As part of a NASA/DFVLR cooperation program two transonic airfoils were tested in the NASA Langley 0.3-m TCT. Model design and construction was carried out by DFVLR. The models designed and constructed performed extremely well under cryogenic conditions. Essentially no permanent changes in surface quality and geometric dimensions occurred during the tests. The aerodynamic results from the TCT tests which demonstrate the large sensitivity of the airfoil CAST 10-Z/DOAZ to Reynolds number changes compared well with results from other facilities at ambient temperatures

Ludewig, K. H.

Ray, E. J.

Schaechterle, G.

Stanewsky, E.

English

NASA Technical Reports Server

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I
ETW CRYOGI:NIC TECHNOLOGY REVIEW MEETING A!IJ ~/J ""'-/YJ_ r7.r-::?.., K
AMST'\.-"IDAM,· SEPT. 15-17, 1982 /vfiJI1 1/1/ l)~JL.-)
----
Design and Construction of Two Transonic Airfoil Models
for Tests in the NASA Langley O.3-MoTCT
by
NASA-TM-85325 19830015055
and
E. J. Ray
NASA Langley
.
G. Scpachterle, ~.-H. Ludewig, E. Stanewsky
DFVLR-AVA G6ttingen
Summary: As part of a NASA/DFVLR cooperative program two tran~
- "
sonic airfoils were tested in the NASA O.3-Meter Transonic
Cryogenic Tunnel. The design and construction of the models was,
guided by NASA expericence, carried ~ut by DFVLR. The present
paper mainly covers matters related to model design and construc-"
tion.This is ~up;plemented by some" aerodynamic test results.
1. INTRODUCTION
" "
Recognizing the need for high Reynolds number research at t
transonic speeds and realizing that high Reynolds numbers are
.. most practicably be obtained by low temperatures, a cooperative
program with NASA La~ey was initiated testing two transonic
A .
airfoils, viz., the Dornier design CAST 10-2/DOA2 and the
DFVLR-R4 in the Langley O.3-Meter Transonic Cryogenic Tunnel.
Specific objectives were
" "
- to gain experience in model design, fabrication and testing
under cryogenic conditions
- to determine the Reynolcs number dependence of the flow develop-
ment on a special c·lass of transonic airfoils and
. I
~-'to correlate O.3-M TCTresults with results from other major
two-dimensional test facilities.
1
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••
In accordan~e with the first objective, the model design and
construction was, guided by NASA experience, carried out by
DFVLR.
This contribution mainly covers matters related to model design
and construction. However, as supplement, some aerodynamic test
results demonstrating the Reynolds number sensitivity of one of
the airfoils investigated and comparing TCT-data with results
from other facilities are given.
2. MODEL DESIGN AND CONSTRUCTION
For the first time the Technical Services Gottingen of the DFVLR
were requested to design and fabricate an airfoil model equipped
with a large number of pressure orifices for tests under cryo-
genic conditions. As a first step all available information
about experiences in the construction of models for cryogenic
temperatures and the requirements to be met by such models were
gathered - with one of the major sources, of course, being"the
people at NASA Langley. One of the main questions concerned the
way in which two model halfs could be joined since any connection
with access through the upper or lower surface was ruled out.
After some pre-tests with bondi~g failed, it was decided to
braze the model components.
Various manufacturing pre-tests lead to a work plan to which the
.sequence of model construction had to adhere. The construction
was accompanied by frequent checks to avoid geometry deviations
beyond repair. After model completion a final check of the
surface contour was carried out on a ZEISS precision gaging
machine at DFVLR Braunschweig. The only manufacturing process not
carried out at DFVLR was the brazing which was done, after
expert counsel by DEGUSSA concerning the silver solder to be
used, by DANNER Schutzgastechnik und Apparatebau GmbH. who
specialize in brazing under protective atmosphere.
2.1 MODEL DESIGN
\ '
Model design features and pre-tests are summarized in
following viewgraphs.
2
3span
chord length
thickness
•
•
MODEL DESIGN REOUIREMENTS
I, A total of 90 pressure orifices distributed in two chordwise
and one spanwise row,
2, Pressure orifices must be drilled into the surfaceJ i,e'J
the pressure tubes must not come to the surface,
Hole diameter 0.3 mm (0.012 inch).
3, Channels for pressure tubes must be as narrow (hei0ht and
width) as possible to ~et maximum bending resistance.
4. Establish coordinates of all drill holes in order to be
able to drill pressure orifices into the surface.
5. Provide for special orifices in the nose and trailing edge,
Orifices should not influence each other,
6. Locate the soldering plane near the neutral bendin0 zone
so that there is essentially no shear stress in the
solderin9 layer.
7, Main dimensions of the air-foil-model,
202,69 (8 in)
151,40 (6.0)
18,61 (0.73) (10-2) 12 %
20,49 (0,80) (R4) 13,5 %.
8, Desi0n must meet soldering requirements) i.e.) allow for
solderin0 gapsJ solder deposits) ~as-channels) flow
direction of the solder,
9. No screw connections.
CHOICE OF MATERIAL
I. Stainless steel,
2, No embrittlin~ and loss of tou~hness at cryo~enic
temperatures.
3. Little or no warpinr,
4, Good wettability with silver solder.
5, Surface able to be burnished and polished at the
buff wheel,
6, No embrlttllnp after solderlnQ-heat-treatment,
7, Safty factor aQainst 0,2 %yieldJ 3 or more; safety factor
aralnst ultimate 4 or more.
4
MODEL MATERIAL PROPERTIES
Note: Same silver solder was used for soldering pressure tubes
inside model and brazing model halfes.
5
I. Material selected
St 1.4301 J AISI Type 304 J SAE 30 304
1.6900 (type for cryogenic use)
85 J
12 kpm/cm2
8 kpm/cm2
1053 K
1393 K
0,28 %
80 K
at 78° K
Working temperature
Temperature used
Degussa 7200 DIN 8513 L-Ag 72 J 2.5151,ASM-ASTM BAg-8.
Ag = 72 %
Cu = 28 %.
Cr = 18 %typical
N = 9 %typical
C = 0.07 %max,
Si = 1.0 %max,
~1a = 2. 0 % max.
3. Physical property
Thermal expansion
between 293 and
4. Silver solder:
2, Mechanical properties at ambient temperatures
0,2 %yield strength minimum 185 N/mm2
at 78 K ~ 300 N/mm2
ultimate strength minimum 500-700 N/mm2
at 78 K ~ 1180 N/mm2
Impact:
DV~1-sample
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fG'1?tJ/ of f:l6e ch4reel /h
.,t,e fA f(,e
0,2..
PrepQfoflOn of f(,e -hlhe Illfels n, ~ S,'(vt'r:..
!lJltle,@d fo f{,t2 ,,,,,,/de of ft,e Inode (, {..,t*Jt{.s
welded 0 til a. tJ,@rr.rfo ~(;&tt/Jte fAJetd,i.1fj matt,/I1ft.
Alf f!, 01"(/ l.J~ hat- eh 0Y9 t,
thfCKneJ'f,
For .{/oocL J'old~r(tlg.
Re~t.1"l"e".S let! .Io ideP'".
1
For /i'leJrYfJ4V- (Jrt)() V@S ..
~
R€f/k/t·f2.S {.e.fJ ~;e(I4.
For .,t{,i~l pro f/t es. GrfJovt'$
on boHr he!.f..! 1hfJf4ld fit
-to geft,er.
Keept muct. s'-{v@r ~ret&f{)r ih ft,e
c.Ofl?~r£, LtU! f)fJod- ..
.. :~ .. ' .... ,.... ~ .',... ' . '.... ~ .. :.. .. ',....."'........ ... . . ~ ... ·.,_.
orifices in CAST 10-1.. I R $'
StQnc(Qrd. prerfUre OYtfice
0,:'
•Orl·1~,'ces Ih tl ftn4{(@r' modeL of C/fIT ItJ,.2.
prese ttl -(i!1 fA en ele r CC7'b't.r{yW C ]!..;O (;J..,
G~q3 I
~~!{
y;
L~
... @
. ~j
I
°A:r
(j) If model ft,fCkn(J~ is nat;-
SlAff,-(,t'~h t
o If fl"e ori{ic<a is loccrted.
'Where Me yfube is 7'i1 ick'er
~ Q 111 ftt IE a it" fa /1-. .
The. (Ube is rect'fceti /1'1 dlamefer
by f"ndlt&:g i't t4voMJ4 a oIra~
die.
'-,\I( '.) ~.i'j.'"
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2.2 MODEL CONSTRUCTION
Work plan:
I. Model upper and lower half pre-milled to rectangular blocks,
2, Approximation of the air-foil contour by stepwise milling.
3, Heat treatment of model halfs at brazing temperature
(1120· c)J to avoid warpage during later manufacturing
processes.
4. Milling and electrical discharging of the channels for the
pressure tubes.
5, Drilling of the sockets for the .pressure tubes, Positioning
and fixing-in-place of the tubes,
6, Silver soldering of the tubes and filling of the solder
deposits for the surface brazing in activ and protectiv
HJ Natmosphere.
7, Check of model dimensionsJ cleaning of the surfacesJ
fitting and clamping of the model halfs.
8. Brazing in activ and protectiv gas. Final check for
possible model deformation.
9. Cyclic cooling to LN2-temperatures.
10. Contouring of the model by NC-millinQ. Hand finishing of
the surface, Drilling of the pressure orifices.
II. Final check of the air-foil contour.
Certain stages in the manufacturing process are shown in the
following viewgraphs,
13
HEAT TREATMENT AT 1393 K (1120· C)
I, Both models halfs
After initial millin0 work heat treatment in an H-activ
0as for stress relief before millin9 model interior,
Cooling durinr 0,5 hours in the furnace coolin~ zone
to about 300 0 C,
2. Silver solderin~ of the tubes to the inner sockets.
Coolinr during 0.5 hours in the furnace cooling zone
to about 30G O C.
3. Brazing of upper and lower model parts.
After the first attempt to braze the model CAST 10-2)
an unaccePtable barrelinr of the two parts was observed,
In a second attempt the model was wei0hted down a~ainst
a solid steel plate during the brazin0 prozess.
For the model R4 a specially desi~ned clampin~ device
was used.
14
upper surfaces
Pre-milled parts before first heat
treatment to get the model
stress free
15
View of the model,. inside with
pocket and tube channels
(upper part)
View of the model inside
(lower part)
16
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.) ') ','\' .
. \( '\ '\
ll-essu t'e ~e
After silver soldering of the tubes
18
Soldering
Location of the solder deposits on
the pressure side half,
The deposed silver solder can flow
in to the plane gap between the
model halfs
19
Set up for drilling the pressure
orifices with a spezial drilling
device
20
21
=80 %)
Good orifice
Orifice freed of broken drill tip
by electric discharge
if ~:.:.:..
-:1'.
Quality of pressure orifices
No effects on the pressure readings
were observed.
Orifice drilled by
electric discharge
Drill not centered
.-
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& &
lJ &
rl
0'\ 'tn'V'/\~J1U I
:.;;-\({~.~/~'~-====~--------10
-10
.,-.G!--t--+-+----1I-----~-
CAST IO-~/DOA~
L c 15Z.J4 mm (kryo- nD/ell )
Sc/I- ktJnlur
Ab tAle/ch u nr \f011
~deJ- 50/(- ko~;'!/..r X C;O
-eo
20.0
HASSE TN l
2>e VIa..t,;, .,~ deJ''IZ1 eJd),1tn.{'
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PERMANENT MODEL GEOMETRY CHANGES DURING THE CRYO-TESTS
- No spanwise warpage
- No change in plan view dimensions
- No change in surface quality
- No leaking or stopped up tubes
- No. gaps between brazed surface
- Model thickness changed by + 0,03 mm <dmax = 18.24 mm)
23
•TIME USED FOR MODEL COMPLETION
1. Model construction 5 - 6 month
2. Man-hours for two models
%
2.1 Design J development 1180 24
2.2 Documentation and
NC-programming 290 4
2,3 Construction 3300 67
2,4 Quality checks 250 5
Total 4920 100
24
25
3. SOME AERODYNAMIC RESULTS
creasing Reynolds number.
are a result of the boundary layer being laminar down
surface shock. The drop in (CL/CD) . M in thatmax =
to the transition point moving upstream with in-
number range
to the upper
range is due
Some deviations between TCT and CFWT results were observed in
the d~ve~opm~~tof separation with ~ncreasing angle of attack.
They are most likely due to side wall effects which are more
pronouric~d i~ the case of the TCT where the aspect ratio is
h/~'= 'i.jj' ai 'cci~pared to b/ci = 3 f6r the CFWT. in ord~r to
Figure 3.2 compares results obtained in the 0.3-M TCT with data
from the Lockheed Georgia Company Compressible Flow Wind Tunnel
(CFWT) and, in the lower Reynolds number range, from the 1 x 1
Meter Transonic Wind Tunnel G6ttingen (TKG). Qualitative and
qantitative agreement between all three tunnels around Re = 4X10 6
and between TCT and CFWT in the Reynolds number range covered by
. .
these tunnels is quite good. Especially remarkable is the agree-
ment in the case of free transition between Re = 4x10 6 and
Re =' 1Ox1 0 6 where the flow development is essentially determined
by ,the movement of the transition point.' Note, that· the stagnation
conditions for the TCT and CFWT are, especially at the higher
Reynolds numbers, quite different: They are at Re = 30x10 6 for
the TCT TO = 115 K and PO = 4 bar, for the CFWT TO = 287 K and
Po = 11.9 bar.
In Figure 3.1 the Reynolds number dependence of the aerodynamic
parameter in Breguet's range equation is shown for two Mach
numbers and fixed and free transition. There exists a strong
ReYI~dS number dependence up to the hi9hest Reynolds number
investigated with a clear indication that an extrapolation to
higher Re-values on the basis of the existing data is not possible.
The high values in the aerodynamic parameter in the lower Reynolds
to [1].
In this paper emphasis is placed on model design and construction,
however, it is thought of interest to briefly point out some
aerodynamlb 'results' obtairied with the airfoil'DAST '1D-2/DOA2 in
~ the TCT tests. For details on the airfoil the reader is referred
better understand side wall effects tests with a smaller model
of the airfoil CAST 10-2/00A2 are scheduled in the TCT.
[3] BAERLECKEN, E. Merkblatt Stahl 470. Stahle flir tiefe
et. ale Temperaturen
~.'.. \ 1 .
; "
Development and Wind Tunnel Tests of
Three Supercritical Airfoils for Transport
Aircraft.
Zeitschrift flir Flugwissenschaften 23,
Heft 7/,8, 1975
' .. '
Werkstoffblatt 630 RB
Ausgabe: November 1974.
Nichtrostende austenitische unstabilisierte
CrNi-Stahle-vom Typ 18/9
Model design and instrumentation
experience with continuous-flow cryogenic
,-
tunnels.
26 i
"'> ( >•• > - -,
".' ,.-, ,'.'.1
'.' , . " ~ ,
,--
':: .. ' ..... "'-" .. , .-',
[1] STANEWSKY, E.
ZIMMER, H.
[2] KILGORE, R.A.
[4]
5. REFERENCES
4. CONCLUDING REMARKS
.' '.' ',:',' . ',.. !. ~ 1 . t .~ ~:
As part of a NASA/DFVLR cooperative program two transonic airfoils
- were tested in the NASA Langley 0.3-M TCT. Model design and
construction was carried out by DFVLR. The models designed and
constructed as described in the preceding sections performed
ext~ely well under cryogenic conditions. Essentially no per-
manent changes in surface quality and geometric dimensions occured
during the tests. The aerodynamic results from the TCT tests
which demonstrate the large sensitivity of the airfoil CAST 10-2/
DOA2 to Reynolds number changes compared well with results from
other facilities at ambient temperatures.
[6].'.,TOBLER,~.R.L..) Mater'ials' for Cryo'genic
Wind Tunnel Testing
NB SiR 79-1624
Werkstoff-Tabellen der Metalle,
Stuttgart 1972.
LHB 88501 (NASA)
User-Furnished Wind-Tunnel Model Criteria
. .'
.. : "f
t ~ , 1o,
,;
.•-/
27
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, 1'.;'1 '.4'" ~. ;,;;,. • ..; ~ 'J J,.
..','
~! '".' ..... "., ; ~ ", , .•.
',., .... '.
, " :.; " I ~ ~. II '1 • t ,.' ,J '-:,.
[7] WELLINGER-
GRIMMEL-
BODENSTEIN
~
[5 ]
..
"
•
..
•
5'"
Re
. <, .
. "
5
0 .. -:,..'. 'i.,,,
Figure 3.2: Reynolds number dependence of lift as determined
in various wind tunnels. M = 0.765 a = 20
00
.•~O- ~~r--n...,~ Free Transition
~ V V
pK A ,ivA,.~~ /"4
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/'[J/
./
/
V
I.....
~ I'-..
V ......
CJ.~/ /, ~ Transition fixed in 7% c
/'
,..,,)
;' ~~
",-
aVo
0 TKG
t:::. CFWT
0 0.3 -MTCT
~ } . .. ~ 0, , ~ . ~ . ,• -~ ): ~ • J, '>, ., '''' •. , .l' , , : ~ ... ' , , ~1-
" ,,' '" " " ..... Airfoi'l CAST 10-2/DOA2
0.70
0.60
0.65
0.55
0.50
.~ ,
, ...
,- 3 1176 00520 9714 i
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Design and construction of 2 transonic airfoil models for tests in the NASA Langley C.3-M TCT

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