Conceptual design of independently configurable Mach 6.8 hydrogen fuelled dual mode scramjet propulsion system

Transcription

1 Student Researh Paper Conferene Vol-1, No-4, Aug 214 Coneptual desgn of ndependently onfgurable Mah 6.8 hydrogen fuelled dual mode sramjet propulson system Qasm Manzoor Dept. of Aerospae, CAE Natonal Unversty of Senes & Tehnology, Setor H-12 Islamabad, Pakstan Abstrat In ths researh oneptual desgn of an ndependently onfgurable dual-mode sramjet propulson system s proposed for ntegraton to a Hyperson Cruse Vehle (HCV). The propulson unt does not requre the vehle forebody to provde the ntal external ompresson, thus allevatng the dependene on the vehle geometry to sustan Sramjet operaton on an HCV. The Propulson system s desgned to propel the Booster Stage of a dervatve of HTSM 6811 vehle, whh s a Hyperson Cruser. The Sramjet system s desgned at the desgn-pont ondtons of stage separaton, for a Mxed External-Internal ompresson system wth optmal non-sentrop external ompresson surfae. The Mxed External-Internal Compresson system s then ntegrated to a onstant-area solator, onstant pressure burner and a Sngle Expanson Ramp Nozzle (SERN). One-Dmensonal Aerothermodynam method of Stream Thrust Analyss (STA) s used to alulate the performane of the Sramjet engne and asertan the Aerothermodynam propertes of flow at eah staton. The propulson system desgn s ndependent of the vehle forebody and an be ntegrated to any Mah 6.8 operatng HCV. Engne/vehle ntegraton s based on the relatve poston of sramjet engne wth respet to SERN. Ths approah allows the arflow and resultng thrust at the ombustor ext to nrease as the propulson module s moved aft and the dstane between the body and the forebody shok nreases. Keywords sramjet;dual-mode;stream analyss;ndependently onfgurable I. INTRODUCTION thrust A sramjet propulson system s a hyperson arbreathng engne n whh heat addton due to ombuston of fuel and ar, ours n the flow whh s superson relatve to the engne [1]. Unlke a 16 Al Sarosh Dept. of Aerospae, CAE Natonal Unversty of Senes & Tehnology, Setor H-12 Islamabad, Pakstan ramjet engne, the arflow n a pure sramjet engne remans superson throughout the ombuston proess and does not requre a physal hokng mehansm rather t reles on thermal oluson to provde the neessary hokng. Modern sramjet engnes are able to seamlessly transton between ramjet and sramjet operaton to norporate flght at lower Mah numbers as well. Sramjets are desgned to operate n the hyperson flght regme, beyond the doman of ordnary turbojet engnes, and fll the gap between the hgh effeny of turbojets and the hgh speed of roket engnes. Suessful sramjet desgn s dependent on areful ntegraton of engne to arframe [2],[3] beause the vehle ontrbutes sgnfantly to ompresson and expanson omponent performane. An ndependently onfgurable sramjet engne would provde propulson to any vehle operatng at the desgn Mah for the engne. In ths paper, a sramjet propulson system s desgned to fulfll the propulson requrements for the booster stage of HTSM 6811 whh s orgnally a roket ramjet propelled vehle [4]. The propulson system has ts own forebody ompresson ramp and SERN whh an be ntegrated to the hyperson ruse vehle at an approprate loaton. The forebody s desgned to over a wde range of operatng ondtons, for ths reason the seleton and optmzaton of hyperson forebodes s a rtal researh area and many methods an be used for ths purpose [5]. In ths study, the ramp s evolved usng the yle stat temperature rato and omparng t aganst a sutable value of burner entry Mah number [6]. The ramp angle whh gves a

2 Coneptual desgn of ndependently onfgurable Mah 6.8 hydrogen fuelled dual mode sramjet propulson system reasonable Burner entry Mah number s seleted and the orrespondng yle stat temperature rato s hosen as the desgn yle stat temperature rato [1]. Stream thrust analyss s performed at the seleted value of to alulate the performane and varous aerothermodynam parameters at eah staton [1],[7]. Isolator length s determned by alulatng the shok dstanes [8] at desgn pont and burner length s fxed by alulatng the requred [1] mxng length and norporatng Raylegh effet [8] to model the heat addton proess n the burner assumng zeroshear mxng layer [9],[1]. SERN s desgned usng the method of haratersts whh resolves hyperbol PDEs nto ordnary dfferental equatons [11], [12] and allows the Prandtl Meyer fans n the expanson omponent to be resolved and Mah numbers n ths omponent to be alulated wth reasonable auray. Engne ntegraton to the vehle s done by the method spefed by Curran [13]. Ths method allows a dual-mode sramjet propulson system to be desgned ndependent of the vehle geometry and then ntegrated to provde propulson at the desgn Mah of 6.8 even for vehles whh are not prmarly desgned for sramjet propulson systems. Fg. 1. HCV for Sramjet Integraton (Independently Confgurable) The ramp angle s alulated by evaluatng the yle stat temperature rato and burner entry Mah number for a range of ramp angles and the ramp angle gvng a sutable burner entry Mah number s seleted. After the ramp angle has been seleted, Stream Thrust Analyss s performed for the orrespondng to the seleted ramp angle to alulate aerothermodynam parameters of the flow and to determne the performane of the engne. Fg. 2 gves the referene staton numbers used durng the stream thrust analyss: II. METHODOLOGY In onventonal sramjets the vehle forebody provdes the external ompresson, but n the ase of the vehle under study the orgnal forebody ramp of the vehle does not provde enough ompresson to ensure effent sramjet operaton whle satsfyng the shok-on-lp ondton. So a dfferent approah was appled n whh a forebody ramp for the sramjet engne was desgned. The shok orgnatng from the vehle forebody would not be ndent on the lp n ths ase rather the shok orgnatng from the engne s own ramp would satsfy the shok-on-lp ondton. The freestream ondtons for the vehle are the stage separaton ondtons for the HTSM 6811 vehle.e. Mah 6.8 at 35km alttude. But the effetve freestream ondtons for the engne are the downstream ondtons after the oblque shok orgnatng from the 2.5 o vehle forebody ramp Fg. 2. Sramjet Referene Staton Numbers The geometry.e. lengths and areas of the varous subomponents of the sramjet engne are then alulated. For the solator length, shok dstane for the refleted shok nsde the nlet s alulated for the seleted ramp angle at desgn ondton. The ombustor length s alulated by multplyng the mxng length by 1.5 where the mxng length gven by: L m Lm s 2 ub (1) 16 D 17

3 Coneptual desgn of ndependently onfgurable Mah 6.8 hydrogen fuelled dual mode sramjet propulson system Here D s a proportonalty onstant alled moleular dffusvty u mean veloty of nomng ar fuel mxture b s nlet fuel jet dmenson D s gven by Fk s law [14], and an be estmated by the formulaton. S (2) D Fg. 4. Ramp Angle vs. Combustor Mah No. / ψ Seletng the at the pont of nterseton orrespondng to a ramp angle of 16.5, stream thrust analyss s performed for onstant pressure burner onfguraton at the engne freestream ondtons. The results obtaned from the STA are: Table I. STA ψ=3.36 Fg. 3. Shemat Dagram of the Ideal Exhaust Nozzle The SERN s desgned usng the method spefed by Heser [1], where the Mah numbers for eah zone n the fgure are alulated and the flow turnng angles neessary to obtan the Mah numbers are alulated wth auray by solvng the Prandtl Meyer fans that wll exst n the expanson omponent and ther nteraton wth eah other. III. RESULTS Iteratve alulatons for and the burner entry Mah number for a range of ramp angles from.5 to 25 degrees yelds the followng plot: Parameters Statons Staton Staton 3 Staton 4 Staton 1 M V (m/s) T (K) P / P A / A Sa (Ns/kg) The performane measures alulated from the results of the STA are: Table II. Performane Measures of Engne Performane Measure Spef Thrust Ns/kg Overall Effeny.34 Propulsve Effeny.9435 Thermal Effeny.358 I sp s 18

4 Coneptual desgn of ndependently onfgurable Mah 6.8 hydrogen fuelled dual mode sramjet propulson system The lower Mah lmt of sramjet operaton for the dual mode sramjet engne s determned to be M =3.78 usng the relaton: M T T 3 1 (3) Forebody ramp geometry along wth Isolator Length and Burner Length are alulated usng MATLAB ode whh generates the geometry n Fg. 5. the Prandtl Meyer expanson fans s gven n Table IV: Parameter Table IV. SERN Charatersts o M III L.94m II o III L 2.437m IV H H After the geometry parameters are alulated a 2- Dmensonal model of the sramjet engne n generated and s gven n Fg. 6 Fg. 5. Inverted Sramjet Geometry (Forebody, Isolator, Burner) The mportant geometr parameters obtaned from the MATLAB ode and Fg. 5. Are lsted n Table III Parameter Isolator Heght Isolator Length Burner Length Table III. Component Geometry Parameters Burner Area Rato m.517 m 6.41 m A A 3.95 Fg Dmensonal model of Sramjet Fnally the engne s ntegrated to the vehle at n suh a way that the start of the forebody ompresson ramp les at an x/l=.5 and the start of the SERN les at an axal loaton of x/l=.647 The heght of solator s alulated from the area of the nlet whh s determned from the mass flow rate at the nlet, where the wdth of the nlet s 17.3 m. The mass flow rate s determned to be kg/s from the spef thrust value for an nstalled vehle thrust of 4kN. The results obtaned from the SERN alulatons by applyng the method of haratersts to solve Fg. 7. Sramjet ntegrated wth vehle IV. CONCLUSION The sramjet engne desgned by followng the above method s fully onfgurable to the vehle for 19

5 Coneptual desgn of ndependently onfgurable Mah 6.8 hydrogen fuelled dual mode sramjet propulson system whh t was desgned and the dmensons of the engne are ompatble wth those of the booster stage of the HTSM The forebody ramp of the desgned sramjet an be ntegrated wth the ramp of the vehle forebody and the SERN, wth a turnng angle of 26.2 o, an be adjusted to onform to the 11 o ramp at the exhaust of the HTSM 6811 by means of sentrop expanson whh wll gve the surfae of the SERN. The engne length s 1/5 th of the total vehle length whh s typal for sramjet engnes [13]. The sramjet engne an be ntegrated to the vehle at the aftmost loaton before the exhaust ramp of the orgnal vehle starts for the reason that ths loaton wll allow the arflow and resultng thrust at the ombustor ext to be the hghest along wth the added beneft of nreasng the dstane between the vehle forebody shok and the nlet of the engne. V. REFERENCES [1] W. H. Heser and D. T. Pratt, Hyperson arbreathng propulson: AIAA, [2] R. Hallon, "The Hyperson Revoluton Vol. I: From Max Valer to Projet PRIME ( )," Ar Fore Hstory and Museums Program, Bollng, AFB, DC, [3] R. Hallon, "The Hyperson Revoluton: Eght Case Studes n the Hstory of Hyperson Tehnology, Vol. 2, Speal Staff Offe, Aeronautal Systems Dv., Wrght-Patterson AFB, OH, 1987, pp " [4] D. Jaob, G. Sahs, and S. Wagner, "Bas researh and tehnologes for two-stage-to-orbt vehles," ed: Wenhem: Wley-VCH, 25. [5] A. Sarosh, C. Sh-Mng, and D. Yun-Feng, "A dfferene-fratonal FOM deson method for downseleton of hyperson ompresson system onfguratons," Aerospae Sene and Tehnology, vol. 27, pp , 213. [6] G. C. Oates, Aerothermodynams of gas turbne and roket propulson: Aaa, [7] E. T. Curran and R. R. Crag, "The use of stream thrust onepts for the approxmate evaluaton of hyperson ramjet engne performane," DTIC Doument1973. [8] A. H. Shapro, "The dynams and thermodynams of ompressble flud flow," New York: Ronald Press, , vol. 1, [9] A. Sarosh, D. Y. Feng, and M. Adnan, "An Aerothermodynam Desgn Approah for Sramjet Combustors and Comparatve Performane of Low- Effeny Systems," Appled Mehans and Materals, vol. 11, pp , 212. [1] O. Planhé and W. Reynolds, "Heat release effets on mxng n superson reatng free shear-layers," AIAA Paper, [11] G. Emanuel, "Gasdynams: theory and applatons," New York, Ameran Insttute of Aeronauts and Astronauts, In., 1986, 46 p., vol. 1, [12] G. J. Harloff, H. La, and E. Nelson, Two-dmensonal Vsous Flow Computatons of Hyperson Sramjet Nozzle Flowfelds at Desgn and Off Desgn Condtons: Natonal Aeronauts and Spae Admnstraton, [13] E. Curran and S. Murthy, Sramjet propulson vol. 189: AIAA, 2. [14] R. B. Brd, W. E. Stewart, and E. N. Lghtfoot, Transport phenomena: John Wley & Sons, 27. 2