saverrrr333

TutorialforXFoilDownloadXFoilDownloadXFoilfromhttp://raphael.
mit.
edu/xfoil/.
Itwouldbeagoodideatodownloadthedocumentationforfuturereferenceaswell.
InstallingXFoilCopythedownloadedfiletothedirectorywhereyouwanttoinstallXFoilandrunit.
RunningXfoilXFoilisexecutedbygoingtothedirectorywhereitwasinstalledandtyping%xfoilLoadinganAirfoilTheloadorNACAcommandcanusedtoloadanairfoilintoXFoil.
InthistutorialwewillbeusingaNACA2412airfoil.
ToloadthisairfoiltypeXFOILc>NACA2412NoticethatXFoilwillreturnsomeofthespecificationsfortheairfoil,includingthelocationandmagnitudeofthemaximumthickness,maximumcamber,andotherparameters.
CleaningtheAirfoilGeometryItisagoodideatoensurethattheairfoilloadeddoesnotcontainpanelsthatcreateverysharpedges.
ThePANEcommandinXFoilsmoothesouttheairfoilgeometry.
XFOILc>paneNOTE:ThecommandsarenotcasesensitiveTheOPERSub-LevelTypeXFOILc>OPERThiswillproducetheprompt.
OPERic>Typea""toseealistofavailablecommandsandabriefdescriptionoftheiruse.
ThisworksonanylevelofXFoil.
IntheOPERlevelthisiswhatyouwillseeaftertyping""ReturntoTopLevelRedolastALFA,CLI,CL,ASEQ,CSEQ,VELSViscrToggleInviscid/Viscousmode.
VPARChangeBLparameter(s)RerChangeReynoldsnumberMachrChangeMachnumberTypeiChangetypeofMach,RevariationwithCLITERChangeviscous-solutioniterationlimitINITToggleBLinitializationflagAlfarPrescribealphaCLIrPrescribeinviscidCLClrPrescribeCLASeqrrrPrescribeasequenceofalphasCSeqrrrPrescribeasequenceofCLsSEQPTogglepolar/Cp(x)sequenceplotdisplayCINCToggleminimumCpinclusioninpolarHINCTogglehingemomentinclusioninpolarPacciToggleautopointaccumulationtoactivepolarPGETfReadnewpolarfromsavefilePWRTiWritepolartosavefilePSUMShowsummaryofstoredpolarsPLISiListstoredpolar(s)PDELiDeletestoredpolarPSORiSortstoredpolarPPloii.
Plotstoredpolar(s)APloii.
Plotstoredairfoil(s)foreachpolarASETiCopystoredairfoilintocurrentairfoilPREMir.
Removepoint(s)fromstoredpolarPPAXChangepolarplotaxislimitsRGETfReadnewreferencepolarfromfileRDELiDeletestoredreferencepolarGRIDToggleCpvsxgridoverlayCREFTogglereferenceCpdataoverlayFREFTogglereferenceCL,CD.
.
datadisplayCPxPlotCpvsxCPVPlotairfoilwithpressurevectors(geewiz).
VPloBLvariableplots.
ANNOAnnotatecurrentplotHARDHardcopycurrentplotSIZErChangeplot-objectsizeCPMIrChangeminimumCpaxisannotationBLiPlotboundarylayervelocityprofilesBLCPlotboundarylayervelocityprofilesatcursorBLWTrChangevelocityprofilescaleweightFMOMCalculateflaphingemomentandforcesFNEWrrSetnewflaphingepointVELSrrCalculatevelocitycomponentsatapointDUMPfOutputUe,Dstar,Theta,Cfvss,x,ytofileCPWRfOutputxvsCptofileCPMNReportminimumsurfaceCpNAMEsSpecifynewairfoilnameNINCIncrementnameversionnumberNoticethattherearethreecolumns,thefirstisthecommand,thesecondonegivesanindicationofotherinputsthecommandneeds.
An"r"meansthatthecommandexpectsarealnumber,an"i"meansthatthecommandexpectsaninteger,an"f"meansthatthecommandexpectsafilename,andan"s"thatthecommandexpectsastring.
IftheinputisnottypedafterthecommandXFoilwillprompttheuser.
XFoilUnderInviscidModeNoticethe"i"nextto".
OPER"ontheprompt.
ThisindicatesthatXFoilisininviscidmode.
Type.
OPERic>alfa0XFoilwillfindtheflowaroundtheairfoilforthegivenangleofattack,inthiscase,0.
Noticethatawindowpopsupshowingthepressuredistribution,thesectionliftcoefficient,thesectionmomentcoefficient,theangleofattackandtheairfoilname.
Figure1.
CpDistributionatalpha=0Type.
OPERic>cl0.
7XFoilwillfindtheangleofattackatwhichthecurrentairfoilproducesthesectionliftcoefficientthathasbeeninput.
NoticethatXFoilonceagainplotsthepressuredistributionaroundtheairfoillikeitdidpreviously.
Figure2.
PressureDistrubionatCl=0.
6ViscousModeType.
OPERic>viscThiscommandwillturnontheviscousmode.
XFoilthenpromptstheusertoinputaReynoldsnumber.
ForthistutorialwewillworkwithalowReynoldsnumber,type"3e6"attheprompt.
Noticethata"v"willnowappearnextto"OPER"intheprompttoindicateviscousflow.
Tofindtheflowaroundtheairfoilatanangleofattackofzerodegreestype.
OPERvc>alfa0Noticethatnowthereseemtobetwopressuredistributions.
Thedashedlinesrepresenttheinviscidflowdistribution.
Thisprovidesaneasywaytocompareviscousandinviscidflow.
Figure3.
ViscousFlowAroundanAirfoilNoticealsothattheboundarylayerisoutlinedaroundtheairfoil.
Furthermore,thecoefficientofdragandthelift-to-dragratioarealsopresented.
Ifyoulookatthecommandscreen,thelastiterationalsoprovidesmoredataabouttheairfoil:Side1freetransitionatx/c=0.
527446Side2freetransitionatx/c=0.
3940386rms:0.
1349E-04max:0.
1462E-03Cat382a=0.
000CL=0.
2422Cm=-0.
0527CD=0.
00545=>CDf=0.
00466CDp=0.
00079Itprovidesthepointoftransitiontoturbulentflowintheupperandlowersurfaces.
ItalsoprovidesCDfandCDp,thefrictiondragandpressuredragrespectively.
GettingaHardCopyTogetacopyinpostscriptformatofthedisplayedplottype.
OPERvc>hardAcopywillbeproducedontheXFoildirectoryunderthefilenameplot.
ps.
YouwillnotbeabletoopenthisfileuntilyouexitXFoil.
However,anyotherfilesthatyouhardcopywillbeappendedtothefileplot.
ps.
ChangingthenumberofiterationsType.
OPERvc>alfa18YouwillnoticethatXFoildoesnotconverge.
Thisisbecauseitreachedthemaximumnumberofiterations.
Therearetwodifferentthingsthatcanbedone.
Type"!
",thiscommandwilltellXFoiltoiteratesomemore.
AsyoucanseeXFoilwillnotconvergeevenafteryoudothisonce.
Youcankeeptyping"!
"untilXFoilconvergesoryoucantrychangingthemaximumnumberofiterations.
Type.
OPERvc>iterApromptwillaskyoutoenterthenumberofiterations,type"100".
Thentype.
OPERvc>alfa18YouwillnoticethatXFoilwillconvergeafterabout54moreiterations.
ChangingtheCpminNoticethatatanangleofattackof18degreestheminimumCpislowerthan-2,thedefaultCpmin.
Type.
OPERvc>cpmnThiswilldisplaytheminimumCpdistributionMinimumInviscidCp=-17.
2591atx=0.
0004MinimumViscousCp=-12.
1387atx=0.
0010Type.
OPERvc>cpmi-18Tore-plottheCpdistributiontype.
OPERvc>cpxTheCpdistributionshouldnowlooklikethis:Figure4.
FlowAroundanAirfoilataHighAlphaSavingtheCpDistributiontoaFileType.
OPERvc>cpwrYouwillbepromptedtoenterafilename.
Enter"naca2412@18.
cp".
ThefilewillbesavedintextformatanditispossibletouseMATLABtoanalyzethedata.
RunningXFoilforaSeriesofAnglesofAttackType.
OPERvc>alfa0Then.
OPERvc>paccThiswillcreateafiletowhichthesectionliftcoefficient,thesectiondragcoefficient,theupperandlowertransitionpointsandotherdatawillbesaved.
Thiscommandalsoenablestheautopointaccumulation.
Youwillbepromptedtoenterafilenameforthenewlycreatedpolarfile.
Type"naca2412.
pol".
PressEnterwhenpromptedforapolardumpfilename.
Nowtype.
OPERvac>aseq020.
5ThiscommandwillrunXFoilforaseriesofanglesofattack,from0to20degreesat0.
5degreeincrements.
Type.
OPERvac>paccThiswillturnoffthepointaccumulation.
Thefile"naca2412.
pol"willbeinatextformatandcanbereadbyMATLAB.
ChangingthePointofTransitiontoTurbulentFlowType.
OPERvc>alfa0Thelastiterationwilllooklikethis:Side1freetransitionatx/c=0.
527446Side2freetransitionatx/c=0.
3940383rms:0.
8854E-04max:0.
1737E-02Cat382a=0.
000CL=0.
2422Cm=-0.
0527CD=0.
00545=>CDf=0.
00466CDp=0.
00079Noticeonthecommandwindowthatthepointoftransitionoftheuppersurface(Side1)isatx/c=0.
5274.
Letforcetransitionatx/c=0.
1.
Type.
OPERvc>vparThiscommandwillmoveyouintotheVPARsub-levelType.
.
VPARc>xtr0.
11Thiscommandwillforcetransitionatx/c=0.
1fortheuppersurfaceandx/c=1atthetopsurface(whichisthesameasfreetransition).
PressentertomovedowntotheOPERsub-level.
Type.
OPERvc>alfa0Thelastiterationwillnowlooklikethis:Side1forcedtransitionatx/c=0.
100022Side2freetransitionatx/c=0.
3824373rms:0.
6169E-05max:0.
1369E-03Cat372a=0.
000CL=0.
2238Cm=-0.
0499CD=0.
00763=>CDf=0.
00630CDp=0.
00133Noticethattransitionnowoccursatx/c=0.
1likeexpected.
Youcanalsoseethedifferenceinthesectiondragcoefficients.
QuittingXFoilPressenteruntilyoureturntothetoplevel,thentypeXFOILc>quit