Reduction of turbulent skin-friction drag by passively rotating discs

Olivucci, Paolo; Wise, Daniel J.; Riccó, Pierre

doi:10.1017/jfm.2021.533

Cited by 7 publications

(1 citation statement)

References 36 publications

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“…The outcomes exhibit what polymer infusion means for the stage distinctions between serious wall-shear pressure occasions and the RSS that creates enormous scope lucid designs. [46] In a tempestuous channel stream, the movement of pivoting circles that are allowed to move and liable to wall disturbance is researched mathematically. The Navier-Stir-up conditions are associated nonlinearly to the dynamical condition of the plate movement, which combines the liquid stream limit conditions and is moved by force made by the wall-shear pressure.…”

Section: Drag Forcementioning

confidence: 99%

Study of the Moment of Drag and Lift on Different Air-foil Shapes and Thickness During Wind Tunnel Application: A Review

Ughapu,

Adaramola,

Oke

et al. 2023

E3S Web Conf.

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An experimental facility called a wind tunnel is used in aerodynamics to investigate how air behaves when it passes through solid things like wings or automobile bodies. Researchers can evaluate an object’s aerodynamic characteristics under many circumstances by producing a controlled airflow, including as variations in velocity, attack angle, or atmospheric pressure. The emergency of 3D computer simulation of the performance parameters of an airfoil which is characterised by optimisation and digital technology, are combined for easier determination of the aerodynamic characteristics of a chosen airfoil for better and effective lift and drag coefficient through computational simulations using software like ANSYS etc. The aim is to study the effect of lift and drag on different air-foil shapes and thicknesses at different angles of attack using experimental and wind tunnel applications for better validation. The study also reviewed work that cut across the effect of the different airfoil shapes and thickness in a wind tunnel experiment, drag force, lift force and numerical methods employed for wind tunnel experiment. This technological advancement is not without its difficulties and challenges, also discussed as possible solutions. The study further suggested integrating emerging technologies by using cutting-edge tools like machine learning and artificial intelligence to speed up the design and analysis of airfoil collaborations between academics and industry to ensure that airfoils foster design. Foster meets industrial standards and enables practical implementations.

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Section: Drag Forcementioning

confidence: 99%

Study of the Moment of Drag and Lift on Different Air-foil Shapes and Thickness During Wind Tunnel Application: A Review

Ughapu,

Adaramola,

Oke

et al. 2023

E3S Web Conf.

View full text Add to dashboard Cite

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Interactive experimental study on microgroove structure and drag‐reducing additives in rotating disk apparatus

Chang,

Huang,

Huang

et al. 2024

Asia-Pacific J Chem Eng

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A series of interactive experiments are conducted to analyze the drag reduction technology with a rotating disk apparatus that combines microgroove structure and drag‐reducing additives including polyethylene oxide (PEO), cetyltrimethyl ammonium chloride (CTAC), and sodium salicylate (NaSal). By varying the disk type, concentration of drag‐reducing additives, temperature, and Reynolds number (Re), the corresponding drag reduction rates are obtained effectively. The experimental results indicate that adding CTAC strengthens the heat degradation and shear resistance of PEO; while PEO can enhance the ability of CTAC to form micellar structures and balance energy distribution at low concentrations. Moreover, the synergistic effect of these two additives presents a better drag reduction performance with a maximum drag reduction rate of 24.1%; while the microgroove structure enhances the effect of active drag reduction. Therefore, the combination of active and passive drag reduction technology broadens the application of energy saving and consumption reduction in hydraulic rotating machinery.

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How do the finite-size particles modify the drag in Taylor–Couette turbulent flow

Wang

Jiang

et al. 2022

J. Fluid Mech.

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We experimentally investigate the drag modification by neutrally buoyant finite-size particles with various aspect ratios in a Taylor–Couette (TC) turbulent flow. The current Reynolds number, $Re$ , ranges from $6.5\times 10^3$ to $2.6\times 10^4$ , and the particle volume fraction, $\varPhi$ , is up to $10\,\%$ . Particles with three kinds of aspect ratio, $\lambda$ , are used: $\lambda =1/3$ (oblate), $\lambda =1$ (spherical) and $\lambda =3$ (prolate). Unlike the case of bubbly TC flow (van Gils et al., J. Fluid Mech., vol. 722, 2013, pp. 317–347; Verschoof et al., Phys. Rev. Lett., vol. 117, issue 10, 2016, p. 104502), we find that the suspended finite-size particles increase the drag of the TC system regardless of their aspect ratios. The overall drag of the system increases with increasing $Re$ , which is consistent with the literature. In addition, the normalized friction coefficient, $c_{f,\varPhi }/c_{f,\varPhi =0}$ , decreases with increasing $Re$ , the reason could be that in the current low volume fractions the turbulent stress becomes dominant at higher $Re$ . The particle distributions along the radial direction of the system are obtained by performing optical measurements at $\varPhi =0.5\,\%$ and $\varPhi = 2\,\%$ . As $Re$ increases, the particles distribute more evenly in the entire system, which results from both the greater turbulence intensity and the more pronounced finite-size effects of the particles at higher $Re$ . Moreover, it is found that the variation of the particle aspect ratios leads to different particle collective effects. The suspended spherical particles, which tend to cluster near the walls and form a particle layer, significantly affect the boundary layer and result in maximum drag modification. The minimal drag modification is found in the oblate case, where the particles preferentially cluster in the bulk region, and, thus, the particle layer is absent. Based on the optical measurement results, it can be concluded that, in the low volume fraction ranges ( $\varPhi =0.5\,\%$ and $\varPhi = 2\,\%$ here), the larger drag modification is connected to the near-wall particle clustering. The present findings suggest that the particle shape plays a significant role in drag modification, and the collective behaviours of rigid particles provide clues to understand the bubbly drag reduction.

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Reduction of turbulent skin-friction drag by passively rotating discs

Abstract: Abstract

Cited by 7 publications

References 36 publications

Study of the Moment of Drag and Lift on Different Air-foil Shapes and Thickness During Wind Tunnel Application: A Review

Study of the Moment of Drag and Lift on Different Air-foil Shapes and Thickness During Wind Tunnel Application: A Review

Interactive experimental study on microgroove structure and drag‐reducing additives in rotating disk apparatus

How do the finite-size particles modify the drag in Taylor–Couette turbulent flow

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