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Geometrical characterization of stall cells on rectangular wings

Marinos Manolesos, Spyros G. Voutsinas

Wind Energy, Pages: n/a - n/a

Swansea University Author: Marinos Manolesos

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DOI (Published version): 10.1002/we.1634

Abstract

The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% thick airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been...

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Published in: Wind Energy
ISSN: 1095-4244
Published: Wiley 2014
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URI: https://cronfa.swan.ac.uk/Record/cronfa38905
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2019-09-16T12:24:24.7153698</datestamp><bib-version>v2</bib-version><id>38905</id><entry>2018-02-28</entry><title>Geometrical characterization of stall cells on rectangular wings</title><swanseaauthors><author><sid>44a3e0d351ccd7a8365d5fc7c50c8778</sid><firstname>Marinos</firstname><surname>Manolesos</surname><name>Marinos Manolesos</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2018-02-28</date><deptcode>FGSEN</deptcode><abstract>The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% thick airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been known for long, neither are their characteristics completely documented nor their generating mechanisms fully understood. The present investigation aims at providing additional information on the geometric characteristics in terms of width, length and occupied area. The relevant data are presented as functions of Reynolds (Re) number, angle of attack and aspect ratio (AR) of the model. In the tests reported, the dynamic character of SCs is suppressed by imposing a localized flow disturbance. For the specific airfoil and for the Re and AR range tested, it is found that: the angle of attack at which SCs are initially formed decreases linearly with Re number and independently of the AR; unlike two&#x2010;dimensional separation, their chordwise length increases with Re; the SC area relative to the wing planform area (defined as the relative SC area) grows asymptotically with angle of attack and Re number reaching an upper bound, which is independent of the AR; at intermediate angles of attack, the SC relative area is higher for the lower AR wing; for a fixed increment in Re number, the growth of the SC relative area is independent of the initial Re number; at lower angles of attack, the actual SC area is independent of the wing span.</abstract><type>Journal Article</type><journal>Wind Energy</journal><paginationStart>n/a</paginationStart><paginationEnd>n/a</paginationEnd><publisher>Wiley</publisher><issnPrint>1095-4244</issnPrint><keywords/><publishedDay>7</publishedDay><publishedMonth>8</publishedMonth><publishedYear>2014</publishedYear><publishedDate>2014-08-07</publishedDate><doi>10.1002/we.1634</doi><url>http://dx.doi.org/10.1002/we.1634</url><notes>This paper is the first of the outcomes from the GZF032 / 2009&#x2013;2010 Onassis PhD scholarship grant. It sets the ground for Stall Cell research and based on its findings a number of publications followed (including https://doi.org/10.1063/1.4869726, https://doi.org/10.1016/j.jweia.2015.03.020, https://doi.org/10.1002/we.1609). The main finding, which was not known at the time, is that it is possible to stabilize the inherently unsteady Stall Cells, which are 3D coherent structures of separated flow. The work is relevant to different types of separated flows from Unmanned Air Vehicles to Wind Turbine blades, as Stall Cell instability is linked to flutter and aeroelastic loads.</notes><college>COLLEGE NANME</college><department>Science and Engineering - Faculty</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>FGSEN</DepartmentCode><institution>Swansea University</institution><apcterm/><lastEdited>2019-09-16T12:24:24.7153698</lastEdited><Created>2018-02-28T18:10:37.4607587</Created><authors><author><firstname>Marinos</firstname><surname>Manolesos</surname><order>1</order></author><author><firstname>Spyros G.</firstname><surname>Voutsinas</surname><order>2</order></author></authors><documents><document><filename>38905__8781__6fd215d3bd8a44a2bc337c3a61e376a7.pdf</filename><originalFilename>manolesos2014(2).pdf</originalFilename><uploaded>2018-04-30T09:51:57.9630000</uploaded><type>Output</type><contentLength>1916758</contentLength><contentType>application/pdf</contentType><version>Accepted Manuscript</version><cronfaStatus>true</cronfaStatus><embargoDate>2018-04-30T00:00:00.0000000</embargoDate><copyrightCorrect>false</copyrightCorrect><language>eng</language></document></documents><OutputDurs/></rfc1807>
spelling 2019-09-16T12:24:24.7153698 v2 38905 2018-02-28 Geometrical characterization of stall cells on rectangular wings 44a3e0d351ccd7a8365d5fc7c50c8778 Marinos Manolesos Marinos Manolesos true false 2018-02-28 FGSEN The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% thick airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been known for long, neither are their characteristics completely documented nor their generating mechanisms fully understood. The present investigation aims at providing additional information on the geometric characteristics in terms of width, length and occupied area. The relevant data are presented as functions of Reynolds (Re) number, angle of attack and aspect ratio (AR) of the model. In the tests reported, the dynamic character of SCs is suppressed by imposing a localized flow disturbance. For the specific airfoil and for the Re and AR range tested, it is found that: the angle of attack at which SCs are initially formed decreases linearly with Re number and independently of the AR; unlike two‐dimensional separation, their chordwise length increases with Re; the SC area relative to the wing planform area (defined as the relative SC area) grows asymptotically with angle of attack and Re number reaching an upper bound, which is independent of the AR; at intermediate angles of attack, the SC relative area is higher for the lower AR wing; for a fixed increment in Re number, the growth of the SC relative area is independent of the initial Re number; at lower angles of attack, the actual SC area is independent of the wing span. Journal Article Wind Energy n/a n/a Wiley 1095-4244 7 8 2014 2014-08-07 10.1002/we.1634 http://dx.doi.org/10.1002/we.1634 This paper is the first of the outcomes from the GZF032 / 2009–2010 Onassis PhD scholarship grant. It sets the ground for Stall Cell research and based on its findings a number of publications followed (including https://doi.org/10.1063/1.4869726, https://doi.org/10.1016/j.jweia.2015.03.020, https://doi.org/10.1002/we.1609). The main finding, which was not known at the time, is that it is possible to stabilize the inherently unsteady Stall Cells, which are 3D coherent structures of separated flow. The work is relevant to different types of separated flows from Unmanned Air Vehicles to Wind Turbine blades, as Stall Cell instability is linked to flutter and aeroelastic loads. COLLEGE NANME Science and Engineering - Faculty COLLEGE CODE FGSEN Swansea University 2019-09-16T12:24:24.7153698 2018-02-28T18:10:37.4607587 Marinos Manolesos 1 Spyros G. Voutsinas 2 38905__8781__6fd215d3bd8a44a2bc337c3a61e376a7.pdf manolesos2014(2).pdf 2018-04-30T09:51:57.9630000 Output 1916758 application/pdf Accepted Manuscript true 2018-04-30T00:00:00.0000000 false eng
title Geometrical characterization of stall cells on rectangular wings
spellingShingle Geometrical characterization of stall cells on rectangular wings
Marinos Manolesos
title_short Geometrical characterization of stall cells on rectangular wings
title_full Geometrical characterization of stall cells on rectangular wings
title_fullStr Geometrical characterization of stall cells on rectangular wings
title_full_unstemmed Geometrical characterization of stall cells on rectangular wings
title_sort Geometrical characterization of stall cells on rectangular wings
author_id_str_mv 44a3e0d351ccd7a8365d5fc7c50c8778
author_id_fullname_str_mv 44a3e0d351ccd7a8365d5fc7c50c8778_***_Marinos Manolesos
author Marinos Manolesos
author2 Marinos Manolesos
Spyros G. Voutsinas
format Journal article
container_title Wind Energy
container_start_page n/a
publishDate 2014
institution Swansea University
issn 1095-4244
doi_str_mv 10.1002/we.1634
publisher Wiley
url http://dx.doi.org/10.1002/we.1634
document_store_str 1
active_str 0
description The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% thick airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been known for long, neither are their characteristics completely documented nor their generating mechanisms fully understood. The present investigation aims at providing additional information on the geometric characteristics in terms of width, length and occupied area. The relevant data are presented as functions of Reynolds (Re) number, angle of attack and aspect ratio (AR) of the model. In the tests reported, the dynamic character of SCs is suppressed by imposing a localized flow disturbance. For the specific airfoil and for the Re and AR range tested, it is found that: the angle of attack at which SCs are initially formed decreases linearly with Re number and independently of the AR; unlike two‐dimensional separation, their chordwise length increases with Re; the SC area relative to the wing planform area (defined as the relative SC area) grows asymptotically with angle of attack and Re number reaching an upper bound, which is independent of the AR; at intermediate angles of attack, the SC relative area is higher for the lower AR wing; for a fixed increment in Re number, the growth of the SC relative area is independent of the initial Re number; at lower angles of attack, the actual SC area is independent of the wing span.
published_date 2014-08-07T03:49:21Z
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score 11.014067

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