Assessment of 2D/3D numerical modeling for deep dynamic stall experiments

Zanotti, Alex; Nilifard, Reza; Gibertini, G.; Guardone, Alberto; Quaranta, Giuseppe

doi:10.1016/j.jfluidstructs.2014.08.004

Cited by 34 publications

(17 citation statements)

References 23 publications

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“…Notice that the spanwise discretization of the grid is consistent with those employed in some other works for similar CFD simulations. In Zanotti et al., 36 a comparable spacing was used for the reference grid realized for three-dimensional dynamic stall computations, and refinement studies on the spanwise spatial resolution of the grid were also performed. These studies confirm that the spanwise spatial resolution of the grid here selected is appropriate for the present three-dimensional computations at low angles of attack on the lifting surface equipped with the L-tab.…”

Section: Geometry Of the L-tab And Numerical Modelmentioning

confidence: 99%

Numerical assessment of an L-shaped Gurney flap for load control

Motta

Zanotti

Gibertini

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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The aerodynamic performance of a novel trailing edge L-shaped flap design is characterized numerically by means of computational fluid dynamics. The device is primarily thought for aerodynamic load adaptation to flight conditions. The device could be applied on a broad range of flying vehicles, like rotorcraft, for which it has been primarily designed, and also fixed wing aircraft and wind turbines. The operation of this movable surface is twofold. On one side, when the device is deployed downward, it acts as a Gurney flap, allowing the increase of the aerodynamic lift, without severe drawbacks in terms of drag rise. On the other side, when it is deflected upward, it is found capable to significantly alleviate the negative effects of stall. Simulations are carried out on a NACA 0012 airfoil equipped with the present L-shaped device at several angles of attack, both in linear and stall regimes. The reliability of numerical computations is supported by comparisons with pressure measurements and PIV surveys. Moreover, for small angles of attack, a Mach sensitivity analysis is performed, to assess the effects of compressibility on the L-shaped flap. Additionally, this work highlights how such device, when designed appropriately, can even delay the static stall onset

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Section: Geometry Of the L-tab And Numerical Modelmentioning

confidence: 99%

Numerical assessment of an L-shaped Gurney flap for load control

Motta

Zanotti

Gibertini

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The numerical modeling of these flow conditions and its impacts on applications like turbomachinery is challenging. Even when simplified geometries such as pitching plates are used, obtaining accurate results requires costly three-dimensional simulations with high spatial and temporal resolution (Zanotti et al 2014). The loads on a VAWT can successfully be reproduced with numerical methods like large-or detached-eddy simulations, but underlying flow dynamics such as the onset of leading-edge vortices or the occurrence of the vortex shedding are not always reproducible with satisfying accuracy (Ferreira et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

et al. 2020

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The characteristics of the fluid-structure interaction on the flexible blades of a horizontal-axis water turbine are studied; this bioinspired technology features mechanical simplicity, performance and lifetime improvement, and low fish impact risk, all characteristics of a truly sustainable renewable energy exploitation. A surface-tracking method synchronized with force measurements was applied on a surrogate model of single-bladed, vertical-axis water turbine in a water channel. This allows for the characterization of the structural deformations and their link to the hydrodynamic forces, over a large range of turbine designs and operating points. It is shown that the phase angles of the maxima in blade deformation coincide with those of the load maxima on a rigid blade in identical flow conditions. The influence of the turbine's tip/speed ratio on the blade deformation and blade load is investigated. With the chosen blade design, hydrofoil deformation is found to be maximum in the operating points where the performance improvement is maximized (k o = 0.3). With lower values of reduced frequency (corresponding to lower rotation speed), fluid-induced forces dominate the fluid-structure interaction. Conversely, at higher frequencies, structural inertia dominates the interaction, and blade deformation is again reduced. Results suggest that the optimal blade rigidity may depend on the operating point; nevertheless the potential of the flexible-blade design is demonstrated through clear linking of fluid-induced forces and blade deformation in the complex flow conditions of the Darrieus water turbine.

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“…The three-dimensional effects are more frequently captured by numerical studies. Zanotti et al [14,15] conducted experimental and numerical investigations on a pitching NACA 23012 aerofoil and detected strong spanwise three-dimensional structures at the downstroke stage. They claimed that it was due to the intrinsic three-dimensional nature of dynamic stall.…”

Section: Introductionmentioning

confidence: 99%

Unsteady RANS Simulations of Strong and Weak 3D Stall Cells on a 2D Pitching Aerofoil

Liu

Nishino

2019

Fluids

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A series of three-dimensional unsteady Reynolds-averaged Navier–Stokes (RANS) simulations are conducted to investigate the formation of stall cells over a pitching NACA 0012 aerofoil. Periodic boundary conditions are applied to the spanwise ends of the computational domain. Several different pitching ranges and frequencies are adopted. The influence of the pitching range and frequency on the lift coefficient (CL) hysteresis loop and the development of leading-edge vortex (LEV) agrees with earlier studies in the literature. Depending on pitching range and frequency, the flow structures on the suction side of the aerofoil can be categorized into three types: (i) strong oscillatory stall cells resembling what are often observed on a static aerofoil; (ii) weak stall cells which are smaller in size and less oscillatory; and (iii) no stall cells at all (i.e., flow remains two-dimensional) or only very weak oval-shaped structures that have little impact on CL. A clear difference in CL during the flow reattachment stage is observed between the cases with strong stall cells and with weak stall cells. For the cases with strong stall cells, arch-shaped flow structures are observed above the aerofoil. They resemble the Π-shaped vortices often observed over a pitching finite aspect ratio wing.

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Assessment of 2D/3D numerical modeling for deep dynamic stall experiments

Cited by 34 publications

References 23 publications

Numerical assessment of an L-shaped Gurney flap for load control

Numerical assessment of an L-shaped Gurney flap for load control

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

Unsteady RANS Simulations of Strong and Weak 3D Stall Cells on a 2D Pitching Aerofoil

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