CFX Intro 13.0 WS02 Airfoil

7/18/2019 CFX Intro 13.0 WS02 Airfoil

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Workshop 2

Transonic Flow Over aNACA 0012 Airfoil.

Introduction to CF



WS2: Flow over an Airfoil



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Workshop Supplement !oals

%he p&rpose o' this t&torial is to introd&ce the &ser to #odelling 'lo( in

high speed e)ternal aerodyna#ic applications.

In this case the 'lo( over a NA*A 0012 air'oil at an angle o' attach o' 1.+

(ill $e si#&lated and the li't and drag val&es (ill $e co#pared to p&$lished

res&lts. %hese res&lts (ere taen (ith a eynolds n&#$er o' )10/ and a

chord length o' 1#.

%he air'oil is travelling at ach 0. so the si#&lation (ill need to acco&nt

'or co#pressi$ility as (ell as t&r$&lence e''ects.

%o red&ce the co#p&tational cost, the #esh (ill $e #ade &p o' a 2" slice

thro&gh the air'oil 3one ele#ent thic4.

NASA % 512 %(o-"i#ensional Aerodyna#ic *haracteristics o' the NA*A 0012 Air'oil in the 6angley 5-7oot %ransonic Press&re %&nnel 151.

8arris, *. ".




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"ece#$er 2010

Workshop Supplement "tart a Work#ench pro$ect

1. 6a&nch Wor$ench

2. Save the ne( pro9ect as naca0012 in yo&r(oring directory

!. "rag a Fluid Flow (CFX) #od&le 'ro# the

Analysis Systems section o' the Toolo!

onto the "ro#ect Schematic

+. In the "ro#ect Schematic right-clic on the$esh cell and select %mport $esh File

:. Set the 'ile 'ilter to F&'T Files and select

ACA0012*msh

– With the #esh 'ile i#ported the +eometry cell

(ill not $e needed so it is re#oved 'ro# theFluid Flow #od&le.

Note that yo& co&ld have dragged Component System , CFX onto the Pro9ect

Sche#atic, as in the 'irst (orshop. %he #esh (o&ld then $e i#ported a'ter

starting *7;-Pre.




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"ece#$er 2010

Workshop Supplement %esh %odification

1. <pen *7;-pre $y right-clicing on the Setup cell and

selecting dit

– A'ter *7;-Pre has opened the #esh can $e e)a#ined

and it is clear that the scale is incorrect as the air'oil

chord is 1000 # rather than 1 #, indicating the #esh

(as $&ilt in ## rather than #. %his can $e 'i)ed &sing

the #esh trans'or#ation options.

2. ight-clic on $esh in the -utline tree and selectTrans.orm $esh

!. *hange the Trans.ormation to Scale

+. 6eave the #ethod to 'ni.orm and enter a 'ni.orm

Scale o' 0*001

:. *lic -/

/. Select the Fit iew icon 'ro#

the =ie(er tool$ar

– >oo# in '&rther to see the air'oil




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%he #esh has $een $&ilt to have a single

$o&ndary aro&nd the entire o&ter edge. %his

needs to $e split into inlet and o&tlet regions.While it is $etter to create the correct #esh

regions (hen generating the #esh, *7;-Pre

can $e &sed to #odi'y the #esh regions.

1. ight-clic $esh in the -utline tree and select%nsert , "rimitie e3ion

2. *lic on the Start "ickin3 $&tton

!. 7ro# the drop do(n selection #en& select

Flood Select 3see i#age to the right4

+. In the vie(er select any ele#ent 'ro# the 'rontc&rved $o&ndary

– %he 'lood 'ill (ill select all cells (here the change

in angle is less than !0

:. *lic in the $oe Faces To 'ield and type %nlet

/. *lic -/

Inlet

Outlet




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%he re#aining section (ill no( $e

rena#ed ?<&tlet@.

1. )pand the $esh section o' the tree so

the list o' "rincipal 24 e3ions is

visi$le. Note that this list no( contains

the location %nlet 2. *lic on the region pressure .ar .ield 1

to con'ir# it is the region representing

the o&tlet

– It (ill $e highlighted in the =ie(er

!. ight-clic on pressure .ar .ield 1 andselect ename. *hange the na#e to

-utlet




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Workshop Supplement &o'ain "etup

Bs&ally the option to a&to#atically generate do#ains is active, this can

$e checed $y editing Case -ptions , +eneral in the <&tline tree.

1. *hec that Automatic 4e.ault 4omain is active the clic <C.

2. ight-clic on 4e.ault 4omain in the <&tline tree and rena#e it to Fluid

!. "o&$le-clic on Fluid to edit the do#ain settings






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%his case involves high speed aerodyna#ics so it is i#portant to incl&de

co#pressi$ility.

It is i#portant to set the correct operating press&re so that the intended eynolds

n&#$er is achieved. %he si#&lation (ill tae place at 255 DCE in airF this allo(s the

speed o' so&nd to $e calc&lated. %his can then $e converted into a 'ree-strea#

velocity &sing the ach n&#$er. Bsing the de'inition 'or eynolds n&#$er the 'l&id

density can $e o$tained, (hich can then $e &sed to deter#ine the operatingpress&re 'or the si#&lation, ass&#ing an ideal gas.

][56867288287688.0

]/[688.0112.238

82.19ReRe

]/[12.23817.3407.0

]/[17.3402882874.1

356

Pa RT P

mkg ee

ul

ul

smc M u

sm RT c

=××==

=

×

×==⇒=

=×=×=

=××==

−

ρ

µ ρ

µ

ρ

γ c GSpeed o' so&nd

GHas *onstant

5 Gatio o' speci'ic heatsT G%e#perat&re

uG 7ree-strea# velocity

$ Gach n&#$er

eGeynolds n&#$er

6 G "yna#ic viscosity

7G "ensity




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In the Fluid do#ain 8asic Settin3s ta$

1. Set the aterial to Air %deal +as

2. Set the e.erence "ressure to 9:;:< ="a>

– ae s&re yo& change set the &nits

!. ove to the Fluid $odels ta$

+. Set the ?eat Trans.er -ption to Total ner3y

– %his is reJ&ired 'or co#pressi$le si#&lations

:. na$le %ncl* iscous Work Term

– %his incl&des visco&s heating e''ects

/. Set the Turulence -ption to Shear StressTransport

. *lic -/






"ece#$er 2010

Workshop Supplement (oundar) Conditions

An o&tlet relative press&re o' 0 DPaE (ill no( $e applied. %his press&re is relative

to the operating press&re o' :/5/ DPaE.

Asolute "ressure @ e.erence "ressure elatie "ressure

1. ight-clic on the do#ain Fluid in the <&tline tree and select %nsert , 8oundaryB

na#ing the $o&ndary -utlet

2. *hange the 8oundary Type to -utlet and chec that the location is set to -utlet

!. ove to the 8oundary 4etails ta$ and set the $ass and $omentum option to

Aera3e Static "ressure (ith a val&e o' 0 ="a>

+. *lic -/

%he sides o' the do#ain (ill &se sy##etry conditions since this is a 2"

si#&lation.

1. Insert a Symmetry $o&ndary called Sym &e.t , at the location sym le.t

2. Insert a Symmetry $o&ndary called Sym i3ht , at the location sym ri3ht






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%he #esh has $een constr&cted so that the air'oil is at 0 angle o'

attac. %o apply the reJ&ired angle o' 1.+ the 'lo( direction at the inlet

#&st $e ad9&sted. %he val&es (ill $e created &sing e)pressions.

1. ight-clic on !pression in the tree and select %nsert , !pression. *all

it 'in. .

2. Set the 4e.inition to 2;*12 =m sDE1> then clic Apply – All e)pressions #&st have the appropriate di#ensions

!. In the e)pression editor add the 'ollo(ing e)pressions $y right-clicing

on !pressions and selecting %nsert , !pression

A-A @ 1*G=de3>

'! @ 'in.Hcos(A-A)

'y @ 'in.Hsin(A-A)

+. et&rn to the #ain <&tline tree






"ece#$er 2010


1. ight-clic on Fluid and insert a $o&ndary

called %nlet

2. %he 8oundary Type sho&ld $e set to %nlet $y

de'a&lt and a &ocation o' %nlet sho&ld also

$e selected $y de'a&lt

!. ove to the 8oundary 4etails ta$

+. *hange the $ass and $omentum option toCart* el* Components

:. nter the B, = and W val&es as '!B 'y and

0 =m sDE1>

– Bse the )pression icon to allo( the '!

and 'y e)pressions to $e entered/. Set Static Temperature G 2;; =/>

. *lic -/




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%he =ie(er indicates the locations o'

the inlet and o&tlet $o&ndaries. Note

that the arro(s do not represent the

applied 'lo( direction.

%he 'inal $o&ndary condition is the (all

aro&nd the air'oil. %his sho&ld alreadye)ist as Fluid 4e.ault .

1.dit Fluid 4e.ault to chec that only the

wall ottom and wall top regions re#ain

in the de'a&lt $o&ndary2.*lic Close

!.ena#e Fluid 4e.ault to Air.oil




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"ece#$er 2010

Workshop Supplement %onitors

7or this si#&lation the li't and drag are the J&antities o' interest, so #onitor points

(ill $e added to trac their val&es and ens&re they reach a steady val&e. %he li't

and drag coe''icients (ill $e created &sing e)pressions. e#e#$er that the 'ree-

strea# 'lo( is o''set 'ro# the )-direction so the 'orces (ill have to $e ad9&sted to

acco&nt 'or the angle o' attac.

1.nter the 'ollo(ing e)pressions, or select

File , %mport , CC& and load the 'ile Air.oil*ccl . I' loading the **6 'ile, &se

the Append option as sho(n

[email protected]()JAir.oil

[email protected]!()JAir.oil

&i.t @cos(A-A)HFyEsin(A-A)HF!

4ra3 @cos(A-A)HF! sin(A-A)HFy

4enom@0*9HmassFlowAe(4ensity)J%nletH'in.D2H1=m>H0*1=m>

c&@&i.tK4enom

c4@4ra3K4enom




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"ece#$er 2010

Workshop Supplement %onitors

1. dit -utput Control 'ro# the -utline tree and go to the $onitor ta$

2. *hec the $onitor -ptions $o)!. *lic on the Add ew Ite# icon and na#e it C&

+. Set the -ption to !pression and enter c&

– %his is the #onitor point 'or the *oe''icient o' 6i't. Note that all na#es and

e)pressions are case sensitive, so the #onitor point is na#ed ?*6@ and it

re'ers to the e)pression na#ed ?c6@.:. Add a ne( ite# called C4 and set it to the e)pression c4

– %his is the *oe''icient o' "rag

/. *lic -/




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Workshop Supplement "olver Control

<pen the Soler Control section 'ro# the

<&tline tree

1. Increase the $a!* %terations to 200

2. *hange the Timescale Factor 'ro# 1 to 10

– A larger ti#escale can accelerate

convergence, $&t too large a ti#escale (ill

ca&se the solver to 'ail

!. Set the esidual Tar3et to 1eE:

– %his is a tighter convergence criteria and is

disc&ssed '&rther $elo(

+. *lic -/

:. %his case is no( ready to r&n so clic onFile , Sae "ro#ect then close the *7;-Pre

(indo( to ret&rn to the #ain Wor$ench

(indo(






"ece#$er 2010

Workshop Supplement *unnin+ the "i'ulation

1. In Wor$ench right-clic on Solution and select 'pdate

2. A'ter the solver has started right-clic on Solution again and select4isplay $onitors

– %his (ill open the Solver anager and allo( the resid&als and #onitors to

$e vie(ed

!. *hec thro&gh all o' the resid&als and #onitor val&es. %he val&es o' *"

and *6 $eco#e steady a'ter a$o&t :0 iterations. Yo& can clic the Stop

$&tton 'ro# the tool$ar to stop the r&n at this point.

In the Solver anager the 'ser "oints ta$ displays the #onitor points set&p

in the -utput Control section o' *7; Pre. %his (ill incl&de the val&es o' C& and C4. %hese sho&ld converge to a steady val&e $e'ore the convergence

criteria is #et. <ther(ise the r&n sho&ld $e e)tended. any cases (ill $e

converged (hen an S resid&al level o' 1e-+ is reached. 7or this case this

is inadeJ&ate since the li't and drag had not reached steady val&es (hen

the resid&als (ere at 1e-+, hence a tighter convergence criteria (as &sed.






"ece#$er 2010

Workshop Supplement %onitor ,alues

Ke'ore e)iting the Solver anager the

converged val&es o' *6 and *" can $e

vie(ed $y clicing on the #onitor lines.

%he val&es e)tracted sho&ld $e *6G0.2!/

and *"G0.0052. %hese val&es co#pare

(ell to p&$lished val&es o' *6G0.2+1 and*"G0.00.

No( close the solver and ret&rn to the

Wor$ench (indo(.

AIAA-5-0+1/ N&#erical Si#&lation o' =isco&s %ransonic Air'oil 7lo(s 15. %ho#as L

*oaley, NASA AS esearch *entre.






"ece#$er 2010

Workshop Supplement -ostprocessin+

1. ight-clic in the esults cell and select

dit to open *7"-Post. %he res&lts

sho&ld a&to#atically $e loaded

%his case reJ&ired a large do#ain to

allo( the $o&ndary conditions to $e

i#posed (itho&t a large arti'icial

restriction on the 'lo(. 8o(ever d&ring

post-processing the #ain interest (ill $e

in the 'lo( close to the air'oil.

2. *lic on the >-a)is in the $otto# right

corner o' the =ie(er to orientate the vie(

!. Bse the $o) Moo# 3right #o&se $&tton4

so the =ie(er displays the region aro&nd

the air'oil






"ece#$er 2010


When looing at the 'lo( aro&nd an air'oil,

plots o' several varia$les can $e o' interest

s&ch as velocity, press&re and ach n&#$er.

1. In the tree t&rn on the visi$ility o' Sym &e.t $y

clicing in the chec $o)

2. "o&$le-clic on Sym &e.t to $ring &p thedetails section

!. Bnder the Colour ta$ change the #ode to

ariale and select elocity &sing the +loal

ange, then clic Apply

Notice that the #a)i#&# velocity is aro&nd

!:0 D#sE. %his is higher than the sonic speed

o' !+0 D#sE calc&lated earlier 'or 'ree-strea#

conditions.






"ece#$er 2010


%o plot the ach n&#$er a conto&r plot (ill

$e &sed so the s&personic region can clearly

$e identi'ied.

1. Select %nsert , Contour or clic on the conto&r

icon

2. Accept the de'a&lt na#e then set &ocations toSym &e.t and the ariale to $ach umer

!. *hange the an3e to 'ser Speci.ied and

enter 0 to 1*1 as the range

+. Set L o. Contours to 12 , then clic Apply

:. %&rn o' the =isi$ility o' Sym &e.t so that theprevio&s velocity plot is hidden

/. %ry plotting other varia$les s&ch as Press&re

or "ensity, &se the 6ocal or Hlo$al ange

(hen li#its are not no(n






"ece#$er 2010


%o plot the press&re coe''icient distri$&tion aro&nd the air'oil a

polyline is needed to represent the air'oil pro'ile and a varia$le

needs to $e created to give *P.

1. *reate a Polyline &sing &ocation , "olyline 'ro# the tool$ar

2. *hange the $ethod to 8oundary %ntersection

!. Set 8oundary &ist to Air.oil +. Set %ntersect With to Sym &e.t and then clic Apply

:. %&rn o'' visi$ility o' the previo&s created *onto&r plot to see the

Polyline

A line (ill $e created aro&nd one end o' the air'oil. 7or '&ll !" cases

;Y planes can $e create at vario&s span locations and &sed to

e)tract Polylines.

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:. ove to the !pressions ta$ and right-clic to create a ne(

e)pression na#ed c" (ith the de'inition

"ressureK(0*9HmassFlowAe(4ensity)J%nletH'in.D2)

/. ove to the ariales ta$ and right-clic to create a ne( varia$le

na#ed C" .

. Set the $ethod to !pression and select c" . *lic -/ .

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A chart sho(ing the press&re distri$&tion aro&nd the air'oil (ill no( $e

created.

1.Insert a chart &sing %nsert , Chart or selecting

2.In the +eneral ta$ leave the type as XM

!.ove to the 4ata Series ta$ and enter a ne( series. Set the location to

"olyline 1

+.ove to the X A!is ta$ and change the varia$le to X

:.ove to the M A!is ta$ and change the varia$le to C"

/.*lic Apply and the chart is generated

%hese val&es can $e co#pared (ith e)peri#ental res&lts.

AIAA-5-0+1/ N&#erical Si#&lation o' =isco&s %ransonic Air'oil 7lo(s 15. %ho#as L *oaley, NASA AS esearch *entre.

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"ece#$er 2010


. et&rn to the 4ata Series ta$ and change the

na#e to CFX

5. Insert a ne( series and give it the na#e

!periment

. *hange the 4ata Source to File and select the

'ile C"*cs

10. <n the &ine 4isplay ta$, set &ine Style toone and Symols to ectan3le. Also ens&re

that Symol Colour is a di''erent colo&r 'ro#

the c&rrently plotted *7; line

11. *lic Apply and $oth data series are dra(n

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WS2-2/ ANSYS, Inc. Proprietary


"ece#$er 2010

Workshop Supplement "u''ar)

%he (orshop has covered

O 6oading an e)isting #esh

O Scaling the #esh

O Henerating Ne( egions 'ro# e)isting 2" Pri#itives

O Setting &p and r&nning a high speed co#pressi$le 'lo( si#&lation over

an air'oil

O )tracting li't and drag 'orces and co#paring (ith e)peri#ental data

O )a#ining the 'lo( patterns aro&nd the air'oil

O *o#paring the press&re distri$&tion to e)peri#ental val&es

WS2 Fl Ai f il




ANSYS Inc Proprietary elease 1! 0

Workshop Supplement "cope for further work.

%his si#&lation is a good #atch to e)peri#ental (or $&t '&rther steps

co&ld $e taen i' reJ&ired, incl&ding

O e'ining the #esh, partic&larly in the (ae region.

O Applying a transition #odel to acco&nt 'or the s#all region o' la#inar 'lo(

aro&nd the nose o' the air'oil.

O Adding additional air'oil 'eat&res s&ch as a 'inite thicness trailing edgethat (ill $e &sed on all ?real air'oils@.

O Si#&lating the (hole (ing to acco&nt 'or span(ise variations.

Adding #ore 'eat&res to a si#&lation (ill &s&ally increase the

co#p&tational cost, so one o' the #ost i#portant step in any si#&lation is

to decide (hich 'eat&res need to $e incl&ded and (hich can $e le't o&t.

CFX Intro 13.0 WS02 Airfoil

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