Journal ArticleDOI
Control of circular cylinder flow by the use of dimples
P.W. Bearman,John K. Harvey +1 more
TLDR
In this paper, the Strouhal number of a dimpled circular cylinder over the Reynolds number range from 2 x 104 to 3 x 10s is reported. And the ratio of the depth of the dimples to the diameter of the cylinder is 9xlO~ 3.Abstract:
Measurements are reported of the drag coefficient and Strouhal number of a dimpled circular cylinder over the Reynolds number range from 2 x 104 to 3 x 10s. The ratio of the depth of the dimples to the diameter of the cylinder is 9xlO~ 3. In common with sand-roughened cylinders, the dimpled cylinder has a lower critical Reynolds number than a smooth cylinder. After the drag coefficient minimum, the CD does not rise to the high values that are typical of cylinders with sand roughness but is found to be closer to that for a smooth cylinder. Over a Reynolds number range from about 4xl04 to 3xl05, a dimpled circular cylinder has a lower drag coefficient than a smooth cylinder.read more
Citations
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Journal ArticleDOI
Control of Flow Over a Bluff Body
TL;DR: In this paper, the authors present control methods for flow over a bluff body such as a circular cylinder, a 2D bluff body with a blunt trailing edge, and a sphere.
Journal ArticleDOI
Comparison of Heat Transfer Augmentation Techniques
TL;DR: Ligrani et al. as mentioned in this paper investigated the effects of surface roughness on turbulent boundary layers, transitional phenomena in curved channels, and innovative schemes for internal cooling and surface heat transfer augmentation, such as dimpled surfaces and swirl chambers, as well as a variety of gas turbine heat transfer and blade cooling problems.
Journal ArticleDOI
Flow structure due to dimple depressions on a channel surface
TL;DR: In this article, the authors described the instantaneous, dynamic and time-averaged characteristics of the vortex structures which are shed from the dimples placed on one wall of a channel.
Journal ArticleDOI
Local Heat Transfer and Flow Structure on and Above a Dimpled Surface in a Channel
TL;DR: In this article, the authors measured the Reynolds numbers from 1,250 to 61,500 and ratios of air inlet stagnation temperature to surface temperature ranging from 0.68 to 0.94.
Journal ArticleDOI
Mechanism of drag reduction by dimples on a sphere
TL;DR: In this paper, a detailed mechanism of drag reduction by dimples on a sphere such as golf-ball dimples by measuring the streamwise velocity above the dimpled surface was presented. But the authors did not consider the effect of the surface surface on the main separation.
References
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Journal ArticleDOI
Influence of surface roughness on the cross-flow around a circular cylinder
TL;DR: In this article, the influence of surface roughness on the cross-flow around a circular cylinder is investigated in a high-pressure wind tunnel, thus high Reynolds numbers up to Re = 3 × 106 could be obtained.
Journal ArticleDOI
On vortex shedding from a circular cylinder in the critical Reynolds number régime
TL;DR: In this article, the flow around a circular cylinder has been examined over the Reynolds number range 105 to 7·5 × 105, Reynolds number being based on cylinder diameter, and Narrow-band vortex shedding has been observed up to a Reynolds number of 5·5× 105, i.e. well into the critical regime.
Journal ArticleDOI
The effects of surface roughness and tunnel blockage on the flow past spheres
TL;DR: In this article, the effect of surface roughness on the flow past spheres has been investigated over the Reynolds number range 5 × 104 < Re < 6 × 106, where the Strouhal number for each of the various roughness conditions was equal to its value for a smooth sphere.
Journal ArticleDOI
Golf Ball Aerodynamics
P.W. Bearman,John K. Harvey +1 more
TL;DR: In this paper, a wind tunnel technique has been developed to measure the aerodynamic forces acting on golf balls over a wide range of Reynolds number and spin rate, and balls with round and hexagonal dimples have been investigated.
Wall interference in a two-dimensional-flow wind tunnel, with consideration of the effect of compressibility
H Julian Allen,Walter G Vincenti +1 more
TL;DR: Theoretical tunnel-wall corrections for an airfoil of finite thickness and camber in a two-dimensional flow wind tunnel were derived in this article, and the results were compared with the small amount of low-speed experimental data available, even for relatively large values of the chord-height ratio.