English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. The periodic, helical vortex wakes of wind turbines, propellers, andhelicopters are often approximated using straight vortex segments whichcannot reproduce the binormal velocity associated with the local curvature.This leads to the need for the first curvature correction, which is well knownand understood. It is less well known that under some circumstances, thebinormal velocity determined from straight segments needs a second correctionwhen the periodicity returns the vortex to the proximity of the point atwhich the velocity is required. This paper analyzes the second correction bymodelling the helical far wake of a wind turbine as an infinite row ofequispaced vortex rings of constant radius and circulation. The ring spacingis proportional to the helix pitch. The second correction is required atsmall vortex pitch, which is typical of the operating conditions oflarge modern turbines. Then the velocity induced by the periodic wake can greatlyexceed the local curvature contribution. The second correction is quadraticin the inverse of the number of segments per ring and linear in the inversespacing. An approximate expression is developed for the second correction andshown to reduce the errors by an order of magnitude.

The second curvature correction for the straight segment approximation of periodic vortex wakes