Waka, Ryoji

Yoshino, Fumio

Tottori University Research Result Repository

The Spanwise〕Distributions Of characterist―icValues near a Side―Wa1l of a CircularCylindeF with Tangential BIOwing(Effect Of Angular Location Of a B10wing S‐lot)byRyoji wAKA*and FttmiO YO鋭■No*l pepartnent of Mechanical EngineeFing(Recdved August L 1994)The e卜peament was caried Out t。●nderstand the efttct of tlte anguИr 10catiOn ofabユowing slot on tne spanwitt di飢五butiOns Of variOぃch acteFistic values near theside,wa1 0f a drc,lar cylillder wi“tanttt a  blo ng. The ristributions of thecharacteFiStiC values near the ude―wall are muth influenced,alld the Fantt Of the side―wall―effects is alteredメbア▼a ylng tho 10catiOn of the―dot.  Wla n―he shape Of theslot,kea k■ife edge is薗,the ttnge Of the si礎.waII「e郎∝t "eCOmes naすower asthe anguraF iOcation OF the biowing sIOt is moFe dOWnstrea4112    Ryoii VAKA and Fumio YOSHINO:The Spanwise Distributions of Characteristic Valuesnear a Side‐waH of a Circular Cj/1inder with Tangential Blowing    (Effect of AngularLocation of a Blowing S10t)■. Introductionup to dater the authors have carried out the synthetic investigations on acircu■ar cy■inder with tangentia■ blowing inc■uding  the  visualization of thef■ow itse■f inside the test section and those on varェous characteristic va■ue(1)～(3)such as aerodynamic coefficients.According to these, a ro■■ up of a strong vortex took p■ace near the side―wa■ in a case of a circular cy■inder even if the experiment was carried out ona two―dimentiona■ mode■. Hencer there ■s a wェd range near the side―wa■ inwhich the approx■mation of the two―dimens■onal flow no ■onger ho■dsP and theeffect of induced velocity is not neg■igible even at the mid―span where thetwo―dimensiona■ approximation is app■icable.  This is an important prob■em fa circular cylinder in particu■ar′ s ce it is difficu■t to make an aspect ratioof the cy■inder with b■owing ■arge enough.Now′ the range of the s■de―wa■■―effects is defined as the sem■―sp n minuthe spanwise distance from the mid―span to point from which toward the sェde―wal■ the two―dimensional approximation is not app■icab■e.  Then it is importantto understand not only the spanwise distribution of induced ang■of attack butalso the range of the s■de―wa11-effects. However′≒4デI身8Pre On・y few investiga―tions on the circular cy■inder with tangential b■owi g nd even fewer investiga―tions on the f■ow near the side―wa■ o far.  This may have been caused by com―p■exity of this prob■em and experimenta■ d fficuty due to numerous parameters.From the viewpoints mentioned above, the authors already pub■ished a paperon the range of the side―wal■―effects and the s弓子PWiSe diStribution of inducedang■e of attack ca■cu■ated theoretica■■y and so on.  After that, the experiment twith the angu■ar location of the blowing s■ot as a parameter was carr■d out′since the investifation on the side―wa■―effec s was yet insufficient.In this report′ the effects of the slot ■ocation n various characteristicva■ues near the side―wa■ are discussed on the basis of known facts in the pre―vious repOrtS.2, NomencとatureCd   : section drag coeffic■entC.   : section lift coeffic■entCln    lift C°e fic■ent norma■izedCp     pressure coeffic■entCpb  : base pressure coeffidientC‖     !:彗三争'i1/:;;::】::ent °f theby C. at the mid―spanblowing ぅet [=(mOmentum of うet per unit????: diameter of the cェrcu■ar cy■inder: Reyno■ds number (=U∞D/り)Reports Of the Faculty of Engineering, TOttOri Universityj V01. 15: ve■ocity of a un■fOrm f■ow: coordinate taken tO the port directiOn frOm the starboard side―wa■: = yw/D ( ηw=-4 at the mid…span): ang■e measured c■Ockwise frOm the leading esge of the cy■inder: angu■ar Ocation of the s■O: angular positiOn of the separation point on the upper surface of thecy■inderり    : kinematic v■scOSity Of a■rp    : dencity of airSubscriptO    : va■ue at the mid―span3。 Experimenta■ Apparatus and Method3-■ Experimenta■ apparatus(1)The experimenta■ apparatus used fOr the present investigation is the sameone as a■ready described except fOr a height Of the s■ot.Figure l shOws a cross sectiOn of the mode■ cy■inder.  A ho■■ow cy■inderwith an Outer diameter of ■oo mm and a sma■■ cylinder with a diameter of 25 mmform a b■Owing sとOt with a constant height Of o.58 mm acrOss the whoコ_e span.The outer surface Of the cy■inder is hrOm■um―p■ated and the static pressure holes Of 335 intotal are cェcumferentia■■y distributed at tenspanwise sections.Figure 2 shOws a test section of the windtunne■.  The modeと,cy■inder is mounted at thecenter of the test section and passes through twOpartition―plates of ■o mm thick inside the testsection (hereinafter referred to as Wside―wa■‖)and the tunne■ wa■s.The shape Of the s■ot Of the cy■inder―side―   Fig.wall juncture used in this experiment is i■■us―随rtition―plote??????????U。■ Cross section of themode■ cy■inder1000Fig.2 Test sectiOn of the wind tunne■Fig。3 Shape of the s■otRyoji VAKA and Fumio YOSHINO i The Spanwise Dist?butiolrts of Charact ristic Valuesnear a Side‐waH of a Circular Cylinder with Tangential Blowing     (Effect of AngularLocation of a Blowing Siot)trated in the dotted circ■es in Fig。3.  It is ca■■ed ‖Edge TypeW here and abbre―viated as ‖EDW.3-2 Experimenta■ thodThe experiment was carried out by varying Oj and c‖ under the conditions ofconstant Re of 2.■X■05, constant aspect ratio of 8 and a fixed shape of the slotofo D sh?wn in Fi?。 3. Oj was varied to five different■cations o  Oj  50  , 70 ,90 ′ l■O  and 120 .The experiment for each Oぅ is diVided into two parts one of which is  acase of varying cv arbitrari■y, the other of which is a case of adjusting CII soas to give the same value of C.O at each Oj.  Two desired va■ues of C.  were usedaiming at about 3。6 and 6.2. The circumferentia■ static pressure  distributionswere measured with a multitube manometer for a■l he cases mentioned above.4. Experimenta■ R su■sFigures 4(a)and (b)show the spanwise distributions of Ou.  In the figuresfrom Fig. 4 to 6, (a) indicates the case of varying cll arbitrari■y for ach Oぅand (b)the case of adjusting cll so as to give the same va■ue of C.O at each Oぅ。According to Fig. 4(a),  Ou gradually increases  with an approach to theside―wal■ and after taking a maximum va■ue′ Ou rapid■y ecreases.  When eぅ isfixed and CII  ncreases, Ou  ncreases over the who■e span with th  increase of Cμand in genera■ the larger eぅ is′ the larger Ou  S・ Since Ou  as a minimum valueat the side―wa■ ( ηw=0 ), it is found that the separation of f■ow first occuresthere.  The spanwise position of the max■mum point scarcely moves by the changeof Cv but moves toward the side―wall as O. ncreases.コIn the case of the same va■uc of C.0 (Fig. 4(b)), the spanwise distributionis considerab■y different near the side―wa■ among Oj:s used here a■though thevalues of c10 are near■y constant irrespective of the va■ues of Oj.  Name■y′ inspite of sma■■ c‖′ the ■arger Oj isr the larger the maximum value of Ou iS・Moreover, as Oj increases, the spanwise position of the maximum point moves to―ward the side―wa■l.Figures 5(a) and (b)show the spanwise distributions of Cpbo  Now, Cpb iSdefined as a mean valuc of C Is at the upper and ■ower separation points. InpFig. 5(a), Cpb gradually decreases with an approach to the side―wa■l and ftertaking a minimum va■ue near the s■de―wa■, cpb rapid■y ncreases.  Onc he otherhandP cpbO increases with the increase of c‖  or a■1 0ぅ s°  When Ojこ70 ,the min―imum point is not c■early seen near the side―wall even when Cw is re■atively■aFgeand  Cpb mere■y decreases a ■itt■e toward the s■de―wa■.  The difference in thespanwise distributions of cpb among different Cvis is also ■ittle.  Wh  Oj=90′if CII s iarge enough′ th  minimum point of cpb iS C・early seen.  As Cll  ncreasei′both Cpb:S near the side―wa■l and at the minimum point decrease.  When Oj≧1■0 ,the minimum point of Cpb appears near the side―wall eve  when Cv s small enough′Reports Of the Faculty Of Engineering, TOttOri University, V01 150-053::uとna::こ:i:子・:i。き!in ixei:こ: i::: ::きことこ。ri■こと二とutti二:mi4°と:ilと・is ::aどi;i」|!こ三::!::をt。:fOi! ′ depends On oぅ 。n■y' and it moves tOward the side―wal■with theコOf C.i:3::gin:(:!ちlhttI:lu::0:ξれbO席!;i::::::i:::::::‡:・i「。li::::aiii:i::i::ξを::二呈Ssidpと_二ξ:こu]‐・とh:e::::S:: :.:i:ii:ie ュニ!mum :::n:・! 6と〔a::」eき誕l iことr:::::::iξ::::i:::|:::i。:::r:::::きi・を:i::|remar:こ:;:eをn6i!; :二:e(:手 :i:iOth:°とこ: iCd gradua■■y increases with an approach tO the side―wa■ and after taking a max―:とuとd ilとこどζと二阜;:ii子::C:二S::re_与:.iμ:ど:::::::′」1)せlどJtOitどaltti m::imととn音:1と:Ol  cぃ ????????????????????‐???????????????????????，????????―‐??????」???。??????????????50  Δ 027△ 03570'.0018tt 0250 03615015001501501000(b)Fig。4 Spanwise distributiOns Of oq。キ62Re=2卜l oS?ぃ? ? ?? ‐ ?? ? ?? ‐ ?? ? ??，????ド子◇∫♭◇016120・、▽005▽01(‖∫.◇ 087001100160025120・,▽ 005▽ 014〜???C10、36Re=2卜105Fig.5 Spanwise distributions Of cpb16   Ryoji WAKA and Fumio YOSHINO:The Spanwise Distributions of Characteristic Valuesnear a Side‐wall of a Circular Cylinder with Tangential B10wingLOcation of a BIowing SIOt)(Effect of Angularincrease a litt■e w h the increase of CII  nd there are max■mum va■ues in thespanwise distributions of each oj which increase with c .  The distribution‖curve  becomes sharper near the max■mum poェnt and this tendency becomes strOngwhen CIl increases beyond the va■ue of about O。■. Moreover,the spanw■s positionof the max■mum point is independent of c‖ nd moves toward the sェde―wa■ withthe increase of O..コIn Fig. 6(b)′when c10≒3.6, the spanwise distribution c!rve of Cd iS re■a―tively smooth without a c■ear peak for each Oぅ.  when oj≧l■   the distributioncurve near the side―wall is sharper compared with that of !ぅ≦70 , ano the dis―tribution curve of Oj 90  ■ies in between those of Oj≧■■O  and  oj≦70  .  Thistendency described here is more emphasized in the case of C.0≒6.2. When C10≒6.2,the distribution curve near the peak becomes particuraly steep in the case ofeぅ室l■0 ・  For ej=9o , cd becomes ■arger over the wide range of the span.  Thespanwise positions of the maximum point of cd moves toward the side―wal■ withthe increase of O, for a■■ the cases of C.0.  M°reover′ the value of Cd is ■ess]than that of cdO very near the s■de―wa■。  Howev r, any systematic dependence°n Oう iS nOt Observed in cdO。Now, the spanwェse distance from the s■de―wa■l to the point of the extremumfor each characteristic va■ue, ηw′ is tabuted in Table I′ wh n Oぅ is varied.Figure 7 shows the spanwise distributions of cin・ The exper mental results莉  Cμ50・,△ 027△03510S05050Tab■e I Spanwise positions of theextremum of characteristicva■ues靱-0,98-0.92-0.65-0.50l_4UCpb‐0.52-0,46-0.28-0.22-0,18-0,88中0.80-0.60-0.38-0.34Vo「tex‐0.61‐0.52‐0.40-0。25‐0.22S?．??■wFig.7 Spanwise distributions】???? 0of C n????????????????????0デ Cμl10,◇007◇016◇025120,▽005∇014Re=2.1■05Fig.6 Spanwise distributions of cdReports Of the Faculty Of Engineering, TOttOri University, Vol. 158」・70°CII=036::t:::y とiya:とe:i:写二°in tiこ:t:こgiュe:° こ:V:とiqこ:・こと9e と:。こ:二; :|: :こ: :i:iti::::ri∴とniS. :::とこylttSiSslことe:s と。:id と二:pendently of cII  ■thin the range of ex―:ことfr慧:::与:::ii::i:|をi阜 :二::::u:::liti温追nま::itii:と:i?nai:r:!:≒!:::at C.0≒6.2.  This figure is a deve■oped「e c■earer image of the separated regiOnnear the sュd ―wa■.  There is a particularly ユ。w pressure part in the separatedregiOn near the sェde―wa■i.  According tO the observatiOn of the ■im■ting stream■ines On the cy■inder surfacer the spanwise posェtiOn of this lower pressure partis in accOrd with that of a vOrtex shed direct■y frOm the cy■inder surface andswal10wed up into the center of the trai■ing vortex. As Oj increases, the vortexmoves tOward the sェe―wa■ and the pressure gradient near the vortex becOmessteeper.  Hence′the two―dimens■Ona■ regiOn becOmes wider in the ■eft sェde ofthe vortex by the rightward movement of that with the increase of O..]lllllll o～:I刷国 刊7P司側剛 125争I側□ ■7:L彪勿-050-07rDttN l oo～司26睡爾引50～」75Cp・:iRe=21x10S8j・ 120°Cμ・ 014E0「墨:SepolctiOntine1翌hY■‐052Fig.8 Static pressure distributions On the cylinder surface5, DiscussiOn5-l The range of the s■de―wa■―effectsThe spanwise range Of the side―wa■l―e fects was defined as the range nearthe side―wa■ in which the fとow around the cylinder was no ■Onger approxュmatedas quasi―twO―dimensiona■.  Then′ it is expected that the range of the side―wa■―effects is c■Ose■y related to the spanwise position of the ro■led―up―shed vortexnear the side―wal■,  since the positiOn Of the vortex moves toward the side―wa■↑h=l1220」・90°Cぃ・026CI・:iノ~Sepo「otiontineRyoJi lVAKA and Fumio YOSHINO:The Spanwise Distributions of Characteristic Valuesnear a Side‐wall of a Circular Cylinder with Tangential BIowing     (Effect of AngularLOcation of a BIOwing SiOt)with the increase of Oj as shown in Tab■e I′the rangeof the s■de―wal■―effects wi■■ become narrower with theincrease of oぅ.  The method determining this range wasalready described in references of (■) and (3).  Theranges of the side―wa■―effects obtained by this methodfor various oj:s are tub■ated in Tab■e II. As mentionedabover thiS range ■s a■so altered according to the var―■ation of the spanwise position of the vortex and it be―comes narrower with the increase of Oj.  Then, the s■otought to be located as downstream as possible in orderto obtain the two―dimensional range in the experimentas w■de as poss■b■e.5-2 The re■ation between the sとot position and the rangefectsAs mentioned in the preceding section,■s closely related to the spanwise posェtionFigure 9 shows the re■ation between ηwnearly proportiona■ to Oぅ, and Since thisTab■ II Range Of theside―wal■―effectsof side―wal■―efthe range of the side―wa■―effectsof the vortexrnwvand eぅ 。btained from Tab■e I.  ηwvrelation is independent of Cμ′ ηw8J5e△,0 090 oPe=21x105‖00120▽should be determined by Oぅ on■y・Next, the relation between (c10-C.w)and (CpbO~Cpbv)・/2 is shown in Fig.10,  Now′ cpbv iS the minimum value in the spanwise distribution of cpb and iS:;r::c:igai二id P: こiea;::;をilttlecia:teと二: :呈:eita:te(帝i二iFi C°|=p:i」をとをSyと'ぢd::propOrtional to (C.0-C■w)・ Since (C.0-C■w)iS proportiOna■ to the tota■ amountof the tra■■ing vortex shed from the cy■inder between the mェd―span and the side―Wa■(hereinafter referred to as Wstrength of the trai■ing vortex‖),(CpbO~Cpbv)・/2Re=2Jx1050   50    70    90    110120げFig。9 Re■ation between ηw and Oj儀―CwFig.■0 :三をaiを::0:::と急;1/ぢC・0~C・w)????）〓?―a5町1.451.30-1.24―+20Reports Of the Facuity of Engineering,TOttOri Universittt v01 156。 Conc■usiOnsExperiment was carried out On thespanwise distributions Of various char―acteristic va■ues of the circular cy■inder with tangentia■ b■Owi g fOr variots■ocations Of the siot and ぅ t intensities.  The conc■usiOns from a■■ Of theseare as f。■10ws,(■)The range Of the side―wa■―effects is obtained for each ■Ocation of thes■ot as shOwn in Tab■e II.(2)The range Of the side―wa■l_effects becomes narrower  with  the increase(3):: :: ::dfi三et issld::ξni s:IIttistributiOn of c. is simi■ar except fOr(4)::: :こ:n:!it。:‖ i: ことことをxa::r:jこ・iropOrtiOna■ tO that of the traifingvortex.References(■)Yoshino′ F.′ et al.′ Bulletin of the 」sMEァvo■。24, No.■92 (■98■-6)′ p.926.(2)wakar R.′ et a■。′ Int. sympO. 。n Flow visua■ization, Bochum (■980), p.528.(3)waka′ R.′ et al.′ Bul■etin Of the 」sME′ vol.26′ No.2■5 (■983-5)′ p.755。(4)Dunham′ 」.′ J.F■uid Mech.′ v。1.33′ part 3 (■968-9), p.495.ought tO be proportiona■ tO the strength Of the trailing vOrtex.tiona:nt:h:h:t!::e:3と二′。とCこ賀g i Pととi/:::e i鬼乙て哲r:;bと,′ 1亀e鷲 ことm:|三:とaとを:p:::square root Of pressure difference between the pressure of vOrtex cOre  nd thatin the separated regiOn distant enough from the vOrtex cOre. TherefOrer if Only:ュdと:i:こiS三:eどと言をilt:°::::二tttCと:n:と晋|と′ ::nと:rtiき ::ξ二w:!:ui:sとことn :とai:rt:と;!:と!:i!iこ::::::::::どとi;n:iξ二::|!::d::::::‡yき :と:!::ii:|!::こ:I:(1:|::ii:C:i;と::r写::::x ::こと とittことn:ial;g:Otigbご!!!乏It is cOnc■uded frOm  these  discuss■Ons that the  spanwise positiOn  and  thestrength Of the vortex cOre are a■tered on■y by Oj and (C.0-C■w)respectively′keeping its size cOnstanto  cOnsidering ■ike this′  ■t is ξOund that the larger::C:争;i。「F::「 :i::子uleきiiと: ::。iptxe t the Case of oj≧90 than that in the casencreas in the strength Of the  vortex:こ:三 :とec:ist:写ti::iiaSe of (c.0_Cとw)when On■y Oj is varied  under the cOndi―20   Ryoii VAKA alld FumおYOSHINO:The Spaltwise Dist?bu iOn  OF Characteristic Valu縄near a side wall of a CiFCular Cylinder with Tangential Blowing    (Effect of AngulaFLOca―tion of a BIOwing Slot)(5)Sato, M. and Matsuoka, K., Tran,. 」apan Soc, Moch, EngrSo (in Japanes.e),vol.36= ―No.2.89 (■70‐9), っ。1493.(6)FuFuya, V, and VoShino, F.′ Trans. 」apan 3oct Mecれ■ EngrS, (in Japaneee)′vo■,41, NO,34■ (1975-■), p.■70.(7)しeda, 0. and Tanaka, HI′ Trュ■s, 」 paln s。0, Mech. Bngrs, (in Japanese)′vo■.41T No.350 (■975‐■0), p.28.53.(8, Furuνlュ′ Y. and YOShino″ F.′ Transt Japan s‐oc. Mecho EngFS. (in 」apanese,,vo■.42, No,3581(1976-6), p.■aao.

The Spanwise Distributions of Characteristic Values near a Side-Wall of a Circular Cylinder with Tangential Blowing(Effect of Angular Location of a Blowing Slot)

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The Spanwise Distributions of Characteristic Values near a Side-Wall of a Circular Cylinder with Tangential Blowing(Effect of Angular Location of a Blowing Slot)

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