Recent Advances in Numerical and Experimental Downwind Sail Aerodynamics

Souppez, Jean-Baptiste R. G.; Arredondo-Galeana, Abel; Viola, Ignazio Maria

doi:10.5957/jst.2019.4.1.45

Cited by 16 publications

(11 citation statements)

References 47 publications

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“…In some conditions, the advection of these vortices near the sail surface results, in a time-averaged sense, in flow reattachment and in a closed recirculation region near the leading edge known as a leading-edge separation bubble (LESB) (Smith, Pisetta, & Viola, 2021). This is a feature akin to those experienced by thin aerofoils (Arena & Mueller, 1977; Carter & Vatsa, 1982; Chang, 1970; Owen & Klanfer, 1953), flat plates at small incidence (Crompton & Barrett, 2000; Gault, 1957; Newman & Tse, 1992; Stevenson, Walsh, & Nolan, 2016) and circular arcs at low incidence above the ideal angle of attack (Cyr, 1992; Souppez, Arredondo-Galeana, & Viola, 2019).…”

Section: Introductionmentioning

confidence: 90%

“…This is a geometry which is similar to the mid-height section of the scale model spinnakers. The experimental data were provided by Souppez et al (2019) and measured in the towing tank of Solent University at Re = 150 000. The experiments were designed to measure the blockage effect on a finite-aspect-ratio circular arc at angles of attack of 15 • and 20 • .…”

Section: Declaration Of Interestsmentioning

confidence: 99%

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Vortex flow of downwind sails

Arredondo-Galeana

Babinsky²,

Viola³

2023

Flow

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This paper sets out to investigate the vortex flow of spinnaker yacht sails, which are low-aspect-ratio highly cambered wings used to sail downwind. We tested three model-scale sails with the same sections but different twists over a range of angles of attack in a water tunnel at a Reynolds number of 21 000. We measured the forces with a balance and the velocity field with particle image velocimetry. The sails experience massively separated three-dimensional flow and leading-edge vortices convect at half of the free-stream velocity in a turbulent shear layer. Despite the massive flow separation, the twist of the sail does not change the lift curve slope, in agreement with strip theory. As the angle of attack and the twist vary, flow reattachment might occur in the time-average sense, but this does not necessarily result in a higher lift to drag ratio as the vorticity field is marginally affected. Finally, we investigated the effect of secondary vorticity, vortex stretching and diffusion on the vorticity fluxes. Overall, these results provide new insights into the vortex flow and associated force generation mechanism of wings with massively separated flow.

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Section: Introductionmentioning

confidence: 90%

Section: Declaration Of Interestsmentioning

confidence: 99%

Vortex flow of downwind sails

Arredondo-Galeana

Babinsky²,

Viola³

2023

Flow

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“…Here, the term sails encapsulates soft sails, but also rigid wings, whether using airfoil [21] or the increasingly popular circular arcs section [22,23,24,25]. From a fluid dynamics point of view, a significant distinction needs to be made between sails where the flow remains attached, and those experiencing separated flow.…”

Section: Sailsmentioning

confidence: 99%

A Review of Wind-Assisted Ship Propulsion for Sustainable Commercial Shipping: Latest Developments and Future Stakes

Khan¹,

Macklin²,

Peck³

et al. 2021

WIN21

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With the current global warming crisis and contemporary concerns for sustainability, the transport industry is developing and implementing novel solutions to reduce greenhouse gases. With close to 90% of the world’s goods relying on maritime transportation, responsible for 3% of global energy-related carbon dioxide (CO2) emissions in 2019, there is a vital emphasis on reducing emissions. The latest legislation from the International Maritime Organisation has imposed even tougher sulphur oxide targets. On the other hand, emission intensity for CO2 will need to be decreased by 70% in 2050, compared to 2008 figures. While operating measures and fuel alternatives are suitable in the short-term to meet these novel regulatory constraints, as the use of fossil fuels tapers off, the long-terms solution appears to reside in wind-assisted ships. Consequently, this study aims to identify viable solutions that could reduce emissions, focussing on three prominent technologies, namely sails, rotors and kites. Furthermore, this review provides guidance on the benefits and risks associated with each technology and recommends guidelines for performance prediction and associated constraints. Ultimately, future stakes in wind-assisted propulsion are highlighted, including the need for full-scale validation, the challenge in assessing environmental and economic impact, and the structural issues associated with wind-assisted propulsion systems.

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“…In the last two decades, numerical and experimental advances in the aerodynamics of sails have contributed to a new understanding of their behavioural patterns and improved design [1].…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of the Aerodynamic Coefficients of a Sail Blade

Tleubergenova

Tanasheva

Shaimerdenova

et al. 2022

Preprint

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For more than a hundred years, wind turbines have been used to convert the potential of wind energy into electricity. In recent years, a trend has emerged in the form of a sharp increase in fossil fuel prices, as a result of which the development and production of wind turbines has greatly increased. The market for wind turbines is broad; however, in general, many of them are designed for relatively high wind speeds, typically from 10 to 15 m/s at low power. Central Asia is known for lower wind speeds, so the commercial wind turbines do not meet the energy demand. Against this background, the current topic is the development and research of wind turbines and their functional elements for low wind speeds, among whose representatives is the sail. The authors of the paper numerically studied the aerodynamic coefficients of the sail blade, determining the patterns of three-dimensional air flow around it and the pressure distribution field. The sail blade was modeled using the computer program ANSYS FLUENT based on the Reynolds-averaged (RANS) Navier-Stokes equations. The inflow velocity varied from 3 to 15 m/s. Comparative analyzes of the theoretical and experimental results are given. The patterns of changes in aerodynamic parameters determined by the authors could contribute to the understanding of the complex aerodynamic patterns of a turbulent flow around the blades.

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Recent Advances in Numerical and Experimental Downwind Sail Aerodynamics

Cited by 16 publications

References 47 publications

Vortex flow of downwind sails

Vortex flow of downwind sails

A Review of Wind-Assisted Ship Propulsion for Sustainable Commercial Shipping: Latest Developments and Future Stakes

Mathematical Modeling of the Aerodynamic Coefficients of a Sail Blade

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