

confidence: 92%

“…The Re,-Re" relationship was compared with experimental and theoretical results of other investigators in where c = 13-8, and was also determined through the experiment. Equations (21) and (22) are substituted into Equation (19) to calculate the intermittency factor.…”

Section: >)mentioning

confidence: 99%

Transition of compressible high enthalpy boundary layer flow over a flat plate

Morgan

1994

Aeronaut. j.

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“…See Wells. 21 Sensitivity of the results to grid size are shown in Fig. 9, for the case with T u = 0.2%.…”

Section: Resultsmentioning

confidence: 99%

Analysis of Transition-Sensitized Turbulent Transport Equations

Rumsey

Thacker

Gatski

et al. 2005

43rd AIAA Aerospace Sciences Meeting and Exhibit

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The dynamics of an ensemble of linear disturbances in boundary-layer flows at various Reynolds numbers is studied through an analysis of the transport equations for the mean disturbance kinetic energy and energy dissipation rate. Effects of adverse and favorable pressure-gradients on the disturbance dynamics are also included in the analysis. Unlike the fully turbulent regime where nonlinear phase scrambling of the fluctuations affects the flow field even in proximity to the wall, the early stage transition regime fluctuations studied here are influenced across the boundary layer by the solid boundary. The dominating dynamics in the disturbance kinetic energy and dissipation rate equations are described. These results are then used to formulate transitionsensitized turbulent transport equations, which are solved in a two-step process and applied to zero-pressuregradient flow over a flat plate. Computed results are in good agreement with experimental data.

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“…Actually, this discrepancy is somewhat expected given the model initial conditions. Experiments of natural transition show a wide range of transition locations from a high value of Re x = 5.0 × 10 6 measured by [18] to classical predictive theories, such as the e 9 rule, which predict a value of 2.0 × 10 6 [17]. This range of results is commonly attributed to different noise levels in the various experiments.…”

Section: Flat Plate Boundary Layer In Zero Pressure Gradientmentioning

confidence: 99%

“…It was mentioned previously that acoustic effects (wind tunnel noise) can have a fairly strong influence on natural transition. The experiment of [18] is commonly assumed to be largely free of acoustic noise, and therefore gives a high 'quiet' transition location of Re x,tr = 5.0 × 10 6 . Our…”

Section: Acoustic Effects On Natural Transitionmentioning

confidence: 99%

Prediction of turbulent transition in boundary layers using the turbulent potential model

Wang¹,

Perot²

2002

Journal of Turbulence

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A turbulent potential model is applied to predict the transition in boundary flows. Without assuming any constitutive relation between the turbulence and mean flow variables, this model has the ability to accurately predict strong non-equilibrium flows, but the computation cost for this is only comparable to two equation models and so is the model complexity. Model predictions for a number of transitional flows are presented, which include: bypass transition and natural transition flat plate occurring in Blasius boundary flows with a series of free-stream turbulence intensities, effects of pressure gradients, relaminarization in channel flow and the sensitivity of natural transition to acoustic level. The results are compared to experimental data and other model predictions whenever possible.

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Effects of freestream turbulence on boundary- layer transition.

Cited by 61 publications

References 7 publications

Transition of compressible high enthalpy boundary layer flow over a flat plate

Transition of compressible high enthalpy boundary layer flow over a flat plate

Analysis of Transition-Sensitized Turbulent Transport Equations

Prediction of turbulent transition in boundary layers using the turbulent potential model

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