Experimental validation of the power enhancement of a pair of vertical-axis wind turbines

Abstract

Wind tunnel tests have been performed of individual and paired H-type Darrieus vertical-axis wind turbines. The turbines in the paired configuration are closely spaced, at 1.2 and 1.3 rotor diameters shaft to shaft, and are counter-rotating. Two directions of rotation were studied, one where the facing (inner) blades move along with the incoming flow, and one where the facing blades move against the wind. The wind tunnel tests confirm a net increase in the power coefficient of the paired configuration compared with twice the power coefficient of the individual turbine. We found average relative increases in the power coefficients between 13 % and 16 %, which is consistent with numerical studies available in the literature.

Experimental characterisation of the wake behind paired vertical-axis wind turbines

“…Pairing VAWTs exhibits advantages with regards to the performance (e.g. (Vergaerde et al, 2020)) and can potentially be used for applications in wind farms. For floating offshore applications, the benefits of paired VAWTs can be complemented with benefits for the floating platforms.…”

“…The platforms for such floating applications greatly impact the cost of offshore energy and, while being less efficient than HAWTs, VAWTs could be economically more viable (Tjiu et al, 2015;Paulsen et al, 2013;Hand and Cashman, 2020;Bull et al, 2014). Furthermore, placing counter-rotating VAWTs side by side in close proximity allows them to benefit from an increased power making such configurations promising for wind farm applications (Dabiri, 2011;Duraisamy and Lakshminarayan, 2014;Kinzel et al, 2012;Zanforlin and Nishino, 2016;Vergaerde et al, 2020). This benefit has inspired innovative concepts such as the placement of two counter-rotating VAWTs on a same floating platform (Parneix et al, 2016).…”

Impact of urban environment on Savonius wind turbine performance: A numerical perspective

“…Literature about Savonius VAWT studies includes both wind tunnel tests and numerical simulations. Typically, the first ones are mostly focused on the optimization of the blade shape [24] and consist in wind tunnel test measurements [25] at different tip-speed ratio (TSR), overlap ratios and aspect ratios or even multiple stage designs [26,27]). In this regard, CFD studies can be mainly classified considering 2D and 3D inspection methods.…”

A Double Multiple Stream Tube (DMST) routine for site assessment to select efficient turbine aspect ratios and solidities in real marine environments

“…When using a sliding mesh, to obtain a satisfactory numeric convergence the time-step should not be larger than the time required for advance the mobile interface by a distance corresponding to one cell thus, in order to consider the smallest cell at the interface, a time-step corresponding to 0.5° of revolution was adopted. The overall validation of the 2D CFD model has been described in a previous article [22] in comparison to the experimental data by Bravo et al [23], whereas the validation of the 3D CFD model has been done versus the wind-tunnel velocity profiles achieved by Vergaerde et al [24] at several locations downstream a two straight bladed turbine (details of the validation in [25]).…”