Surface Oil Flow Measurements on Several Airfoils at Low Reynolds Numbers

McGranahan, Bryan D.; Selig, Michael S.

doi:10.2514/6.2003-4067

Cited by 32 publications

(14 citation statements)

References 10 publications

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“…In the drag polar plots in Fig.3, a slight increment in CD is observed at AOA=4°. McGranahan and Selig [8] identify this as "bubble drag" and it's associated with the presence of LSB. The bubble drag is larger at Re=60,000 compared to Re=100,000 which is presumably because of longer LSB.…”

Section: Force Measurementsmentioning

confidence: 95%

“…Tani [7] from his work showed that the short bubble may burst at higher AOAs causing separated flow or converting to a rather longer LSB downstream. McGranahan and Selig [8] performed oil flow visualization experiments on seven different airfoils at Re = 200,000 , 300,000 and 500,000. These airfoils included E387, FX 63-137, NASA NLF(1)-0414F, S822, S8306, SD7003, SD7307.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Flow Visualization over a Two-dimensional Airfoil at Low Reynolds Number

Shah

Kitaba

Mathew

et al. 2014

5th Brunei International Conference on Engineering and Technology (BICET 2014)

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This paper presents a set of fluid flow patterns obtained by oil flow visualization method over a low Reynolds number airfoil at angle of attack = 4°, 8°, 12° and 15°. The experiments were conducted in a low speed wind tunnel at Reynolds number = 60,000 and 100,000. The aerodynamic performance of the airfoil is also shown for direct comparison with the flow features. The experimental results showed that with increase in both the Reynolds number and the angle of attack, the extent of the laminar separation bubble diminish and at the same time progress towards the leading edge. At angle of attack ≈ 12° shorter bubble at the leading edge was found to burst and reform into a rather longer bubble causing major increase in drag values.

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Section: Force Measurementsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Experimental Flow Visualization over a Two-dimensional Airfoil at Low Reynolds Number

Shah

Kitaba

Mathew

et al. 2014

5th Brunei International Conference on Engineering and Technology (BICET 2014)

View full text Add to dashboard Cite

show abstract

“…9(d) illustrates the connection between the laminar separation bubble and the skin friction coefficient C f distribution. Laminar flow is seen to exist from the leading edge to approximately x/c = 30% because of the positive sign of C f. 16 Then separation begins at the point where C f =0 and ends where C f turns from negative to positive at x/c =50%. The flow is mainly stagnant in this region and is consistent with the so-called laminar separation bubble.…”

Section: Water Tunnel Testsmentioning

confidence: 97%

Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number

Zhao

Qiao

et al. 2015

Chinese Journal of Aeronautics

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Please cite this article as: M. Dongli, Z. Yanping, Q. Yuhang, L. Guanxiong, Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number, (2015), doi: http://dx. AbstractThis study focuses on the characteristics of low Reynolds number flow around airfoil of high-altitude unmanned aerial vehicles (HAUAVs) cruising at low speed. Numerical simulation on the flows around several representative airfoils is carried out to investigate the low Reynolds number flow. The water tunnel model tests further validate the accuracy and effectiveness of the numerical method. Then the effects of the relative thickness of airfoil on aerodynamic performance are explored, using the above numerical method, by simulating flows around airfoils of different relative thicknesses (12%, 14%, 16%, 18%), as well as different locations of the maximum relative thickness ( x/c = 22%, 26%, 30%, 34%), at a low Reynolds number of 510 5 . Results show that performance of airfoils at low Reynolds number is mainly affected by the laminar separation bubble. On the premise of good stall characteristics, the value of maximum relative thickness should be as small as possible, and the location of the maximum relative thickness ought to be closer to the trailing edge to obtain fine airfoil performance. The numerical method is feasible for the simulation of low Reynolds number flow. The study can help to provide a basis for the design of low Reynolds number airfoil.

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“…Nonetheless, this code is not always accurate for other airfoils analyzed at low Reynolds numbers. In particular, it does not always predict the location of turbulent separation accurately as shown by McGranahan and Selig [66], which can result in significant discrepancies in JERT-14-1403, Van Treuren drag prediction. Additionally, neither of these codes predicts post-stall performance accurately, which is extremely important for stall-controlled blades.…”

mentioning

confidence: 89%

Small-Scale Wind Turbine Testing in Wind Tunnels Under Low Reynolds Number Conditions

Treuren

2015

Journal of Energy Resources Technology

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Much of the aerodynamic design of wind turbines isaccomplished using computational tools such as XFOIL. These codes are not robust enough for predicting performance under the low Reynolds numbers found with small-scale wind turbines. Wind tunnels can experimentally test wind turbine airfoils to determine lift and drag data over typical operating Reynolds numbers. They can also test complete small wind turbine systems to determine overall performance. For small-scale wind turbines, quality experimental airfoil data at the appropriate Reynolds numbers are necessary for accurate design and prediction of power production. A c c e p t e d M a n u s c r i p t N o t C o p y e d i t e dDownloaded From: http://energyresources.asmedigitalcollection.asme.org/ on 05/23/2015 Terms of Use: http://asme.org/terms

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Surface Oil Flow Measurements on Several Airfoils at Low Reynolds Numbers

Cited by 32 publications

References 10 publications

Experimental Flow Visualization over a Two-dimensional Airfoil at Low Reynolds Number

Experimental Flow Visualization over a Two-dimensional Airfoil at Low Reynolds Number

Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number

Small-Scale Wind Turbine Testing in Wind Tunnels Under Low Reynolds Number Conditions

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