High Reynolds Number Transition Detection by Means of Temperature Sensitive Paint

Fey, Uwe; Egami, Yasuhiro; Engler, Rolf

doi:10.2514/6.2006-514

Cited by 37 publications

(38 citation statements)

References 2 publications

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“…For attached two-dimensional flows, T w /T aw > 1 enhances boundary layer instability and can cause transition to occur earlier than in the adiabatic case 20 -23 . On the other hand, the temperature difference between flow and model surface enables very accurate transition detection using the Temperature-Sensitive Paint (TSP) measurement technique 24 , 25 at DNW-KRG 20 , 23 , 25 , 26 . The custom-built design of the DNW-KRG facility and a special method for model handling and cleaning guarantee operation with clean flow conditions, which is crucial for NLF testing at high Reynolds numbers.…”

Section: Experimental Setup and Definition Of Parametersmentioning

confidence: 99%

Experimental Investigation of the Effect of Forward-facing Steps on Boundary Layer Transition

2015

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The effect of geometric forward-facing steps on boundary layer transition was experimentally investigated at a high subsonic Mach number in a blow-down wind tunnel facility in Göttingen, Germany. Boundary layer transition was detected nonintrusively by means of the Temperature-Sensitive Paint (TSP) technique. Forward-facing steps of different height were installed on a spanwise invariant wind tunnel model. Streamwise pressure gradient and high chord Reynolds number were systematically varied and their effect on boundary layer transition was studied in the presence of forward-facing steps on the model surface. At all tested stability situations, the surface imperfections were shown to reduce the extent of the laminar region. Transition was observed to move gradually towards the step location with increasing step Reynolds numbers and increasing relative step height. For a given combination of step height and chord Reynolds number, more pronounced negative pressure gradients led to an increase in transition Reynolds number. The reduction in transition Reynolds number due to the effect of the surface imperfection was more marked at larger flow acceleration. The plots of the relative change in transition location as a function of the step Reynolds number and of the relative step height gave good correlation of the results. The correlations were found to be practically independent of the streamwise pressure gradient in the examined range. Criteria for the allowable tolerances on lowsweep Natural Laminar Flow surfaces can now be derived from the functional relations determined in this work.

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Section: Experimental Setup and Definition Of Parametersmentioning

confidence: 99%

Experimental Investigation of the Effect of Forward-facing Steps on Boundary Layer Transition

2015

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“…Transition measurements were successfully made on both static (Fey et al 2006a) and rotating aerodynamic surfaces (Yorita et al 2012). TSP contains active molecules (luminophores), which are excited by a certain wavelength of light.…”

Section: Temperature-sensitive Paintmentioning

confidence: 99%

Boundary-layer transition on a rotor blade measured by temperature-sensitive paint, thermal imaging and image derotation

et al. 2015

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“…detection of "natural" transition very difficult or even impossible [28,29]. A special method for model handling and cleaning has been developed for NLF testing in the DNW-KRG wind tunnel and guarantees operation with very clean surface conditions.…”

Section: Cryogenic Ludwieg-tube Göttingenmentioning

confidence: 99%

Pressure Gradient and Nonadiabatic Surface Effects on Boundary Layer Transition

et al. 2016

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The influence of the streamwise pressure gradient and a nonadiabatic surface on boundary layer transition was experimentally investigated at the Cryogenic Ludwieg-Tube Göttingen, Germany. Boundary layer transition was detected nonintrusively by means of the temperature-sensitive paint technique. The wind-tunnel model was designed to achieve a quasi-uniform streamwise pressure gradient over a large portion of the model chord length. This allowed the effects on boundary layer transition of the streamwise pressure gradient and wall temperature ratio to be decoupled. The model was tested at high Reynolds numbers and at a high subsonic Mach number. Favorable, almostzero, and adverse streamwise pressure gradients were considered; and various temperature differences between the flow and the model surface were implemented. Stronger flow acceleration and lower wall temperature ratios led to an increase of the transition Reynolds number. Larger increases in the transition Reynolds number were obtained at more pronounced flow acceleration for the same reduction in the wall temperature ratio. The measured pressure distributions served as input for boundary layer stability computations, performed according to compressible, linear, local stability theory under the (quasi-) parallel-flow assumption. Amplification factors of the Tollmien-Schlichting waves were shown to be reduced by stronger favorable pressure gradients and lower wall temperature ratios, which was in agreement with the observed variation in the transition Reynolds number.

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High Reynolds Number Transition Detection by Means of Temperature Sensitive Paint

Cited by 37 publications

References 2 publications

Experimental Investigation of the Effect of Forward-facing Steps on Boundary Layer Transition

Experimental Investigation of the Effect of Forward-facing Steps on Boundary Layer Transition

Boundary-layer transition on a rotor blade measured by temperature-sensitive paint, thermal imaging and image derotation

Pressure Gradient and Nonadiabatic Surface Effects on Boundary Layer Transition

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