A “Cool” Thermal Tuft for Detecting Surface Flow Direction

Byerley, Aaron R.; Störmer, O.; Baughn, J. W.; Simon, Terrence W.; Treuren, Kenneth Van

doi:10.1115/1.1502631

Cited by 8 publications

(5 citation statements)

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“…The thermal boundary layer develops because of the buoyancy of the less dense air in the heated region. Byerley, et al 11 have pointed out that thermal tufts are particularly useful in vertical applications because the experimentalist does not have to worry about dripping oil from other flow visualization techniques. While this is true, the experimentalist must be aware of the effects of natural convection.…”

Section: Experimental Observations 1 Natural Convectionmentioning

confidence: 99%

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Flow Visualization with Laser-Induced Thermal Tufts

Gregory

Peterson

2005

43rd AIAA Aerospace Sciences Meeting and Exhibit

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The laser-induced thermal tuft is a new flow visualization technique for simulating traditional tufts with a thermal plume. A laser is used to heat a point of interest on a windtunnel model, causing downstream convection of thermal energy from the heated spot. A temperature-sensitive coating is used to visualize the thermal plume. This technique can be used to indicate flow direction, locate regions of separated flow, and detect laminar/turbulent transition. One primary advantage of thermal tufts is that the measurement technique is less intrusive than traditional tufts. In addition, thermal tufts may be generated at any optically-accessible point during a test, whereas string tufts must be applied to specified locations before a test. This enables greater experimental efficiency, which is particularly important in large-scale ground-testing facilities. This work extends and develops the thermal tuft concept by employing temperature-sensitive paint, as well as the previously used thermochromic liquid crystals. The effect of various substrate materials on tuft quality is evaluated. Calibrations of tuft length dependency on Reynolds number and laser power are made. Furthermore, a computational model is developed to simulate the tuft shape and structure. Finally, a new variation of the technique is presented, based on thermal ablation of the substrate material.

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Section: Experimental Observations 1 Natural Convectionmentioning

confidence: 99%

“…They also applied the technique to visualization of flow about a cylinder. Byerley et al 11 created a new variation on the technique by generating cooled thermal tufts, rather than heated spots. To accomplish this, they affixed reflective spots on a model and heated the entire model with infrared heaters.…”

Section: Introductionmentioning

confidence: 99%

Flow Visualization with Laser-Induced Thermal Tufts

Gregory

Peterson

2005

43rd AIAA Aerospace Sciences Meeting and Exhibit

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“…More recently, the development of thermal tufts has been used as a nonintrusive means of determining flow direction and separation as described by Baughn et al (1995b). The method of thermal tufts involves producing a hot or cold (i.e., Byerley et al, 2002) distance from leading edge has been coated with liquid crystal microcapsules. When exposed to a flow, the temperature distribution, displayed by the liquid crystals, appears as a tear drop shape pointing in the direction of the flow.…”

Section: Flow Visualization Techniquesmentioning

confidence: 99%

A new technique for dynamic heat transfer measurements and flow visualization using liquid crystal thermography

Ochoa

Baughn

Byerley

2005

International Journal of Heat and Fluid Flow

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“…Batchelder and Moffat [14] presented a different method of creating a heated spot by using electrically heated aluminium pins flush mounted in a carrier plate. Other techniques utilize the thermal wake of a spot that is colder than its surroundings [15][16][17][18]. Hunt and Pantoya [19,20] were the first to use the laser-thermal-tuft-technique as a quantitative tool by correlating the tuft length with the free-stream velocity.…”

Section: Introductionmentioning

confidence: 99%

A wall shear stress measurement technique using the thermal wakes of small heated spots

Rudolph¹,

Reyer²,

Nitsche³

2009

Proceedings of the Institution of Mechanical Engineers, Part G:

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A new thermo-optical method for the measurement of wall shear stresses is presented. The technique exploits that the surface temperature field and the near wall flow are closely linked by correlating the thermal wakes of small heated spots with the wall shear stress. Numerical as well as experimental results are presented and different correlation and design parameters are examined. In contrast to recent works, where the thermal tuft length is used for a correlation with the wall shear stress, other parameters were found to be much better suited for a skin friction calibration. It is also shown that the new method has the unique capability to not only measure the magnitude of the wall shear stress but also its direction.

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A “Cool” Thermal Tuft for Detecting Surface Flow Direction

Cited by 8 publications

References 0 publications

Flow Visualization with Laser-Induced Thermal Tufts

Flow Visualization with Laser-Induced Thermal Tufts

A new technique for dynamic heat transfer measurements and flow visualization using liquid crystal thermography

A wall shear stress measurement technique using the thermal wakes of small heated spots

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