Validation of Tidal Stream Turbine Wake Predictions and Analysis of Wake Recovery Mechanism

Salunkhe, S.; Fajri, Oumnia El; O'Doherty, Timothy; Bhushan, Shanti; Thompson, David S.; O'Doherty, Daphne Maria; Mason-Jones, Allan

doi:10.3390/jmse7100362

Cited by 22 publications

(20 citation statements)

References 48 publications

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“…The reason is that the fine mesh resolution turns on the LES mode of the IDDES. 37 The gap turbulence is mixed with the main flow as it is swept downstream. This phenomenon was also observed previously.…”

Section: Results and Discussion A Inlet Gap Turbulencementioning

confidence: 99%

“…29 This setup was validated in the previous study, 30 where turbulence-induced acoustic waves transmitting through a cabin window were simulated. The turbulence is simulated using the IDDES 31 that is combined with the k-x shear stress transport (SST) turbulence model. This setup has been tested in several studies on rotating machinery.…”

Section: Numerical Methodology a Computational Fluid Dynamics (Cfd) Methodsmentioning

confidence: 99%

“…The coefficients of the IDDES model adopt the default values in the software STAR-CCM+, i.e., C DES;kÀx ¼ 0:78; C DES;kÀe ¼ 0:61; 31 The notation of the coefficients is the same as in the software user guide. 29 The wall-normal sizes of the first layer cells near all walls fulfill Dy þ < 1:…”

Section: Numerical Methodology a Computational Fluid Dynamics (Cfd) Methodsmentioning

confidence: 99%

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Tonal noise of voluteless centrifugal fan generated by turbulence stemming from upstream inlet gap

2021

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Volutes for radial-flow turbomachines (e.g., centrifugal fans and pumps) are spiral funnel-shaped casings that house rotors. Their function is to guide the flow from rotors to outlets and maintain constant flow speeds. Under specific conditions, however, volutes are removed (termed voluteless) to reduce flow losses and noise. In this paper, a generic voluteless centrifugal fan is investigated for the tonal noise generation at an off-design operation point. In contrast to typical tonal noise sources induced by the fan blades, we find out that another predominant source is the turbulence stemming from the clearance gap between the fan front shroud and the inlet duct. The turbulence evolves along with the front shroud and is swept downstream to interact with the top side of the blade leading edge. An obvious additional tone is observed at 273 Hz other than the blade passing frequency (BPF 0 ) and relevant harmonic frequencies. By coarsening the mesh resolution near the inlet gap and front shroud in the simulations, we artificially deactivate the gap turbulence. Consequently, the tone at 273 Hz disappears completely. The finding indicates that the interaction between the gap turbulence and blades accounts for the tone. As the gap turbulence exists near the front shroud, this rotating wall introduces rotational momentum into the turbulence due to skin friction. Hence, this tonal interaction frequency is smaller than BPF 0 with a decrement of the fan rotation frequency. To the authors' knowledge, this is the first time that voluteless centrifugal fans are studied for the gap-turbulence noise generation.

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Section: Results and Discussion A Inlet Gap Turbulencementioning

confidence: 99%

Section: Numerical Methodology a Computational Fluid Dynamics (Cfd) Methodsmentioning

confidence: 99%

Section: Numerical Methodology a Computational Fluid Dynamics (Cfd) Methodsmentioning

confidence: 99%

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Tonal noise of voluteless centrifugal fan generated by turbulence stemming from upstream inlet gap

2021

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“…The objective of this research is to validate the predictive capability of blade-resolved simulations for HKT thrust, power and intermediate wake predictions using flume data [2]. The study builds on the authors' previous blade-resolved HKT validation effort using Ansys/Fluent using RANS, Detached eddy simulation (DES) and LES models [22,29]. Their study demonstrated that, although blade-resolved simulations are sufficiently accurate for HKT thrust and power predictions, they exhibit deficiencies in the prediction of wake recovery.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of shallow-water effects on hydrokinetic turbine wake recovery

O'Doherty¹,

Thompson²,

Bhushan³

et al. 2020

Int. J. Mar. Ene.

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Thrust, power and intermediate wake predictions obtained using resolved rotating blade with sliding mesh simulations for a hydrokinetic turbine (HKT) are assessed using the open-source flow solver OpenFOAM. Single- and two-phase URANS and DES computations are performed for three-blade, 0.5m diameter (D) turbine mounted on a stanchion that intersects the free surface with a tip-speed ratio λ = 6.15. The thrust and power predictions compare within 5% of the experimental data. Results show that the thrust predictions are dominated by the pressure distribution on the blades, whereas the shear stress plays a significant role in the power predictions. The turbine performance showed unsteadiness with amplitudes around 3% of the mean, due to the disruption of the flow each time a blade passed in front of the stanchion. The wake recovery is primarily due to the growth of shear layers (originating from the blade tips) towards the turbine axis, which are primarily caused by the cross-plane turbulent velocity. The shear layer growth is enhanced by the turbulence produced by the stanchion. Predictions of the mean wake profile compared within 10% of the experimental data, which is significant improvement over previous Fluent predictions that showed large errors of 22%. The improved predictions in OpenFOAM is attributed to better turbulence predictions. Two-phase results show that the interaction between the wake and free-surface is initiated by the interaction of stanchion with the free-surface. The free-surface creates a blockage effect that accelerates the flow in the upper bypass region and enhances the wake recovery.

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“…Globally the interest in marine energy solutions is growing from Europe to Australasia to the Americas. This is reflected in the provenance of the authors of the following papers [1][2][3][4][5].…”

mentioning

confidence: 99%

The Development of Marine Energy Extraction

O'Doherty

Mason-Jones

2020

JMSE

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Validation of Tidal Stream Turbine Wake Predictions and Analysis of Wake Recovery Mechanism

Cited by 22 publications

References 48 publications

Tonal noise of voluteless centrifugal fan generated by turbulence stemming from upstream inlet gap

Tonal noise of voluteless centrifugal fan generated by turbulence stemming from upstream inlet gap

Numerical investigation of shallow-water effects on hydrokinetic turbine wake recovery

The Development of Marine Energy Extraction

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