Relevant bibliographies by topics / Riblets

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Riblets'

Author: Grafiati
Published: 4 June 2021
Last updated: 8 February 2022

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Journal articles on the topic "Riblets"

1

West, Nathan, Karl Sammut, and Youhong Tang. "Material selection and manufacturing of riblets for drag reduction: An updated review." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 232, no. 7 (April 1, 2016): 610–22. http://dx.doi.org/10.1177/1464420716641452.

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Riblets are a well-researched and understood passive method for achieving viscous drag reduction. Since the 1970s, researchers have found that, with riblets, viscous drag reduction in the order of 8% is achievable in turbulent air and fluid flows. Most of the relevant literature provides insight into the drag-reductive mechanisms of riblets and the effect of riblet morphological design in varying flow conditions. A few recent studies have begun to investigate the influence of material properties on the drag-reductive ability of riblet surfaces with promising results. We here provide an updated review of material selection and riblet manufacture and show current trends. A brief summary is provided of the theories of riblet drag-reductive ability, riblet surface design, the role of material selection for drag reduction and current manufacturing techniques.
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Bai, Xiuqin, Xuan Zhang, and Chengqing Yuan. "Numerical Analysis of Drag Reduction Performance of Different Shaped Riblet Surfaces." Marine Technology Society Journal 50, no. 1 (January 1, 2016): 62–72. http://dx.doi.org/10.4031/mtsj.50.1.9.

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AbstractAiming to investigate the drag reduction performance of an antifouling shell rough surface, six different geometries of shell surface texture are simplified as V-shaped riblet, U-shaped riblet, space-V-shaped riblet, blunt-V-shaped riblet, L-shaped riblet, and ∩-shaped riblet. Five kinds of riblets have the same geometric features: groove height and grooved spacing. SST-k-ω model is adopted for the turbulence model. The flow field structure above the different shaped riblet surfaces as well as shear stress and turbulent kinetic energy are analyzed. Moreover, how the flow is influenced by different shapes of riblets is discussed. The knowledge gained in this study can provide theoretical reference for optimal groove surface design of a ship hull with drag reduction performance.
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Goldstein, D., R. Handler, and L. Sirovich. "Direct numerical simulation of turbulent flow over a modeled riblet covered surface." Journal of Fluid Mechanics 302 (November 10, 1995): 333–76. http://dx.doi.org/10.1017/s0022112095004125.

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An immersed boundary technique is used to model a riblet covered surface on one wall of a channel bounding fully developed turbulent flow. The conjecture that the beneficial drag reduction effect of riblets is a result of the damping of cross-flow velocity fluctuations is then examined. This possibility has been discussed by others but is unverified. The damping effect is explicitly modelled by applying a cross-flow damping force field in elongated streamwise zones with a height and spacing corresponding to the riblet crests. The same trends are observed in the turbulence profiles above both riblet and damped surfaces, thus supporting cross-flow damping as a beneficial mechanism. It is found in the examples presented that the effect of the riblets on the mean flow field quantities (mean velocity profile, velocity fluctuations, Reynolds shear stress, and low–speed sreak spacing) is small. The riblests cause a relatively small drag reduction of about 4%, a figure that is in rough agreement with experiments and other computations. The simulations also suggest a mechanism for the observed displacement of the turbulence quantities away from the wall.The immersed boundary technique used to model the riblets consists of creating an externally imposed spatially localized body force which opposes the flow velocity and creates a riblet-like surface. For unstead viscous flow the calculation of the force is done with a feedback scheme in which the velocity is used to iteratively determine the desired value. In particular, the surface body force is determined by the relation f(xs, t) = α ∫ t0U(xs,t′)dt′ + βU(xs, t) for surface points xs, velocity U time t and negative constants α and β. All simulations are done with a spectral code in a single computational domain without any mapping of the mesh. The combination of the immersed boundary and spectral techniques can potentially be used to solve other problems having complex geometry and flow physics.
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García-Mayoral, Ricardo, and Javier Jiménez. "Drag reduction by riblets." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1940 (April 13, 2011): 1412–27. http://dx.doi.org/10.1098/rsta.2010.0359.

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The interaction of the overlying turbulent flow with riblets, and its impact on their drag reduction properties are analysed. In the so-called viscous regime of vanishing riblet spacing, the drag reduction is proportional to the riblet size, but for larger riblets the proportionality breaks down, and the drag reduction eventually becomes an increase. It is found that the groove cross section A + g is a better characterization of this breakdown than the riblet spacing, with an optimum . It is also found that the breakdown is not associated with the lodging of quasi-streamwise vortices inside the riblet grooves, or with the inapplicability of the Stokes hypothesis to the flow along the grooves, but with the appearance of quasi-two-dimensional spanwise vortices below y + ≈30, with typical streamwise wavelengths . They are connected with a Kelvin–Helmholtz-like instability of the mean velocity profile, also found in flows over plant canopies and other surfaces with transpiration. A simplified stability model for the ribbed surface approximately accounts for the scaling of the viscous breakdown with A + g .
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Zhang, Yufei, and Yuhui Yin. "Study on Riblet Drag Reduction Considering the Effect of Sweep Angle." Energies 12, no. 17 (September 2, 2019): 3386. http://dx.doi.org/10.3390/en12173386.

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This study computationally evaluates the riblet drag reduction effect considering the effect of sweep angle. An implicit large eddy simulation is performed on a channel flow and an infinite swept wing. First, three different inclined angles between the riblets and the flow direction are tested in the channel flow. The results show that with increases in the inclined angle, the friction drag decreases, while the pressure drag increases approximately quadratically. The riblets with a 30° inclined angle increase the total drag of the channel flow. Then, an infinite wing with a 30° swept angle with and without riblets is studied. The riblets demonstrate satisfactory drag reduction efficiency because the cross flow over most parts of the wing is mild. The lift and friction drag follow the relation of the cosine law of a swept wing. Moreover, the cross flow and the turbulence fluctuation are suppressed by the riblets.
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Yang, Yu, Zhang Ming-Ming, and Li Xue-Song. "Numerical investigation of V-shaped riblets and an improved model of riblet effects." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 9 (April 24, 2017): 1622–31. http://dx.doi.org/10.1177/0954406217705907.

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Symmetric V-shaped riblets are simulated by using the computational fluid dynamic method to understand the riblet effects on the turbulent boundary layer and the skin friction reduction. Three classical turbulence models, namely Spalart–Allmaras, shear stress transport, and re-normalization group k-epsilon models, are investigated under different grid densities. The re-normalization group model produces good results consistent with the experiment, as compared with the existing theoretical and experimental drag results of the flat plate and the V-shaped riblets with different sizes. Simulating V-shaped riblets yield the unexpected discovery that the shear stress transport model produces large errors, and the Spalart–Allmaras model even produces results of qualitative errors. Another finding is that von Kármán’s constants can no longer meet the requirement of describing velocity profiles in the logarithmic law layer. Aside from the traditional shift of the logarithmic law’s intercept, the slope is also changed by riblet height and spacing. Therefore, an improved model of riblet effects is proposed by redefining von Kármán’s constants.
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Zhang, Zi-Liang, Ming-Ming Zhang, Chang Cai, and Yu Cheng. "Characteristics of large- and small-scale structures in the turbulent boundary layer over a drag-reducing riblet surface." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 3 (November 13, 2019): 796–807. http://dx.doi.org/10.1177/0954406219887774.

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Riblet is one of the most promising passive drag reduction techniques in turbulent flows. In this paper, hot-wire measurements on a turbulent boundary layer perturbed by a drag-reducing riblet surface are carried out to further understand the riblet effects on the turbulent flows and the drag reduction mechanism. Compared with the smooth case, different energy variations in the near-wall region and the logarithmic region are observed over riblets. Then, by using a spectral filter of a given wavelength, the time series of the hot-wire data are decomposed into large- and small-scale components. It is indicated that large-scale structures in the logarithmic region impose a footprint (amplitude modulating effect) on the near-wall small-scale structures. By quantifying this footprint, it is found that the interactions between large- and small-scale structures over riblets are weakened in the near-wall region. Furthermore, the bursting process of large and small scales is studied. For both large- and small-scale structures, a shorter bursting duration and a higher bursting frequency are observed over the riblet surface, which indicates that riblets impede the formation of large- and small-scale bursting events. The flow physics behind these phenomena are also discussed in detail.
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Radmanesh, Mohammadreza, Iman Samani, Alireza Amiriyoon, and Mohammad-Reza Tavakoli. "The effects of rectangular riblets on rectangular micro air vehicles for drag reduction." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 2 (August 6, 2016): 364–73. http://dx.doi.org/10.1177/0954410016638868.

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Reduced drag, increased lift and, consequently, increased vital ratio and lift-to-drag coefficients are crucial in almost all efficient micro air vehicles. Riblet geometries use a variety of air vehicles. Further investigation on micro air vehicles is, however, necessary for enhanced development. Rectangular riblets on a rectangular micro air vehicle are computationally investigated. In this study, the governing equation of fluid flow is solved numerically; the turbulent model around the NACA S5020 airfoil section is covered by riblets either on both sides or on the upper side of the wings. Results show a difference of behavior in drag reduction due to the angle of attack on the airfoil. When the lift-to-drag coefficient of an angle of attack is at its maximum, an improvement can be observed, where lift-to-drag ratio increases, and drag decreases. Results for the two-side riblets show an increase in the lift-to-drag ratio as well; although the lift-to-drag coefficient and the drag reduction of riblets on both sides were comparatively less than that for riblets on the upside.
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Denkena, Berend, Thilo Grove, and Jan Harmes. "Grinding of Riblets on Curved Paths." Materials Science Forum 874 (October 2016): 28–33. http://dx.doi.org/10.4028/www.scientific.net/msf.874.28.

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The grinding of riblets with multiple profiled grinding wheels is an efficient method to minimize the fluid friction on surfaces. In turbo machinery components, like pump impellers or compressor blades, the riblets must be ground with a curved tool path since the flow is rarely linear on such surfaces. This leads to angular errors in the generated riblet profiles and therefore requires the use of grinding wheels with smaller diameters. The tool wear increases due to lateral strain on the peaks of the grinding wheel. Consequently, the increased wear and the need of smaller tool diameters decrease the efficiency of the process. In this paper a structuring process with dicing blades was investigated in order to increase the economic viability of this process. A dressing operation for such tools is not necessary and thus reduces the non-productive time of the manufacturing process. Furthermore, profile tip wear has no negative effects on the aspect ratio of the generated riblets since the riblet geometry is determined by the thickness of the dicing blades.
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Dean, Brian, and Bharat Bhushan. "Shark-skin surfaces for fluid-drag reduction in turbulent flow: a review." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1929 (October 28, 2010): 4775–806. http://dx.doi.org/10.1098/rsta.2010.0201.

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The skin of fast-swimming sharks exhibits riblet structures aligned in the direction of flow that are known to reduce skin friction drag in the turbulent-flow regime. Structures have been fabricated for study and application that replicate and improve upon the natural shape of the shark-skin riblets, providing a maximum drag reduction of nearly 10 per cent. Mechanisms of fluid drag in turbulent flow and riblet-drag reduction theories from experiment and simulation are discussed. A review of riblet-performance studies is given, and optimal riblet geometries are defined. A survey of studies experimenting with riblet-topped shark-scale replicas is also given. A method for selecting optimal riblet dimensions based on fluid-flow characteristics is detailed, and current manufacturing techniques are outlined. Due to the presence of small amounts of mucus on the skin of a shark, it is expected that the localized application of hydrophobic materials will alter the flow field around the riblets in some way beneficial to the goals of increased drag reduction.
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Dissertations / Theses on the topic "Riblets"

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Oehlert, Karsten [Verfasser]. "Zur Applikation von Riblets auf Verdichterschaufeln / Karsten Oehlert." München : Verlag Dr. Hut, 2011. http://d-nb.info/1014848598/34.

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Lietmeyer, Christoph [Verfasser]. "Berechnungsmodell zur Widerstandsbeeinflussung nicht-idealer Riblets auf Verdichterschaufeln / Christoph Lietmeyer." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1070286427/34.

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Raayai, Ardakani Shabnam. "Geometry mediated drag reduction using riblets and wrinkled surface textures." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115612.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 281-291).
The surfaces of many plants and animals are covered with a variety of micro-textures such as ribs or 3D tubules which can control surface-mediated properties such as skin friction. Inspired by the drag reducing ability of these natural structures, especially the ribbed features on shark denticles, passive drag reduction strategies such as micro-fabricated riblet surfaces have been developed and studied. Microgroove textures on the surface of objects such as hulls, wings or inner surface of pipes which are aligned in the stream-wise direction have been shown to reduce the wall friction by 4 - 8%. The mechanisms suggested for this form of drag reduction are viscous retardation of the flow in the grooves (both laminar and turbulent) and the displacement of vortical structures away from the wall in turbulent flows. Due to their effectiveness in altering the boundary layer structure and reducing the viscous drag force, use of riblets have been banned in various competitions such as the America's Cup. The current thesis work is partly focused on theoretical and numerical modelling (using the open source CFD package OpenFOAM) of the evolution of viscous boundary layers in the presence of various-shaped riblets (V-grooves as well as sinusoidal wrinkled surfaces) in high Reynolds laminar flow. We explore the effect of the dimensionless height to spacing of the grooves (aspect ratio) as well as the length of the wetted surface in the streamwise direction and how these change the total drag compared with a corresponding flat wall. We show that riblets retard the viscous flow inside the grooves and reduce the shear stress inside the grooves. But for this reduction to result in overall drag reduction, the riblet wall needs to be longer than a critical length. The total drag reduction achieved is a non-monotonic function of the aspect ratio of the riblets, with aspect ratios of order unity offering the largest reduction in the total drag. To eliminate the role of entrance effects, we additionally investigate the effect of stream-wise aligned riblet structures on fully-developed Taylor-Couette flow. We perform both experimental studies as well as time-dependent numerical simulations in both the laminar Couette and the Taylor vortex regime. We again explore the effect of the size of the riblets with respect to the geometry of the Taylor-Couette cell, as well as the aspect ratio of the riblet grooves and the shape of the grooves (V-groove, Rectangular, semi-circular, etc.). For the experiments, the cylindrical textured rotors are fabricated using 3D printing techniques and the rest of the Taylor-Couette cell is custom built using CNC machining. The test cell is then aligned and mounted on a stress-controlled rheometer to measure the velocity and the torque on the rotating inner cylinder. The numerical studies are performed using the open source CFD software package OpenFOAM to compare results and understand the physical mechanisms contributing to this drag reduction phenomenon. Again we observe a non-monotonic behavior for the reduction in torque as a function of the aspect ratio of the riblets tested, similar to the trend observed in the boundary layer analysis and we discuss the effect of changing the geometry of the flow as well as the riblet spacing on the changes in the total torque. When viewed holistically the results of these two studies show that, through careful design, a net reduction in viscous drag force can be robustly realized on micro-textured surfaces in high Reynolds number laminar flows through complex changes in near-wall stream-wise velocity profiles even in the absence of turbulent effects. The understanding of these changes can be effective in guiding the design of internal flows (pipes or ducts) and external flows (such as ship hulls, micro air vehicles or unmanned underwater vehicles) that are tailored and optimized to result in low frictional drag over the entire wetted surface in both laminar and turbulent regions.
by Shabnam Raayai Ardakani.
Ph. D.
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Rutledge, Jeffrey. "Direct simulation of enhancement of turbulent heat transfer by micro-riblets /." Thesis, Connect to this title online; UW restricted, 1989. http://hdl.handle.net/1773/9839.

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Starling, Iain. "The use of riblets for delaying boundary layer transition to turbulence." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263407.

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Orchard, D. M. "The near-wall structure of the thermal turbulent boundary layer over riblets." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339557.

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Sayad, Saravi Samira. "An investigation on design and analysis of micro-structured surfaces with application to friction reduction." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/8559.

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Drag reduction in wall-bounded flows can be achieved by the passive flow control technique using riblets and surface grooves aligned in the mean direction of an overlying turbulent flow. They were inspired by the skin of fast sharks covered with small longitudinal ribs on their skin surfaces. Although it was found that the drag reduction depends on the riblets’ geometrical characteristics, their physical mechanisms have not yet been fully understood in the scientific terms. Regarding riblets sizing, it has been critically explained in the literature how riblets with vanishing size interact with the turbulent flow and produce a change in the drag proportional to their size. Their shapes are focused upon because these are most significant from a technological perspective, and also less well understood. Different riblet shapes have been designed, some with complicated geometries, but except for the simple ones, such as U and V grooves, there has not been enough study regarding shape features. Therefore, special effort is undertaken to the design of an innovative type of ribleted surface, e.g. the Serrate-Semi-Circular shape, and its effect on the skin friction and drag reduction. In this work, the possible physical mechanisms of riblets for turbulent drag reduction have been explored. The modelling and experiments concerning the relationship between the riblets features and the turbulent boundary layer structure have also been reviewed. Moreover, numerical simulations on riblets with different shapes and sizes are presented and studied in detail. An accurate treatment based on k-ε turbulence model was adopted to investigate the flow alteration and the consequent drag reduction on ribleted surfaces. The interaction of the overlying turbulent flow with riblets and its impact on their drag reduction properties are further investigated. In addition, the experimental facilities, instrumentation (e.g. hotwires) and measurement techniques (e.g. time-averaged turbulence structure) have been employed to experimentally investigate the boundary layer velocity profiles and skin friction for smooth and micro-structured surfaces (the proposed riblet shape, respectively and the presented new design of riblets with serration inside provides 7% drag reduction. The results do not show significant reduction in momentum transfer near the surface by riblets, in particular, around the outer region of the turbulent boundary layer. Conclusions with respect to the holistic investigation on the drag reduction with Serrate-Semi-Circular riblets have been drawn based on the research objectives as achieved. Recommendations for future work have been put forward particularly for further future research in the research area.
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Perkins, Richard Mark. "PIV Measurements of Turbulent Flow in a Rectangular Channel over Superhydrophobic Surfaces with Riblets." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5547.

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In this thesis I investigate characteristics of turbulent flow in a channel where one of the walls has riblets, superhydrophobic microribs, or a hybrid surface with traditional riblets built on a superhydrophobic microrib surface. PIV measurements are used to find the velocity profile, the turbulent statistics, and shear stress profile in the rectangular channel with one wall having a structured test surface. Both riblets and superhydrophobic surfaces can each provide a reduction in the wall shear stress in a turbulent channel flow. Characterizing the features of the flow using particle image velocimetry (PIV) is the focus of this research. Superhydrophobicity results from the combination of a hydrophobic coating applied to a surface with microrib structures, resulting in a very low surface energy, such that the fluid does not penetrate in between the structures. The micro-rib structures are aligned in the streamwise flow direction. The riblets are larger than the micro-rib structure by an order of magnitude and protrude into the flow. All the test surfaces were produced on silicon wafers using photolithographic techniques. Pressure in the channel is maintained below the Laplace pressure for all testing, creating sustainable air pockets between the microribs. Velocity profiles, turbulent statistics, shear stress profiles, and friction factors are presented. Measurements were acquired for Reynolds numbers ranging from 4.5x10^3 to 2.0x10^4. Modest drag reductions were observed for the riblet surfaces. Substantial drag increase occurred over the superhydrophobic surfaces. The hybrid surfaces showed the greatest drag reduction. Turbulence production was strongly reduced during riblet and hybrid tests.
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Ninnemann, Todd A. "Effects of riblets on the performance of the supersonic through-flow fan cascade blades." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/29358.

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An experimental study to determine the effects of riblets on the performance of the supersonic through-flow fan (STF) cascade blades was performed. The two-dimensional cascade was tested in the Virginia Polytechnic Institute and State University intermittent wind tunnel facility, where the Mach and Reynolds (based on chord) numbers were 2.36 and 4.8 x 10⁶ , respectively. Three different V-grooved riblet heights were tested on the blades: 0.023, 0.033, and 0.051 mm. Riblet testing were conducted at design incidence as well as at off-design conditions (incidence angles: +5, -10 deg). The riblet effect on the performance of the STF blades was determined by measuring the total pressure profile downstream of the cascade and integrating this total pressure to obtain an overall mass-averaged loss coefficient. The riblet loss coefficient was compared with the loss coefficient of a control test case where an equivalent thickness of smooth material is applied to the blades. Results show that, at the design incidence, the 0.033 mm height riblets provided the optimal benefit, with a reduction of 8.5% in the loss coefficient compared to the control case. Smaller effects were measured at the off-design conditions. Shadowgraph pictures were taken to study the effect of riblets on the turbulent transition location on the blades surfaces. At design incidence, the shadowgraphs revealed that the optimum height rib lets delayed the transition location on the suction surface of the blades. Therefore, it was concluded that for the 0.033 mm height riblets the decrease in the cascade's loss coefficient was the result of delayed transition in addition to a decrease in turbulent viscous losses. A numerical simulation was conducted to investigate both rib let effects on the STF blades. The numerical study showed that only the combination of the two riblet effects was able to produce a decrease in loss coefficient that was observed experimentally. Results from the numerical study indicate, that at design incidence, 2/3 of the rib let benefit is attributed to the delayed transition effect on the blades with the other 1/3 resulting from a decrease in turbulent viscous losses.
Ph. D.
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Pulvin, Philippe. "Contribution à l'étude des parois rainurées (riblets) pour les écoulements internes avec gradient de pression positif /." Lausanne, 1989. http://library.epfl.ch/theses/?nr=809.

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Books on the topic "Riblets"

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Khalid, M. Use of riblets to obtain drag reduction on airfoils at high Reynolds number flows. Ottawa: National Aeronautical Establishment, National Research Council Canada, 1988.

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Bouabid, Abdelhamid. Herstellung metallisch gebundener Schleifscheiben für das Schleifen von Riblets. Wiesbaden: Springer Fachmedien Wiesbaden, 2015. http://dx.doi.org/10.1007/978-3-658-09909-1.

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Dantini, Michèle. Le muse e l'Arcadia: Fernand Riblet (1873-1944) : tra simbolismo, post-impressionismo, e liberty. Milano: E. & S. Guastalla, 1995.

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Flight test results of riblets at supersonic speeds. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1992.

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Bouabid, Abdelhamid. Herstellung metallisch gebundener Schleifscheiben für das Schleifen von Riblets. Springer Vieweg, 2015.

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Effects of Pressure Gradients on Turbulent Boundary Layer Flow Over a Flat Plate with Riblets. Storming Media, 1999.

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A, Musick John, Langley Research Center, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., eds. Hydrodynamic aspects of shark scales. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1986.

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Wells, Martin. Tramway Titan: Byron Riblet, Wire Rope And Western Resource Towns. Trafford, 2005.

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Riblet Effects on Gortler Vortex Development Over a Concave Surface. Storming Media, 1996.

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Riley, Stanley. RIBLS: Riley inventory of basic learning skills manual. Academic Therapy Publications, 1992.

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Book chapters on the topic "Riblets"

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Kwon, Jae-Sung, Raviraj Thakur, Steven T. Wereley, J. David Schall, Paul T. Mikulski, Kathleen E. Ryan, Pamela L. Keating, et al. "Riblets." In Encyclopedia of Nanotechnology, 2238. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-90-481-9751-4_100712.

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Gyr, A. "Natural Riblets." In IUTAM Symposium on Mechanics of Passive and Active Flow Control, 109–14. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4199-4_18.

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Pironneau, O., and G. Arumugam. "On riblets in laminar flows." In Control of Boundaries and Stabilization, 51–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/bfb0043352.

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Bouabid, Abdelhamid. "Untersuchungen zum Schleifen von Riblets." In Herstellung metallisch gebundener Schleifscheiben für das Schleifen von Riblets, 89–92. Wiesbaden: Springer Fachmedien Wiesbaden, 2015. http://dx.doi.org/10.1007/978-3-658-09909-1_8.

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Choi, K. S., and S. Hamid. "Heat transfer study of riblets." In Recent Developments in Turbulence Management, 25–41. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3526-9_2.

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Hage, W., D. W. Bechert, and M. Bruse. "Yaw Angle Effects on Optimized Riblets." In Aerodynamic Drag Reduction Technologies, 278–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-540-45359-8_29.

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Choi, Kwing-So, and Shamim Hamid. "Near-Wall Turbulence Structure over Misaligned Riblets." In Advances in Turbulence 3, 464–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-84399-0_50.

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Liu, K. N., C. Christodoulou, O. Riccius, and D. D. Joseph. "Drag Reduction in Pipes Lined with Riblets." In Structure of Turbulence and Drag Reduction, 545–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-50971-1_45.

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Zhou, Jian, Ping Ou, and Wei Wei. "Modeling of Turbulence Drag Reduction with Riblets." In Lecture Notes in Electrical Engineering, 614–29. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3305-7_50.

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10

Augenstein, E., F. Leopold, F. Christnacher, and E. Bacher. "Influence of Riblets on a Supersonic Wake Flow." In IUTAM Symposium on Mechanics of Passive and Active Flow Control, 145–50. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4199-4_24.

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Conference papers on the topic "Riblets"

1

Lietmeyer, Christoph, Karsten Oehlert, and Joerg R. Seume. "Optimal Application of Riblets on Compressor Blades and Their Contamination Behavior." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46855.

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During the last decades, riblets have shown a potential for viscous drag reduction in turbulent boundary layers. Several investigations and measurements of skin-friction in the boundary layer over flat plates and on turbomachinery type blades with ideal riblet geometry have been reported in the literature. The question where riblets must be applied on the surface of a compressor blade is still not sufficiently answered. In a first step, the profile loss reduction by ideal triangular riblets with a trapezoidal groove and a constant geometry along the surface on the suction and pressure side of a compressor blade is investigated. The results show a higher potential on the profile loss reduction by riblets on the suction side. In a second step, the effect of laser-structured ribs on the laminar separation bubble and the influence of these structures on the laminar boundary layer near the leading edge are investigated. After clarifying the best choices where riblets should be applied on the blade surface, a strategy for locally adapted riblets is presented. The suction side of a compressor blade is laser-structured with a segmented riblet-like structure with a constant geometry in each segment. The measured profile loss reduction shows the increasing effect on the profile loss reduction of this locally adapted structure compared to a constant riblet-geometry along the surface. Furthermore, the particle deposition on a riblet-structured compressor blade is investigated and compared to the particle deposition on a smooth surface. Results show a primary particle deposition on the riblet tips followed by an agglomeration. The particle deposition on the smooth surface is stochastic.
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2

Oehlert, Karsten, and Joerg R. Seume. "Exploratory Experiments on Machined Riblets on Compressor Blades." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98093.

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During the last decades, riblets have shown a potential for viscous drag reduction. Several investigations and measurements of skin-friction have been completed in the boundary layer over a flat plate carrying riblets, mostly on thin foils. The purpose of the present study is to investigate machined riblet structures which are fabricated by grinding and laser machining. First tests dealing with machined riblets on flat plates are presented in this paper. Future investigations will examine the aerodynamic behaviour of machined riblets on NACA compressor blades. The specimens, flat plates and compressor blades, are tested in a linear cascade wind tunnel. Perfect trapezoidal riblets have been designed specifically to the flow parameters in this wind tunnel. Foils carrying the ideal riblets provide a basis for comparison with the riblets created by grinding and by laser machining. Parameters describing the geometry and the deviation from ideal riblets have been developed. It turned out that it is quite difficult to produce riblets satisfying the ideal geometrical requirements by machining. However, measurements in the wake of flat plates show that the laser shaped riblets as well as the ground riblets reduce pressure loss coefficients by up to 3.6%.
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3

Klumpp, Stephan, Matthias Meinke, Wolfgang Schro¨der, Bjo¨rn Feldhaus, and Fritz Klocke. "Riblets in Turbulent Flow Regimes of 2-D Compressor Blades." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59352.

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The application of riblets to compressor blades is investigated. A rolling technique is developed which is able to produce riblets on the surface of titanium alloy workpieces and possesses several advantages concerning the durability of the final blade. The rolling process generates a strain hardening of the rim zone and a deformation of the micro structure which improves the durability of the riblets. Furthermore, compressive residual stresses are induced below the riblet valleys reducing or even compensating the extra tensile stresses caused by the notch effect during bending stress. The reduction of skin friction due to the produced riblet surface is determined by numerical flow simulations in zero-pressure gradient flow. Based on the data of a controlled diffusion airfoil (CDA) strategies to distribute riblets along the blade surface are discussed under consideration of the local shear stress. A new strategy following the idea of stepwise adapted riblets along the surface is presented. The amount of total drag reduction which could be gained by this novel strategy is estimated.
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4

Li, Zhihui, Juan Du, and Hongwu Zhang. "Physical Mechanisms Investigation of Sharkskin-Inspired Compressor Cascade Based on Large Eddy Simulations." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15209.

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Abstract In order to survive in a complex environment, nature has produced efficient and versatile resource-rich structures. One of the novel drag reduction designs comes from the efficient movement of sharks through microscope riblets aligned along the flow direction. In this paper, the effectiveness of sharkskin-inspired riblets in reducing the aerodynamic loss of compressor cascade flow was investigated by using high-fidelity numerical simulation method. Two key normalized parameters were selected to parameterize various riblet designs, and the corresponding relative change in cascade performance was first investigated based on the uRANS simulations with/without transition model. Then, the large eddy simulations in conjunction with the wall-adapted local eddy viscosity model were conducted to investigate the cascade flow with the selected riblet design cases. By comparing the flow resistance, transition positions, vortex formations and turbulence fluctuations of the boundary flow, the flow control mechanisms of the riblets were finally studied. Simulation results show that compared with the prototype case, the total pressure loss can be reduced by up to 20.5% in the fully turbulent environment. This is because the spanwise fluctuation of the turbulent vortices is impeded, and the turbulent vortices are lifted above the riblet tip. Low-speed streaks inside the riblet valleys generate relatively low shear stresses, while the high-shear stresses occur only at the riblet tips. However, when considering transition from laminar to turbulent boundary flow, the aerodynamic performance of compressor cascade strongly depends on the riblet position relative to the transition on cascade SS. The total pressure loss can only be reduced by up to 8.1%, and even most riblet designs will degrade the cascade performance. The major reason is that the riblets are located upstream of the transition zone, especially at the small incidence angles. Due to the installation of riblets, the contact area between the laminar flow and the wall surface is increased, and the downstream laminar-to-turbulent transition is promoted.
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Oehlert, Karsten, Joerg R. Seume, Frank Siegel, Andreas Ostendorf, Bo Wang, Berend Denkena, Taras Vynnyk, et al. "Exploratory Experiments on Machined Riblets for 2-D Compressor Blades." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43457.

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During the last decades, riblets have shown a potential for viscous drag reduction. Several investigations and measurements of skin-friction in the boundary layer over flat plates and on turbomachinery type blades with ideal riblet geometry have been reported in the literature. The purpose of the present study is to investigate whether laser machined and ground riblet-like structures could be successfully employed on conventional 2-D (NACA) compressor blades in order to assess the potential of industrial machining processes for the creation of the riblet effect. Perfectly trapezoid riblets were designed specifically for the flow parameters in the wind tunnel. Parameters describing the geometry and the deviation from ideal riblets are developed. Riblet machining by high precision material ablation has the potential of achieving micro-machining quality. In comparison to ns-laser processing using either Q-switched solid-state lasers or excimer lasers, the results for high precision material ablation show the enormous potential of ps-laser radiation and achieve the required quality, free of thermally induced defects and, consequently, with high reproducibility. For grinding riblets, geometrically defined microprofiles must firstly be generated via a profile dressing process and then ground onto the work piece surface. A precise adjustment of the grinding wheel system (grit, bonding) and the dressing/grinding conditions is necessary, in order to satisfy the opposing requirements at both dressing and grinding. The blade specimens were geometrically measured with a confocal microscope as well as secondary electron microscope using a specially developed riblet-oriented analysis. For verifying the measurement results, an Atomic Force Microscope was used. The specimens, i.e. flat plates and compressor blades, are aerodynamically tested in a cascade wind tunnel and properly scaled model surfaces were tested in an oil channel in order to quantify skin-friction reduction. Wake measurements of a cascade with NACA-profiles which have the resulting riblet-like structured surface show that the laser shaped as well as ground riblets reduce skin-friction almost as well as the ideal ones, which means a skin friction reduction of up to 7%.
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Fayyadh, Ekhlas M., and Nibras M. Mahdi. "Effect of Riblets Geometry on Drag Reduction." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-85228.

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The effect of longitudinal riblet surface models (U, V and semi-Circular and U with fillet corner riblets) on the performance of unsymmetrical airfoil NACA23015 which has been investigated numerically and experimentally. Numerical investigation involve examining drag reduction by solving the governing equations (Continuity and Navier-Stokes equations) using the known package FLUENT in turbulent regime with appropriate turbulence model (κ-ε). Also measurement in experimental work will be carried out. The results indicate that the riblet surface models are the key parameters for controlling the boundary layer characteristics. The most effective riblet surface is U-riblet with fillet model (Mo.4, h = 0.1mm), by compare to smooth model, the results show a small increment in lift slope curve about 9% and total drag decrease 12% over the angles of attack range from (0° to 17°).
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7

Ninnemann, Todd, and Wing F. Ng. "Supersonic Through-Flow Fan Blade Cascade Studies: Part II — Riblet Effects." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0494.

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An experimental study to determine the effects of riblets on the performance of the Supersonic Throughflow Fan (STF) cascade blades was performed. The unique flow conditions of the STF provided a new application of using riblets to reduce aerodynamic losses. The cascade was tested in the Virginia Tech intermittent wind tunnel facility, where the Mach and Reynolds (based on chord) numbers were 2.36 and 4.8 × 106, respectively. The riblet sheets were symmetric v-grooved type and were applied onto the blade surfaces. Three different riblet heights were tested: 0.023, 0.033, and 0.051 mm. Riblet testing was conducted at design incidence as well as at off-design conditions (incidence angles: +5, −10 deg). To evaluate the performance of the riblets on the blades, a Pitot-static probe was used to measure the wake profile downstream of the cascade. The resultant total pressure profile was then integrated to obtain an overall mass-averaged loss coefficient. This loss coefficient was compared with a control test case where an equivalent thickness of smooth material is applied to the blade. Results show that at the design incidence, the riblet sheet with a height of 0.033 mm provides the optimal benefit, with a reduction of 8.5% in loss coefficient compared to the control case. Smaller effects were measured at the off-design conditions.
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8

aus der Wiesche, Stefan. "Heat Transfer and Drag Reduction in Flows Over Riblet Mounted Surfaces." In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47356.

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The heat transfer in a channel with its lower wall mounted with streamwise V-shaped riblets is investigated numerically using a LES approach. Both laminar and turbulent flows are considered. At the riblet wall the turbulent drag is reduced by 6% in comparison to the smooth wall, whereas for laminar flow the riblets lead to a significant drag increase. The effect of riblets on heat transfer is investigated explicitly for small Prandtl numbers Pr and an appropriate correlation is derived. This correlation indicates that the Reynolds analogy is not violated in case of Pr = 1 despite the extraordinary turbulent drag reducing mechanism. The numerical results for drag reduction are in good agreement with available experimental and numerical data, and the results are faced with corresponding heat transfer results found in the literature.
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Koepplin, Viktor, Florian Herbst, and Joerg R. Seume. "Correlation-Based Riblet Model for Turbomachinery Applications." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56293.

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An empirical riblet model for manufactured V-shaped and trapezoidal riblets which is suitable for turbomachinery application is presented. The implementation of the riblet effect employs a correlation-based correction for the damping of the specific dissipation rate omega in the vicinity of the wall which has been previously presented by other researchers. In the current paper the correlations are extended into the drag-increasing regime and are extended to account for the effect of misalignment of the riblets relative to the flow and for the effect of adverse pressure gradients. In order to account for the latter in modern, massive parallel CFD-codes, a local Clauser-Parameter has been newly derived. The model is implemented in the 3D turbomachinery design code TRACE and validated with flat plate measurement data and a NACA6510 compressor cascade. The predictions of the experimental values are in very good agreement with the experimental data, showing the capability of the model for designing riblet structured turbomachinery blading.
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10

Zenz, M., A. Hafizovic, L. Simonassi, P. Leitl, F. Heitmeir, and A. Marn. "Aeroacoustical and Aerodynamical Investigations of Riblets Applied on Low Pressure Turbine Exit Guide Vanes for Two Different Operating Points." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90283.

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Abstract One of the main goals for modern aircrafts is to lower the fuel consumption and noise emissions without worsening the aerodynamic performance. One possibility to lower the fuel consumption is to reduce the skin-friction losses of vanes and blades inside the engine. Therefore, this paper is about the aeroacoustical as well as the aerodynamical effects of a riblet foil applied on the suction side surface of turbine exit guide vanes (TEGVs) of a 1½ stage low pressure turbine (LPT). There have been numerous studies concerning riblets but none using them in a LPT. In general, if riblets are applied on the suction side of vanes or blades, they lower the drag and increase the lift. Test runs were performed under two different operating points in a subsonic test turbine facility for aerodynamic, aeroacoustic, and aeroelastic investigations (STTF-AAAI) located at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. One operating point was the design point of the riblets and the second one an off-design point. During the test campaign, two different set-ups have been investigated. One configuration with riblets applied on the suction side of the TEGVs, and one configuration with a smooth foil on the vanes to achieve the same thickness as the first set-up. This smooth configuration serves as a reference case. The tested riblet structure was of trapezoid type with 45 μm tip distance and a height to tip distance ratio of 0.45. The acoustical data has been obtained by using flush mounted condenser microphones, rotated over 360 deg around the flow channel. The aerodynamical data was obtained by using an aerodynamic five-hole-probe as well as a trailing edge probe. Measuring in planes up- and downstream of each TEGV allowed the comparison of a rough pressure loss estimation between the two studied set-ups. The present work gives a closer insight into the change of the acoustical and aerodynamical behaviour by applying riblets to LPT vanes.
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Reports on the topic "Riblets"

1

Dement, Franklin L. Effects of Pressure Gradients on Turbulent Boundary Layer Flow Over a Flat Plate with Riblets. Fort Belvoir, VA: Defense Technical Information Center, March 1999. http://dx.doi.org/10.21236/ada361555.

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