Low Reynolds number airfoil survey, volume 1

105 Pages·2015·5.13 MB·English

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https://ntrs.nasa.gov/search.jsp?R=19820006186 2019-03-26T13:04:40+00:00Z
NASA Contractor Report I05003
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LOW REYNOLDNSUMBER/_IRFOILSURVEY
VOLUMEI
B. H. Carmichael _(
LOW ENERGYTK_NSPORTATIONSYSTEMS /
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PREFACI:
Tile1ocatlmland cnllm:timl_f tim.lar_]em_,h_)raf _mefulreferences
p(_rtalnint.oq thlsl_Ighlysp_:_l_11zefdi_,Idwas _.xpmllt_tdhr(}ll_tlhhe 1
golmrou_and wholelleartecdo_p_.ratio_nf many enthuslastlcres_.;arcllers.
The extensive_irf(}idlo_i_nalldt_.stil1b.yqlI)'_A.ltl_aus,Epplerand j
!
Wortm_mnof StuttgartUniversity,thoseof Dr. wm Inge,and his associ_ites
at DelftUniversity,The Netherlands,_md thoseof Dr. Muel]Qra,d his
associatesat the Universityof NotreDame are currentand most useful.
AlthoughNASA Langleyis not activein the criticalReynoldsnumberfield,
,!
discussionswith Dr. Pfennlnger,H. Phillips,and Dan Seinersand Harry i
Sheafof thatfacilityhave beenhelpful. Additionalusefuldata have
06
beenobtainedthrl_ugDhr. Kramerof GottingenUniversity,Dr. Marsdenof
the Universityof Alberta,Dr. Mileyof TexasA&M,Dr. E(.Ig!estoofn the
Universityof WesternOntarlo_ Larrabeeand Derilla of Mas._achusettS
Instituteo'_Technology,a_d Patrickof CranfieldUniversity.
Aid was also receivedfrom Zipkinand Dr. Roy Smithof GeneralElectric
Corporation.JolmMcMastersof BoeingAircraft,Bob Liebeckof Douglas
Aircraft,and RussOsborn_of WrightField
The scientificfree flightmeasurementsof modelaircraftbuilders,
MaxlmilllanHacklingerof Germany.[illbertHoffmann,Andy Buaer,and "
BlainRawdonof the UnitedStateshave been inspiring°
Meeting_nd talkingwith FrankZaic,whoseModelAircraftYearbooks
havedisseminatedthe latesttechnologyto modelaircraftbuildersthrough-
out theworldfor half a centurewas a greatjoy and prlvilege. Discusslons
and c_)rrespondencweltl_expertmodel builderssu_:has Blanchard,¢hampine,
*!
Gioskleng,Gale.,* llmman,Hines,Isaacson,Mouser,Meier,Ko, Pressnell,
i i
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Reld,WagnerW,hite,and Xenakishaveh_Ipedtomaketh_limltati_s
of laboraturdyevelopedmaximump_rfo_anceairfoilswhenenceunterlng
therealworldaf rouohalrdynamicfreefllghtpalnfullyclear, The
keenobservationaplowerBandempiricaldevelopmentb_y freeflight :;I
modelbuilder_havealreadyarrivedat a hlghtechnlcalplateau,
ii
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c.\
-)
L_O_,._REYNONL.DUS.MBEA_IRRFOILDA_TAsU. RVE_y
TABLE.OFCONTENT_S
Listof Illustrations v
Nom(_ncalture vli
ix
Sumnlary
I BrlofReviewof ApplicableAerodynanliPcrinciple_ I
II Changesin Flow Phenomenaand Wing DesignTechnique 7
With Inc,'easinRgN
FlowPhenomenaBibliography 14
Iil S.tateof Knowledgeon FluidFlowSeparation 15
Introduction 15
Chronology 16
Discussion 19
FlowSeparationBibliography 43
IV Low ReynoldsNumberAirfoilCharacteristics 46
(A) LaboratoryTestData 46
HistoricalReview 46
Chronology 53
Discussion 57
Bibliography 67
(B) Discussionof Free FlightTesting 71
Chronology 73
FreeFlightBibliography 75
(C) Low ReynoldsNumberAirfoilDesign 77 :
AirfoilDesignBibliography 81
(D) Bookso_ TechnicalAeromodelling 84
V BoundaryLayerTrippingDevices 85 '
(A) HistoricalReview 85
(B) VariousMethodsof BoundaryLayerTripping 86 !
(C) Uiscussion 88
(D) Bibliography 96
iii
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PREOEDINGPAGEBLANKNOT
Listof lllgstratlQns
II-I- TheRealmof Reynolds 8
III-1 - LaminarBubbleGeometry 28
-= - SchematicDiagramof LaminarSeparation Bubble 29
-3 - t.amtnarSeparation Prediction 30
-4 - Reparation Streamline Angle 31
-5- SeparationStreamlinAengle 32
-6- TransitionBubbleLength 33
-7 - LaminarPart of BubbleLength 34
-8- TotalBubbleLength 35
-9- CriticalBurstingPressureCoefficient 36
-10-BubbleEffectson PressureDistribution 37
-11-BoundaryLayerVelocityProfile 38
-12-BubbleLengthvs.ROs 39
-13-TransitionCriteriaBasedonBubbleHeightandRN 3g
-14-VelocityDistributionisnSeparationBubble 40
-15-PressureDistributioonverSeparatedRegion 41 ,!
-16-VariationinShapeFactorH =_*/0 41 il
-17-Comparisoonf CalculatedVelocityDistributions 42 ii
i
IV-I- AerodynamiCcompariSonofTurbulentTunnelData 47 .
(withRN increasedtoaccountforturbulence)with
lowturbulencteunneldata) _'_
-2- Liftvs DragandLiftvsdForms 59
-3- Eppler61 AirfoilinThreeWindTunnelsat RN = 50,000 61
-4 - Eppler61AirfoilinThree WindTunnelsat RN= 80,000 63
-5 - Comparisonof Eppler387ExperimentaPlolarsWith 79
TheoreticaPlredictions
V
•-,'-.
=.._: ._',
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V-1 - Various Methodsof Boundary Layer Tripplng B7
-2 - Effect of Soundand T.rip Wire on E-51 at Rc - 80,OOD 93
-3 - Effectof Soundand TripWire on E.61at Rc = 50,000 g4
-4 - Effectof SoundPressureLevelon Lift in CriticalRange g5
vi
................. "" •" :'. _':'.'.i"-/-."" ._". " ' ' _t.5"- .... "-'-"" , ....,, • .,-........ "
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N_enclature
rSYMBOL DESCRIPTION UNITS • •
't.........
c atrFotl chord length ft.
CB drillc.oIe,fficient_ Dlq .S
CL llftcoefficient_,L/q •S
CM pitchingmonlentcoefficient= M/q .S , c
Cp pressurec(_efflcien_t (Pl " Po)/q
Ow wettedareadrag coefficient= D/q . Sw
D drag pounds
f camberor maximummean lineheightabovechord..1-ine c
g accelerationof gravity ft/sec2
ht heightof bubbleat _ransltien ft.
l Iength ft.
L Iift pounds
Lb totalbubblelength _ ft.
m velocitygradientparameter= Yg- cJ.U
WK
M pitching moment ft.pounds
Pl localsurfacepressure pounds/ft2
Po ambit pressure _ pounds/ft2 •
q fIlghtdynamicpressure= _U=_ pounds/ft2
R reattachmentpoint
Rs arc lengthReynoldsNo. U ._"
= _
RN chordReynoldsNo. : Rc : U_v,_ii
Rtl momentumthicknessReynoldsNo. : --_
R% % at separationpoint: ..J,L._
s arc lengthfromstagnationpoint ft.
S wingarea ft2
vii
i. !
(
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NomenclatureConttnued
SYMBOL DESCRIPTION UNITS
Sw wetted_rea ft2
SPL soundpressure level db
t maximumairfollthickness ft.
T transitionpoint
Tu turbulencelevel 'XIJ,_
_i velocityat heighty in the boundarylayer ft/sec
U velocityat outsideedge of the boundarylayer ft/sec
U=, flight velocity ft/sec
V spanwise velocity ft/sec ,
X distancealongstrean}direction ft.
AX laminarportionof bubblelength ft.
y distancenormalto surface ft.
_ angleof attack- betweenchordline& relativewind deg.
^ incrementof distance ft.
6
_* displacementthickness:_ (I- "_) ¢J_' ft. ,
s _ ¢jy 1
II momentumthickness= J"-_(/ "O'J ft.
y separationstreamlineanglefromsurface deg. .,
o pressurerecoverycoefficient- I -
p fluid density pounds sec2
ftq
_l absoluteviscosity op_o_u_sPe,c_ds
---fr+t:-Z-----
v kinematicviscosity ft2/sec
viii
:1:2,
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SUMMARY
Experimental_erodynamicpropertiesQf two dlmensionalalrfol1._in
the critlcalehordl_n,qtRheynold_numberrar}qebetween40,000and 100,000
havebeen gathor,ed fromsourcesIn nine countriesof'theworldand from
a sevendecadetlme period, The differencesIn 'Flaw_havior in this
re!ilmecomparedwlth lowerand higherReynoldsnumbersare dlscus._d,
Informationon flowseparation,in partlcqlar,the largelamlnarseparation
bubbleis discussedIn detailin view of Its importantinfluenceon critical
Reynoldsnumberairfoilbehavior, The shbrtcomingsof applyingtheoretical
boundarylayercomputationsfoundsuccessfulat higherReynoldsnumbersto
tte, criticalregimeare discussed. The largevariationIn experimental
aerodynamiccharacteristicneasurementrideto smallchangesin amblent
turbulence,vibration,and soundlevelis._..]lustrawtletdh experlmentaldata.
The variationin resultsfromthe bestavailablelaboratoriesand the
problemof realistic laboratorvsimulatio,of freefliqhtconditlonsis made
clear. The difficultiesin obtainingaccuratedetailedmeasurementsin
freeflightare discussed.
Dramaticperformanceimprovementsat criticalReynoldsnumber,achieved .,
I
with varioustypesof boundarylayertrippingdevicesare discussed, !
i
The includedchronologiesand bibliographiesare intendedto be the :i
"1
most completeavailableon thissubject,
The aerodynamicparametersof airfoilsin the csiticalReynolds
numberrangewill be comparedin the secondvolumeof this study.
ix
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I .BRIEFR.EVIEW_OFAPPL.,!CABAbEER,ODYNAMIPCRINCIPLES
Boundary_Laye_tr
A comparativeltyhin_heet of decelerated fluidoriginatintghrough
frictionalongthesurfaceof solids,
Bound__L_____a_aa_r-_y?L_armlnar
Theconditionfoundat lowerReynold_numbersinwhichinterchange
of momentumbetweenadjacentboundary_ayorlevelsdoesne_._.toccur_
Surfacefrlctionandflowgeneratednoiseare lowcomparedto---
BoundaryLayer- Turbulent
Theconditionfoundat higherReynoldsnumbersinwhichinterchange
ofmomentumbetweenadjacentboundarylayerlevelsdoesoccur,
Surfacefrictionandflowgeneratednoisearehighcomparedto the
laminarcondition.
CoefficienotfLift
Theliftforce(L)of a wing,non-dimensionalizoendthebasisof CL =L__o.q.L__-
projectedwingarea(S)andflightdynamicpressure(q).
Coefficienotf Drag- Profile
Thedragforce(D)of a wing,non-dimensionalizoendthebasisof
projectedwingarea(S)andflightdynamicpressure(q). CD =
Coefficienotf Drag- Wetted
Thedragforce(D)ofa wing,non-dimensionalizoendthebasis =D._.D___
CW sw.q
ofwettedareaSW = 25andflightdynamicpressure(q).
Coefficienotf Mome,nt
Thepitchingmoment(M)of a wing,non-dlmensionallzoendthe M
basisof projectewdingareaS,wingchordc,andfiightdynamic CM =
pressure(q),
L
, I ............... "' "" *_ I__' I-I """