Laminar flow of liquid coolants in rocket engine

Ayvazian, R. A.

English

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The following information is provided: 
U. S. Patent  No. 
Government o r  
Corporate Employee 
.: * 3;534,555 
North American Aviation, Inc. 
Rocketdyne Division 
: canoqa Park, ~ a l i * n i a  91304 
Supplementary Corporate 
Source (if  applicable)  
NASA Patent  Case No. 
NOTE - I f  this patent  covers an invention made by a corporate 
employee of a NASA Contractor, the  following is applicable: 
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Copy of Patent  a i t e d  above 
https://ntrs.nasa.gov/search.jsp?R=19710008156 2020-03-17T02:46:02+00:00Z
Oct. 28, 1970 JAMES E. WEBB 3,534,555 
ADMlNISTRATOR OF THE NATlOFdAL AERONAUTICS 
AND S P A C E  ADMiNISTRATIQN 
LAMINAR FLOW ENHANCEMENT 
Filed March 6 ,  1368 . 
INVENTOR. 
RALPH A. AYVAZIAN 
United Srai-es Patent 06 3,534,555 ce Pate~ ted  0.h 2% 1970 
1 2 
Still anotlle~ object of t11i.i invention is to plovide a 
3,534,555 nlctbod for eiihancing the laminar flow of fluids. 
AR m O W  ENHANCE-NT 
James E. Webb, Adiministrato~ of the Na~orclal Aeronau- SUMMARY OF THE INVENTION 
tics and Space Adn~ilinis&atiom, with respect to an inven- 
tion of Ralph A. Ayvaaian, Canoga Park, Calif. The above and other objects is accomplished by the 
Filied Mar. 6, 1968, Ser. No. 710,949 utilization of a surface active agent, also known as a 
Ent. el. FO2k 9/00; F17d 1 /16; ROlf 17/42 surfactant, compatible with the chosen liquid to coat the 
U.S. Cl. 60-217 10 el&lns walls of the vessel or conduit which the primary liquid 
is to contact. The term surfactant refers to any material 
that will reduce the surface tension between the primary 
ABSTRACT OF THE DPSCLOSURE liquid and the walls which it will contact. For example, in 
A method of improving the laminar flow of liquid a film cooling application the walls of the rocket chamber 
coolants in rocket engines comprising reducing the can be precoated with a surfactant material, preferably 
flow frictioll losses through adding a surface active agent in a paste form prior to the injection of the fuel against for the liquid either directly to the liquid or by coating 15 the wall. Alternatively the surfactant agent can be sprayed 
the walls of the chamber with the agent. onto the walls from a separate source simultaneously 
with the fuel or oremixed with the fuel. When the fuel 
is waer miscible,-then materials such as glycerine in a 
water solution can serve as a good surfactant to assure 
ORIGIN OF INVENTION 2n a film of the fuel on the walls. In a closed container such 
-" 
as recirculating tubes about a rocket chamber, the addi- The invention described herein was made in the per- tion of a small amount of surfactant such as polyisobutyl- formance of work under a NASA contract and is subject ene in parts per million will reduce the wall friction. This to the provisions of Section 305 of the National Aero- 
of course enables a greater amount of fluid to pass 
nautics and Space Act of 1958, Public Law 85-568 (72 25 through the lines at flow. Stat. 435; 42 USC 2457). It is believed that the invention will be better under- 
BACKGROUND OF THE INVENTION stood from the following detailed description and draw- 
ings in which: 
Field of the invention FIG. 1 is a cross-sectional view of a rocket engine 
30 utilizing film cooling of the inner walls; This invention is in the field of fluid flow and more FIG. is a cross-sectional view of a rocket engine hav- particularly the invention pertains to a method for im- ing cooling passages in the walls thereof. proving the laminar flow of fluids in contact with wall Turning now to FIG. there is seen a rocket engine 
structures. 11 having a solid wall thrust chamber 13 which can be Description of the prior art 35 of a suitable material such as an ablative composition 
One of the known approaches for cooling rocket thrust Or refraclory metal. A nozzle portion 15 is formed at the 
chambers is known as filming cooling. In a typical appli- rear of the thrust chamber while the injector 17 is affixed 
cation of film cooling, a portion of the injected fuel is di- to the forward end. In this type of a rocket chamber no 
rected against the inner walls of the thrust chamber form- means is provided to internally  COO^ the walls 13 of the 
ing a thin film thereon while in other applications, water 40 chamber. AS a result film cooling is utilized. The liquid 
or other coolant is separately sprayed against the walls of oxidizer is directed throngh a central inlet line 18 to a 
the chamber to provide such a coating. The thin films manifold 19. The liquid oxidizer then is directed out- 
protect the chamber walls from burn out. To  date there wardly from orifices 21 in a typically circular Pattern. 
have been several problems with regdrd to achieving sue- The fuel is admitted to the injector through a line 23 
cessful film cooling. The main problem resides in the 45 and fills a concentric manifold 25 above the manifold 19 
inability to obtain an even, uniform film that is continu- for the oxidizer. The fuel is then directed outwardly 
ous along the walls of the &amber. The normal tendency through a first set of ~ 0 n ~ e n t r i ~  or fices 27 SO as to inter- , 
is for the film to streak the walls providing an uneven sect the oxidizer stream and mix therewith. Additionally, 
coating thus not achieve the desired end results, It the fuel is further directed Out through a second set 
is recognized that the quality of the heat transfer through 50 of orifices 29 which are angularly disposed so as to force 
the fluid depends on the laminar boundary layer of the the fuel against the inner walls 31 of the chamber to form 
fluid on the wall which is to be cooled. It is particularly a coolant film thfxeon. 
due to this inability to achieve a good laminar boundary In the course of the travel of the fuel along the inner 
layer that the prior art often fails. walls 31 of the chamber the fuel will absorb heat while 
Another means for cooling rocket chambers is to pass 55 vaporizing and eventaally will be burned off. The absorp- 
the coolant, which once again can be the fuel itself in tion of heat by the fuel will serve i0 act as a coolant to 
the regenerative situations or a disposable fluid such as protect the waiis, TO date, this aforedescribed procedure 
Tvater, through passages provided in the avails of the has been the ~lormai approach to film cooling. Both the 
chamber. Here most of the problems are in achieving a oxidizer and fuel are punip?d into a thrust chamber at  
sufficient flowrate of fuel or the flowing of coolant through 60 e~iremely high pressures with resulting high velocities 
the passageways at faminar conditions, The size of the wnen pa5sin:r througl-i their injector- orifices into the 
passageways are limited by weight coilsider.atioi?s chamber pni.tion. At these hi& ve!oi.iii?s the fu-I has a 
packaging. Th~ls  within the liii?iis of the rocket engine tendency to separaie from the wall anci st]-eak co as to 
design it is desirable to achieve a. greater fiov~ of coolant prevent n srrlficient :;oolanl fiEi11. '1 hu; it is impetaiive when 
yet maintain, as indicated, laminar flow conditions. 65 the fuels are us?<! to cool the wa?!s that 30 strea!:ing or 
Thus, it is an object of this invention to provide a sc-r!aration take pliice. In order to accomplish this a 
method for improving the film cooling of surfaces. third inlet line 33 directs a suifaclani composition rhrough 
A further object of this invention is to provide a a col~cenlric manifold 35 formed about the oxidizer mani- 
method for improving the flow of fluids in closed pas- fold 25 in the injector. The surfactant solution then 
sages. 70  passes out through orifices 37 and is directed against the 
Still another object of this invention is to provide a inner x.valls 3% of the chamber. If the conventional fuel is 
method for reducing friction losses of Ruids over su~faces. hydlazine, for example, a surface active agent that is 
6 )  r'3 f - - 
e>,3c>iib; i , r> 
3 4 
rn~s~tblc  \ \ i l l 1  w'it~i t'ii b~ ~!li,-c? alnc, lt,:,,iih2~e it\eii  ti iilibtl ihio ail t ~ I L  'riie 57 An ,,lje~tol 59 I., $10 
1% compatlbic vir~h \\,.tel f l r u i  c i a 4  rnaip1lal iii lilair~fold \,i,teJ 11h inlet 61 C I ~ I L L ~ ~ ~ I S  L ~ L  f~iel  to a ceiitcr manr- 
35 could conpirse foi erarilpie plyet i~lye~le oirde a> a told 63 and ilrei-i outwaidiy ihrou"~ oirhces 65 A s~cond  
s~lrPnct,iflt in awatei S O ~ U L ~ O I I  Thc s~iliactani sobition niay inltt 67 clirccts the  oxidize^ ~'L111zed LO a second corl- 
be riljecied oiily i t  i:i- i~iltidl s l d ~ t  t ) f  he errg~fic a d  t el l l i ,~  oia~i~foiil 69 and  ouiwaidly thloiig:~ oilficea 71. 
to en,lb?e tbz fuel lo 1n1tialFy lay dovn up011 thr lrlwr 7 h~ ,ype of englne show111 In FIG 2 may nblize the cool- 
walls 51 of ihe cham be^ in a I even non-stieahllly film. ,int fol that p~irpose only. However many rocket englnes 
Alternatively, the solution can be coiltinuaily rnjecied lo- are cirsig~ied utillzing what is leimed regenerative cool~ng 
geihei with the fuel. The an:ount of the surfactant soh-  wherein the fuel 1s dlltcted through the passageways 
t ~ o n  will not be too great since only approximately 10 to ?long the length of the chamber pilor to bung ~njected 
100 parts pel million of the suriactant to fuel oi coolant for Liltin~ng Th-, fuel exiting at 57 would thus be di- 
is required 111 ordei to achleve the results of this inven- iecle-t to en te~  tlie chambe1 at inlet 61. The temperature 
tion and assuie a film occurring. The paiticular airange- of a fuel is thus substantially raised piior to the injection 
incnt shown In this fignle prevents the iuel utilized Eor illto the combustion chamber. The plnicipal of thls lnven- 
combustion pulposes, namely that commng through oiifices 15 tlon can once agaln be used in order to achieve h~gher flow 
27 from being aifected by the addition of a surface active lates 19 the legene~atrve cooling passages upon adding a 
agent. Thus, the impulse performance of the locket en- compatible suifactant agent to the materials providing the 
gine is not affected. However, most of the surfactants, overall perfoimance of the englne is not affected. As ple- 
particularly in the extremely small amounts requiied, will v~ously indicated, the small amount of surfaclailt re- 
not affect the pe~foimance of the rochet engine. Thus In 20 quned vv~ll not affect, in inost insta~ices, the perfoimance 
these instances the sepal ate line 33 would not be iequl~ed of the engine. 
and the surfactant can be premixed in the small quantities As was pointed out, the mechanism involved in this 
required with the fuel itself. invention through the addition of the surface agent is not 
It is to be understood that the amount of surfactant wcll established However, it is believed that the shear 
requiied will vaiy as to the material utilized and can be 25 ctiess at the wails is lecl~rced coinpaied to solutions with- 
determined from ielatively straight fo~vvaid ioutine ex- out the surface act~ve addltive It is hypothesized that the 
pelinlentat~on to detein~ine the amount needed Genbr- addittve caiires inoleculai alignment at the wall in the 
ally, the amount of a surfacrant \vi11 be within the aiea sheai dllect~oil and thus in tuin the overall f~iction of the 
of paIts per million of the fuel used As rtldtcated, hy- ~esistai~ce of :lie wall to the rnovement of the fluid pas- 
diazine, a very popular fucl, 1s m~sclble with water and 30 sage is lil e ~ i s e  leduced. 
thus a su~factant that is mlsclble with \vatel would be In addition to the afoiementioned surfactants, typical 
utilized. Foi a hyd~ocarbon fuel, a surfa~iailt such as examples of water soluble agents include sodium alkyl- 
polyisobutylene can be used in a calriei such as b:nzene. naphthalene sulfonaie, polyethylene glycol lauryl ethel, 
Once again the appioach to deieimine the amount of sodiunl fauryl sulfate, sodium decyl benzene sulfonate and 
surfactant necessaly to achieve the results of this inken- 35 the like Most of these suifactants can be cornblned with 
tion can be ach~eved through experimentation by slowly a suitable piotein matelial such as a gelatin to form a 
ra~sing the slight amount of surfactant brought into line paste suitable for applying a p ~ i o r  coating to the sur- 
53 to the po~nt  where stieaking and spottlng of the film faces. When a paste coating is used, it should be apparent 
of fuel is eliminated. that the embodiments shown in the figures would not be 
Turning to FIG. 2 there is seen the utilization of this 40 requi~ed to bling the agent into the walled structmes. 
invention in a rocket chai~lber whereln the walls of the Obviously, the paste coating is particularly applicable 
chamber are provided with coolant passages. 'When a during short duration filings, since it degrades rapidly 
suifactant is added the fuel flow fliction losses are re- under operating conditions. Howevel, the paste is also 
duced and increased flow rates ale possible for a given applicable to longer duration runs where it is particularly 
available pressure. This can be explained by the follow- 45 desired to provide a surface where the film can start even- 
ing equations for circular ducts where fluid flow AP is ly without streaking. Once a good film has started, its 
given by the following equation: maintenance is more easily achieved. Further, some sur- 
L v2 factants such as glycerine can be coated on a surface A P = 4 f  -  
D 2 ?zc without foriaing a paste therefrom. 
50 Most surfactants pelform better when diluted in a suit- 
where: able solvent theiefor. Thus, as indicated in the aforegoing 
f=wall fliction factor description, the surfactant is first diluted in a solvent piior 
lP=p~essure drop, l b ~ . / f t . ~  to use in accord with the herein invention. This dilution 
L=line length, ft. IS generally plefeiable whether the surfactant is injected 
D=line diametel, ft. 5 j separately as shown in FIG. 1 or is mixed with a coolant 
V=fluid velocity, ft./sec. as in FIG. 2. Of course, when the coolant is a suitable 
g?=gravitational constant, ft   be^.^ solvent, such as water, then the surfactant is added di- 
p=fluid density Ibs /fL2 ~ect ly thereto Further, it is contemplate~l that a surfactant 
~ h ~ ? ,  when for example, 10 paits per lllili~on of p l y -  can be added directly to a fuel or other coolant ~ i t h o u t  
ethylene ls added to a water coolant, the wail frlc- co prEV:ous dllut~on if the siirfacfanl will pelfolm satis- 
tion fact01 is ieduced alld the ove~all system plessure dtop factorily under t h ~ s  condit~on. 
17 reduced EXAMPLE 
As seen in FIG 2, a rocbct engine 41 is comprised of 
an outer slrell 43 znd tile innei shz l l  $"s~avlng a coolarlt To denlon~trak the eFeclrveness of the herem rnven- 
paiczge oi pdssage5 d.7 tireiebeiv een 7l.c rnner shell 45 t l c 3 1  a roclet eng~*lc lor feiti,~g nn rrr i -ctos destgn IS con- 
1s folrned \vii?r a nozzle 49 with a fi Eter h l o ~ ? <  50 betw~en sir ilctcd rrslng p1a.n stezl mzI1 const~nct~on for t he  cham- 
rt and the oilier shell 41 iin this regron The ~oolarit pas k. r poition 111,s coi*struciioi: saves consideraLle cost fol 
sage 47 can corlip i,e a singular annrfai jacltei as s t i o v ~ ~ ~ ,  sv(h tD-t p r ~ ~ ~ d ~ ~ r e "  Thp ~ v a l l ~  of thz eh7mher  PI^ cooled 
ol a plurality of rndlv~dual lubes cariying the coolant b) providing zi separate nianrfold surroundiilg the ~ajector 
from a lear manifold 51 at  the rear end thereof. The '70 lor dampi~y  vater lnlo tne chaiilbei to forin a film on the 
coolant is d~rected through lrne 53 to the lear manifold wall? tflereof A 250,000-pounrl thrust engne rising 11q1lid 
51 v~hlle the addtive may inier5ect the coolant line 53 oxystn arrd qaseous hydlogen can be fired foi abont only 
through a separate Itne 55 to mru with the coolantppi~nr o~ ih~id  of a :ern-~ci befoie burnout oC the ch,tmher 
to enterlng the chamber In this configuration the coolant The waiel is fed ;n at the rate of 200 to 500 pounds per 
will pass along the entiie ~valls in passage 4'7 leaving the i j  second In such icjector tests, rt is desirsble to achleve 
3J *534 . 5 [ j b  
5 6 
run.; of at leiist one secon,l. .;"‘!lus when th; steel v,7all:; and :;topping the tiow ai' s:iiii siiri;ice activc ;:gent after 
of the test chamber are previoiisly coated with glycerine, a coating has been clepositecl on said walls stiflicici~t o 
the water adheres as a film thereto. Runs of one second reduce said frictional resistance. 
duration then are achievable. 7. The method of claim 1 wherein said surface active 
\rVh.at is claimed is: agent is polyethylene oxide. 
I. A method of cooling the walls of a liquid rocket 8. The method of claim 7 wherein said polyethylene 
engine chamber comprising: oxide is in a water solution. 
directing a liquid to said engine, 9. The nmethod of claim 3 wherein the amount of sur- 
directing said liquid along the walls of said chamber, face active agent is from 10 to 100 parts per r~million 
providing a surface active agent for the liquid upon parts of fuel. 
said walls in an amount sufficient to reduce frictional 10. The method of claim 3 wherein said fuel is hy- 
resistance of said walls to said liquid, said surface drazine and said surface active agent is polyethylene 
active agent being fully miscible in said liquid. oxide. 
2. The method of claim 1 comprising: References Cited 
mixing said liquid with said surface active agent prior 
to said liquid entering said chamber. 
3. The method of claim 1 wherein said liquid is the 
fuel for said engine conlprising: 
injecting a portion of said fuel against the inner walls 
of said chamber to provide a film thereon. 
4. The method of claim 3 additionally comprising: 
separately injecting said surface active agent against 
the walls of said chamber together with said fuel. 
5. The method of claim 3 comprising: 
coating the inner walls of said rocket chamber with 
said surface agent prior to injecting said fuel. 
6 .  The method of claim 4 compiising: 
directing said surface active agent against said walls 
concurrent with the start of said engine, 
UNITED STATES PATENTS 
2,821,205 1/1958 Chilton -------------- 
3,169,368 2/1965 Munding ------------ 
3,215,154 11/1965 White -------------- 
3,307,567 3/1967 Gogarty ------------- 
3,352,109 11/1967 Lissant ------------- 
3,373,107 3/1968 Rice ---------------- 
DOUGLAS HART, Primary Exanliner 
U.S. C1. X.R. 
60-204,258,260; 137-13; 165-1;252-352 


Laminar flow enhancement Patent

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