OVERVIEW OF THE SCRAMJET COMBUSTION CHAMBER LENGTH

Transcription

1 ISSN nd Intnational Congss o Mcanical Engining (COBEM 0) Novmb -7, 0, Ribião Pto, SP, Bazil Copyigt 0 by ABCM OVERVIEW OF HE SCRAMJE COMBUSION CHAMBER LENGH Buno Fia Poto Paulo Gilbto d Paula oo Instituto d Estudos Avançados (IEAv) - vo Coonl Aviado José Albto Albano do Amaant, no, Putim,.8-00 bunopoto@iav.cta.b too@iav.cta.b Abstact. Scamjt is an aibating aonautical ngin tat uss t obliqu/conical sock wavs gnatd duing t ypsonic ligt, to pomot compssion and dclation o stam atmospic ai at t inlt o t scamjt. On t most impotant and citical componnt o t scamjt is t combustion camb. Pysical and cmical aspcts limit t lngt o t combusto to a minimum w t ai and ul must av noug tim to, to act and to las t at to t supsonic ailow. is pap intnds to ovviw som o t availabl litatu o a simpl, ist appoac, quations tat can pdict t minimal allowabl lngt o a scamjt combustion camb. Kywods: combustion camb, ypsonic aospac vicl, scamjt, ypsonic aibating populsion. INRODUCION In od to duc t costs to spac accss it is ncssay to aciv nw and mo icint ways to ac obit. On o t most pomising tcnologis is aibating ypsonic populsion, spciically supsonic combustion amjts also known as scamjts. a sval callngs in t dvlopmnts o suc ngins. Du to t supsonic natu o t acto t is a minut amount o tim o t sval pysical and cmical pocsss to occu. Most o ts pocsss can b studid on ypsonic gound tst acilitis and in od to xpimnt scamjt ngins using ts acilitis is ncssay to wok wit ducd siz modls. a pysical limitations o t minimal lngt o suc ngins to guaant a pop ul to ai ing, complt combustion action and at las to occu. is pap is an ovviw o sval ncs tat mntion t lngt and basic combusto gomty calculation and pdiction o scamjt ngins.. REACOR GEOMERY scamjt acto, at t compssion stag, can b dscibd wit ou componnts: t isolato, injcto block, constant aa combustion camb and divgnt combustion camb as sown at Figu. is pap consids a simpl sction aa wit ctangula sap, ignoing any cts causd by t sap cons o t duct.. Isolato Figu. Camb lngt gomty. isolato is a duct tat in gnal plays no ol ot tan potcting t inlt low om advs back pssu (Sgal, 009). isolato also compsss t low as a sult o wak obliqu sock wavs gnatd by t spaatd low at t walls (His and Patt, 994) as sown at Figu. 747

2 ISSN B. F. Poto and P. G. d P. oo Ovviw o t scamjt combustion camb lngt Figu. Sock tain gnatd by t spatd low insid a constant aa duct. (His and Patt,994). His and Patt (994) suggst an mpiical lation btwn t ntanc Mac numb, M, pssu atio, p / p, lngt, L, igt, H, bounday lay momntum ticknss, q, and t inlt Rynolds numb, R q. L H 4 q H R q é ê êë æ p ö æ p ö 50 ç ç - è p ø è p ø M - ù ú úû () Mac numb at t xit o isolato is givn by (His and Patt, 994): M é g ù ê æ - ö g M ç + M ú ê g -ú è ø ê - ú ê æ p ö + g M - ú ê ç p ú ë è ø û - () conind aa by t spaatd low can b dtmind om consvation o momntum (His and Patt, 994): A é p ù ( + g M )-ú ë û C ê g M p A () Equation is plottd on Figu o an nty Mac numb M and a atio o spciic ats g.4 (His and Patt, 994). Figu. Vaiation o conind low aa action wit imposd back pssu atio, o isolato Mac numb and atio o spciic ats g.4 (His and Patt, 994). Accoding to u and Sgal(00) and Sgal (009) t isolato lngt can b dtmind by: 748

3 ISSN nd Intnational Congss o Mcanical Engining (COBEM 0) Novmb -7, 0, Ribião Pto, SP, Bazil ( -) X g é p - p ù g - + ln + ln p DH 4 K g êë ( - p)( -) - p úû g (4) w: F (5) p A m g & p p ( g -) H0 p A out (7) pin w 4K 44.5 is t constant iction coicint at t duct ntanc. Accoding to u and Sgal (00), Equation 4 was ound to pdict t sock tain lngt accuacy wit 0% ov a boad ang o xpimntal sults, including ducts o vaious saps (ound and ctangula), ntanc Mac numbs anging om.5 to 5, od o magnitud vaiation in t ntanc Rynolds numb, and dint iction coicints. Fo cicula ducts Sgal (009) s to Equation 8 as basd on xpimntal data o a cicula duct. u and Sgal (00) also to tis quation: (6) X D q é R q M - ë ( p ) ( p ) ù û (8). Ful and ai ing, injcto block. ing o ul and ai pocsss a dtmining actos tat lad to at las and tust gnation. main ason o tis caactistic is t millisconds o luid sidnc witin a scamjt acto (Sgal, 009). o, t injcto block dsign and sulting ing lngt is a citical aspct o a scamjt acto dsign. Fo gasous ul injction t a t main mcanisms: paalll injction witin t low, nomal injction om t walls and votx gnato o yp injctos (Sgal, 009; His and Patt, 994)... Paalll injction axial injction uss t sa lay omd by t two paalll stams o ai and ul to t actants, as sown at Figu 4, Figu 4. Scmatic o sa-lay ticknss dvlopmnt (Sgal, 009). axial injction quis long distancs to aciv t molcula ing quid o combustion i compad to t wall, ppndicula typ o injcto (Sgal, 009). His and Patt (994), Sgal (009) and Klic and Mundi (0) us an mpiical solution o t ing lngt. L b C,7 0,79 o (9) L b C -,04, o > (0) 749

4 ISSN B. F. Poto and P. G. d P. oo Ovviw o t scamjt combustion camb lngt w b is t igt o t acto and C is a acto vaying om 5 to 60 o ully tubulnt to a ully lamina sa lay. usual valu is aound C 46 (His and Patt, 994) and C 40 (Klic and Mundi, 0). icincy along t axial distanc is givn by: x x m () x L Muty (000) poposs, o axial injctos in a stp at t wall, tis icincy and lngt lation: m ln( -max) x L - ().. Ppdicula Injction Ppndicula injctos, Figu 5, av sot ing distancs i compad to axial injctos but sults in lag momntum losss (Sgal, 009). Diskin and Notam (987), omioka t al. (006) and Sgal (009) suggst an xpimntal colation btwn t combusto gomty and ul quivalnt atio to calculat t ing icincy at any distanc in t diction o t low om t ul injction position, X ' : x',0+ 0,76 ln () ' x Figu 5. Modl o a tansvs, undxpandd jt in a supsonic aistam Sgal (009). lngt o a complt ing, x', is givn by (omioka t al. 006): x x R 0,79 æ ö,7 ç è R ø (4) His and Patt (994) av a dint mpiical lation: m, 90 ìï x í + ïî Lm ( a) a üï ý ïþ (5) w a is a it paamt wic vais om a 0,7 o widly spacd injctos to a 0, 5 o closly spacd injctos. Lm x is t distanc ndd o complt ing and is givn by Equations and 5. Diskin and Notam (987) suggst t lngt quid o a complt ing ( x l L m ) is: xl 60 G (6) 750

5 ISSN nd Intnational Congss o Mcanical Engining (COBEM 0) Novmb -7, 0, Ribião Pto, SP, Bazil is is valid o sonic ppndicula o paalll injctos om bot walls o a two-dimnsional duct wit t spacing btwn injctos, s, tat is qual to t distanc o t opposit walls, G, and wit injctos diamt o: s d (7) 5 Fo injctos wit an angl His and Patt (994) and Sgal (009) suggst t lina intpolation btwn paalll and tansvs injcto sults... Votx gnato injcto yp o votx gnato injctos av sis o small amp stuctus, livd o xposd as sown at Figu 6 and Figu 7, wit injctos tat gnat an obliqu sockwav ov it. is cats a pssu atio btwn t low ov t amps and t low bsids tm, inducing t omation o votxs tat incas t icincy. Figu 6. Gomty o wall-mountd, unswpt amp ul injctos. (a) Raisd amp. (b) Rlivd o xposd amp. Sid lvation: viw is along z axis. End lvation: viw is upstam, along x axis (His and Patt, 994). Figu 7. Pspctiv viw o swpt and unswpt amp ul injctos (His and Patt, 994). icincy o an axial votx ing wit aisd amps o 0º and injctos wit 0º is givn by (His and Patt, 994): m, AV A x Mix x - A (8) w A.77 o unswpt and A.4 o swpt typ injctos and Lm x is givn by Equations 09 and 0. His and Patt (994) also suggst A4.9 o ig stam Mac numb. Andson t al. (990) sow an mpiic lation o gasous ydogn injction o votx gnato injctos: ing æ x -0.67ö ç q d è ø 0.49 (9) w q is t atio o dynamic pssu o t injcto and t main low wit suggstd valus o 0.5, and.5, and d is t diamt o t injctos. 75

6 ISSN B. F. Poto and P. G. d P. oo Ovviw o t scamjt combustion camb lngt. Combustion camb A constant aa combustion camb can lad to a quick pssu ais, wic is vy diicult to contol and can lad t inlt to unstat (Sgal, 009). o avoid tis ct on can us a divgnt combustion camb to kp t pssu constant duing t combustion pocss along t low, compnsating t at las ct (His and Patt, 994). Diskin and Mundi (987) ound tat t combination o a sction wit constant aa ollowd by a sction wit divgnt low pat can lad to a btt ing and lam olding caactistics, impoving t ovall icincy. Diskin and Mundi (987) suggst t lngt o. tims t al igt i t camb. His and Patt (994) popos tat a al angl btwn 4º and 5º to t divging pat. o dsign t combustion camb lngt on must consid t lngt ndd to t ul and ai, tn t lngt to allow noug tim o ignition and action o t ul ai tu. Essntially t combusto lngt, om t point o ul injction to t nd o t combustion pocss, is t sum o t ndd lngts o ing, ignition and action. Figu 8 sows t tim scal in cmically lows. Figu 8. im scals in cmically acting lows (Sgal, 009). At t ist potion o ai and ul is d at lammabl popotions t is an ignition dlay to t stat o t action. Wn t combustion is alady statd t is a tim o t action to occu and las t ngy to t low. On can say tat t lam taks plac btwn t distanc ndd o t ignition dlay at t injcto block until t sum o t ing lngt wit t ignition dlay and action lngts. Paull and Stalk (990) popos tat tim quid o 95% o t combustion to occu is t sum o t ignition dlay tim wit t action tim, givn by: t i (0) P t -., (),7 P w P is t pssu in atmosps and is t tmpatu in Klvin. His and Patt (994) also popos an mpiical ignition dlay quation: t i p0 4.50» () p Sgal (009) sows anot mpiical lation o t ignition dlay: t ign k [ O ] () w: , 5 0-0,7 k (4) and t action tim is a unction o t wall pssu distibution along t axial lngt o t combusto, P b : 75

7 ISSN nd Intnational Congss o Mcanical Engining (COBEM 0) Novmb -7, 0, Ribião Pto, SP, Bazil - 0,8 st, ,6 000 t P (5) b n x ìï n üï Pb í Pw ( x) dx x ò ëé ûù ý (6) l ïî x ïþ. CONCLUSION sult o tis ovviw is implmntd at an in ous dvlopd computational cod o scamjt ngin dsign and pomanc pdiction. icincy and combustion dlays calculation a t inputs o t ondimnsional Raylig low o combustion pdiction. pogam is usd to dsign t bot gound and ligt xpimntal ypsonic vicls, tat a bn dvlopd by t Po. Hny. Nagamatsu Laboatoy o Aotmodynamics and Hypsonics, at t Institut o Advancd Studis (IEAv). outputs om t dint solutions poposd in t psnt ovviw will b compad wit utu supsonic combustion xpimnts. 4. ACKNOWLEDGEMENS scond auto would lik to xpss gatitud to FINEP (agmnt nº , pojct nº 0445/07) o t inancial suppot o t 4-X Hypsonic Aospac Vicl dsign and xpimntal invstigations. 5. REFERENCES Andson, G. Y.; McClinton, C. R.; Widn, J. P., 990. Scamjt Pomanc. In Pogss in Astonautics and Aonautics: Scamjt Populsion, Vol. 89, pg Hamptom, USA. Diskin, G. S.; Notam, G. B, 987. "Ects o Scal on Supsonic Combusto Pomanc". In AIAA d Joint Populsion Connc. San Digo, USA. His, W. H.; Patt, D.., 994. "Hypsonic Aibating Populsion". In AIAA Educational Sis: Hypsonic Aibating Pooulsion. Wasington, USA. Klic, D.; Mundi, C., 0. "Pogss in Multidisciplinay Analysis and Evaluation o Supsonic Combustion Ramjts". In 7t AIAA Intnational Spac Plans and Hypsonic Systms and cnologis Connc. San Fancisco, USA. Muty, S. N. B., 000. "Basic Pomanc Assssmnt o Scam Combustos". In Pogss in Astonautics and Aonautics: Scamjt Populsion, Vol. 89, pg Wst Laaytt, USA. Paull, A. and Stalk, R. J., 990. "Scamjt sting in t and 4 Hypsonic Impuls Facilitis". In Pogss in Astonautics and Aonautics: Scamjt Populsion, Vol. 89. Pg Qunsland, Austalia. Sgal, C., 009. " Scamjt Engin Pocsss and Caactistics.", Cambidg, UK. omioka, S.; Hiaiwa,.; Kobayasi and Izumikawa, M., 006. "A On Dimnsional Analisys o Scamjt Combustion at Mac 6 Fligt Conditions". In 4nd AIAA/ASME/SAE/ASEE Joint Populsion and Pow. Sacamnto, USA. u, Q. and Sgal, C., 00. "Isolato/Combustion Camb intactions Duing Supsonic Combustion". In Jounal o Populsion and Pow, Vol. 6, No.. Gainsvill, USA. 6. RESPONSIBILIY NOICE autos a t only sponsibl o t pintd matial includd in tis pap. Copyigt 0 by P G. P. oo. Publisd by t st Bazilian Congss o Mcanical Engining (COBEM). 75