Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data

Abstract

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Analysis of Flow Timescales on a Periodically Pitching/Surging Airfoil

“…In the work of Simão Ferreira et al (e.g., [20]), in a rotating frame at Reynolds numbers near operating conditions and tip speed ratios of 2-4, observations of the growth of leading-and trailing-edge vorticities were made at a limited number of angular positions. The total vortex circulation was shown to grow until the vortex was shed at the point of dynamic stall, whereas computations found the maximum tangential force on the turbine blade to occur at θ ∼ 70 deg [20,21]. Experiments performed by Buchner et al [22] on single bladed turbines, at a tip speed ratios between 1 ≤ η ≤ 5 and dimensionless pitch rates K c c∕2R, found that, for a specific tip speed ratio, faster pitch rate resulted in less spatial growth of the LEV, resulting in weaker interaction between the leading-and trailing-edge vortices and delaying LEV separation.…”

Visualization by PIV of dynamic stall on a vertical axis wind turbine

“…The blockage effect of a VAWT is thus much smaller than what is calculated with the constant induction assumption used by Glauert (1935). To assess the extent of the blockage effect, a 2D Navier-Stokes numerical model is used (see Simão Ferreira et al 2007) to simulate the case of the rotor in the wind tunnel and compare with the simulation of the same VAWT in open field. The difference in thrust between the two cases is negligible; thus blockage effects are considered to be small.…”

“…3; the figure shows the nondimensioned tangential force and normal force over three rotations. The forces are simulated with an unsteady Reynolds averaged Navier-Stokes k-e improved model of the work presented by Simão Ferreira et al (2007).…”

3D CFD Analysis of a Vertical Axis Wind Turbine

“…However, Iida et al [21] used a model with large eddy simulations (LES), proving that the as-obtained results are in good agreement at high TSR with that of momentum theory, but the model was revealed to be not accurate for low TSR cases. Ferreira et al [22] use detached eddy simulation (DES) focusing on 2D dynamic stall and validate the results with particle image velocimetry data. It is to be noted that in the Darrieus-type VAWT, a cyclic phenomenon of dynamic stall and vortex separation is present [8,22,23].…”

“…Ferreira et al [22] use detached eddy simulation (DES) focusing on 2D dynamic stall and validate the results with particle image velocimetry data. It is to be noted that in the Darrieus-type VAWT, a cyclic phenomenon of dynamic stall and vortex separation is present [8,22,23]. Amet et al [23] provided a detailed numerical analysis of the physical phenomena that occur during dynamic stall where the compressible RANS κ − ω model and multi-block mesh structure were used.…”