Riblets as a Viscous Drag Reduction Technique

Walsh, Michael J.

doi:10.2514/3.60126

Cited by 484 publications

(251 citation statements)

References 2 publications

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“…Electron beam processed surface textures on titanium alloys were demonstrated to be efficient for drag reducing in the turbulent-flow regime [1][2][3][4]. A fluid-drag reduction efficient over 15% was achieved by introducing electron beam processed surface textures aligned in the flow direction on a Ti-6Al-4V alloy [4].…”

Section: Introductionmentioning

confidence: 98%

Formation Mechanisms of Electron Beam Processed Surface Textures on Titanium Alloys

Li¹,

Fu²,

Wu³

et al. 2017

Proceedings of the Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017)

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Abstract. The electron beam processed surface textures on a Ti-6Al-4V ally and a Ti-4Al-1.5Mn alloy were examined by using advanced optical microscopy for surface morphology analysis and near-surface microstructure observation. It showed that the as-resulted non-smooth surface was characterized by parallel ridges and grooves, with height and spacing closely related to processing parameters. The ridges displayed successive scale shaped features while the valley of grooves presented V shaped ripples. Based on a comprehensive observation, the formation mechanisms of such electron beam processed surface textures were discussed. In addition, the near-surface region of electron beam processed titanium alloys were characterized by fusion zone, heat affected zone and base metal from the outermost surface to the underlying base metal. The fusion zone was dominated by martensite phase generated in a high cooling rate. A heat affect zone was sandwiched between fusion zone and the underlying base metal, with different microstructural features compared to both fusion zone and base metal. The microstructure gradient is closely related to the heat distribution from the high energy electron beam.

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Section: Introductionmentioning

confidence: 98%

Formation Mechanisms of Electron Beam Processed Surface Textures on Titanium Alloys

Li¹,

Fu²,

Wu³

et al. 2017

Proceedings of the Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017)

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“…Walsh & Weinstein (1979) were among the first to examine this technique, and it has been examined in numerous other studies (e.g., Walsh 1983;Johansen & Smith 1986;Lazos & Wilkinson 1988;Choi 1989Choi , 1993Pollard 1997). Drag reductions on the order of 8% have been demonstrated in laboratory experiments and in direct numerical simulations, however the precise mechanism by which the wall shear stress reduction occurs remains a subject of some controversy.…”

Section: Active Sublayer Controlmentioning

confidence: 99%

Electrokinetic Microactuator Arrays for Control of Vehicles

Diez-Garcia¹,

Dahm²

2002

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“…Nowadays it is well known that certain surface structures, like e.g. riblets aligned in the flow direction, can also reduce the friction drag [3], [20], [22]. The most prominent example in this case are riblets which provide a drag reduction of up to maximum 10% [2], [5] under laboratory conditions.…”

Section: Introductionmentioning

confidence: 99%

Drag Evaluations on Rough Surfaces From Near-Wall Models

Friedmann¹,

Kim²,

Ri³

2017

Topical Problems of Fluid Mechanics 2017

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In this paper we evaluate the drag of periodic rough microstructures from near-wall models. With near-wall models we denote Coutte flows which describe the viscous boundary layer of turbulent flows. The structures inside this layer are not the optimal ones but can be used for a deeper understanding of the drag reducing mechanism of riblets due to a valid mathematical theory for viscous flows. Here, the numerical calculations can be validated and the developed calculation strategies can later be extended to the turbulent boundary layer. The focus of this paper is the evaluation of the drag of several microstructures for a better understanding of their action to the turbulent overflow. The influence of the structures will be visible trough a shift in the mean velocity profile which will be quantified. Due to the fixed calculation domain and thus an altered sublayer thickness, the obtained drag values can not be easily compared. We will as well present a theory for the comparison of the drag of rough surfaces calculated from our near-wall models as one for the comparison of rough versus smooth surface.

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Riblets as a Viscous Drag Reduction Technique

Cited by 484 publications

References 2 publications

Formation Mechanisms of Electron Beam Processed Surface Textures on Titanium Alloys

Formation Mechanisms of Electron Beam Processed Surface Textures on Titanium Alloys

Electrokinetic Microactuator Arrays for Control of Vehicles

Drag Evaluations on Rough Surfaces From Near-Wall Models

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