E AME ICA SOCIE Y O MEC A ICA E GI EE S 2 G 40 4 E. 4 St., Y r , .Y. 00
h S t h lt n t b r p n bl f r t t nt Of p n n dv n d n p p r r n d - n t t n f th S t r f It v n r S t n r pr nt d n t p bl t n n pr nt d nl If th p p r p bl h d n n ASME rn l p r r v l bl fr ASME f r f ft n nth tt r th t n r nt d n USA Copyright © 1992 by ASME
A S p n St d f r p r n r n p rt
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SIMIO C. KUO, AY . OE AC nd GEO GE C AM AG E r tt Wh tn —GES W l h A. A A A nd . U AMU A K v Ind tr C td K b p n Y. WA A A E I h j - r v Ind tr C td p n . AOKI M t b h v Ind tr C td p n
A S AC I O UC IO Hypersonic aircraft and their propulsion systems are The need for hypersonic aircraft arises from the desire exposed to severe aerothermal environments which require a to shorten the length of travel time for Pacific Rim, system approach to create innovative designs able to respond Trans-Atlantic, and Europe-Asia flights which can require to the environmental challenges. This paper describes a up to 12 or 14 hours of subsonic flight. Mach 5 hypersonic preliminary study used to scope the technical challenges and flight would reduce the block time of these long flights to less identify the necessary development plans for the aircraft than 3 hours. As discussed in Reference 1. hypersonic flight propulsion system. Presented here are the interim results of is possible using a turboramjet propulsion system; but as this scoping study for a turboramjet conceptual design explained in Reference 2. the turbojet must be protected from conducted by UTC, Pratt & Whitney. This study is the first of the ram air stagnation temperature at Mach 5 speeds. four phases in a 6 year program on Hypersonic Transport References 3. and 4. conclude that aircraft inlet, Ramjet (HYTRAM) system R&D sponsored by NEDO, as an turbojet, ramjet and nozzle integration is a complex process integral part of the Japanese National Project on and that this integration becomes more important as flight "Super/Hypersonic Transport Propulsion Systems (HYPR)". speed increases. This type of large, high speed aircraft, as Various turboramjet configurations were evaluated pointed out in Reference 5., raises concern for atmospheric and two attractive candidates, a co-axial and a split flow pollution, noise and the problem of fitting into the existing configuration, were selected. Performance analyses were world airport infrastructure. conducted for these two by incorporating the subsystem Past approaches using airbreathing propulsion engine performance data provided by the Japanese companies (IHI for supersonic flight include existing commercial and on the turbofan and M I on the inlet and nozzle). military applications. The most well known applications are Pre-conceptual mechanical design sketches were prepared to the commercial Mach 2 Concorde and the military Mach 3+ provide some elementary definitions of the co-axial and the SR-71 Blackbird. There are also several Turboramjet split flow turboramjet to assist in selecting a baseline programs such as the Lockheed Mach 5 Penetrator, the configuration. Candidate materials including composites for General Dynamics Mach 5 INCAAPS, The Boeing Mach 4-6 the major subsystems were selected, using metals for Interceptor/Reconnaissance Aircraft, and the Mach 5+ near-term applications and including ceramics for far-term NASA Himate. applications. Using the above results from this scoping study, the co-axial configuration was selected as the baseline Previous manned supersonic aircraft such as the because of its higher Figure of Merit estimated from its Concorde and the SR-71 are limited to Mach 3+. However, performance, mechanical design characteristics and the a hypersonic aircraft equipped with the HYTRAM engines technical challenge it presented. will fly at Mach 5 which will encounter a much more hostile
r nt d t th Int rn t n l G rb n nd A r n n C n r nd Exp t n C l n G r n n 1- 199 environment. These propulsion systems, therefore, require Details of a typical flight shown in Figure 2 can be careful assessments of the operating conditions and used in designing the propulsion system and aircraft. The incorporate innovative approaches to the design of the cruise portion shown is for a Mach 5 aircraft speed at an propulsion engine with adequate cooling and minimum altitude of 27 Kilometers. The figure also shows that a fuel environmental effect. reserve of 5% has been included as well as a subsonic cruise This paper presents the interim results of a one-year leg flying at Mach 0.9 at an altitude of 9.0 kilometers plus a preliminary Ramjet Conceptual Design Scoping Study to 30-minute hold at 4.5 kilometers. ensure that the technological requirements are put in perspective so that a clear program direction and specific technical tasks could be established.
The relative performance and mechanical complexity Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 of several Mach 5 methane fueled turboramjets were examined. Pre-conceptual designs were conducted for a co-axial and a split flow configuration to identify the thermal, mechanical, and structural requirements of a Mach 5 propulsion system. A baseline turboramjet cycle configuration was then selected jointly with other HYPR contractors; this preliminary conceptual design configuration is a co-axial arrangement where the ramduct surrounds the turbofan and valving is used to direct the airflow into either the ramjet or the turbofan or both. FIG. 2 TYPICAL FLIGHT PROFILE/RESERVE The turboramjet propulsion performance has been REQUIREMENTS calculated to define the operation of the engine throughout its required flight regime. The baseline preliminary design Depletion of the high atmosphere ozone layer has analysis was conducted to determine materials and inlet and become an issue of critical importance. Figure 3 presents nozzle integration requirements and to define a thermal ozone concentration as a function of altitude and shows a management scheme. maximum at about 20 km. Pollution by NOx emissions of the Environmental protection from noise and air ozone layer through combustion of hydrocarbon fuels, such pollution must be seriously considered. Solutions such as as methane (CH4), is thought to aggravate the depletion and large engines with low exhaust speed will benefit noise and since this transport cruises at 27 km, it will pass into these holding combustion temperatures to less than stoichiometric layers where NOx emissions control must be considered. will benefit Nox formation. These and other options will be considered as the study progresses. S A OS E IC O O E E IO SY O: EMISSIO S Finally, using information generated by the study, the critical technologies required to develop this turboramjet 42000 OS U A E CA AI WIC M C A ISM O + 3 O + 6000 • • O + O engine concept to practical operation have been identified. + ( E
0000 HYPERSONIC TRANSPORT CHARACTERISTICS — M h .0 24000 M d, 4.0 — M h .2 Hypersonic transport characteristics have benefits p — M h 2.4 and drawbacks on the intended mission. The advantage of — M h 2.0 hypersonic trips to various popular destinations can be seen 2020 S b n fl t in Figure 1; a conventional flight, over the longest market 60006000 routes, of 12 hours could be reduced to 3 hours using a Mach
5 transport. 0.2 0.4 C n ntr t n ( M,
FIG. 3 OZONE CONCENTRATION VERSUS ALTITUDE
TURBORAMJET CONFIGURATION ALTERNATIVES Twelve configurations using various combinations of inlet, turbofan engine, ram duct, ramjet burner and exhaust nozzle options were evaluated. The best co-axial flow and the best split flow turboramjet configurations were identified as candidates for the baseline selection. Efforts to select initial turboramjet configurations for study began by FIG.! TYPICAL CITY PAIRS & ESTIMATED BLOCK grouping the five components to form 12 candidate TIME REDUCTIONS - MACH 5.0 CRUISE configurations thought to be possible and workable. These
2 TABLE 1. ASSUMPTIONS FOR PERFORMANCE configurations included variations of all the turboramjet EVALUATION subsystem options discussed above. The selections were made using combinations of components thought to be • r th n f l (C f l h t n v l = 9 5 j/ workable. The 12 selections were judged using 23 • G p t nt l lt t d considerations and ranking each accordingly. From these 12 • U S t nd rd t ph r 197 t bt n b nt nd t n turboramjet configurations, the best co-axial flow and the • Inl t t t l nd t n l l t d b d n d b t best split flow configuration were chosen for performance nd ntr p pr evaluations. • M I nl t t t l pr r r r v r b l M h 1 37 MI -E 5 7 b v M h 1 37
• En n nl t rfl h d l d f n d b I I (t rb Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 f n d nd KEII (r j t d Figure 4 shows the co-axial turboramjet • M I n zzl nt rn l p rf r n (t rb f n (Cv= 97 configuration and Figure 5 shows the split flow turboramjet r j t Cv= 95 configuration chosen for further evaluation. The co-axial • t r bl d r h r p r xtr t n turboramjet is shown in both the turbomachinery only (top) and the ramjet (bottom) modes of operation. The ramjet Table 2 shows the operating Mach number ranges for burner is located downstream of the turbofan and is used to both selected configurations and shows where each augment the turbofan flow during dual, i.e., combined component operates. The turbofan operates in the low Mach turbofan/ramjet operation. A common 2D nozzle is used for number range, both the turbofan and the ramjet (noted as both the turbofan and ramjet. In the split flow configuration dual) operate in the mid Mach number range, and the ramjet the ramjet is separated from the dry (non-augmented) alone will be used for propulsion in high Mach number flight. turbofan. TABLE 2. TURBOFAN/RAMJET OPERATING MODES Mach No. Mode Co-Axial Split-flow Turbofan 0-3.0 0-2.5 Dual 3.0-3.5 2.5-3.0 Ramjet 3.5-5.0 3.0-5.0
FIG. 4 CO-AXIAL TURBORAMJET Performance calculations made for the co-axial CONFIGURATION configuration are tabulated in Table 3 at Mach Numbers and altitudes within the flight profile.
TABLE 3. CO-AXIAL RAMJET OPERATION (UTC)
M h b r 2. .0 4.0 .0 .0 Alt t d , 8. 20. 24.8 2 . 2 . r S tt n Cl b Cl b Cl b Cl b Cr Inl t 0 4 2 2 6 6 r r , Inl t 486 604 0 2 4 2 4 p r t r , °K FIG. 5 SPLIT-FLOW TURBORAMJET Inl t C r. 6 4 4 84 2. 2. CONFIGURATION l , Inl t G 4 402 280 286 286 l , Inl t M h 0.4 0. 0 0. 0.06 0.06 b r PERFORMANCE EVALUATION Ex t M h 0. 0.4 0. 6 0.0 4 0.06 b r A preliminary performance evaluation of the co-axial l A r 0.00 0.0 8 0.022 0.02 0.0 8 and split flow turboramjets was completed and the required t design flight conditions were identified. Table 1 lists the E v l n 0. 0.2 0. 0.44 0. 2 assumptions made for doing these performance evaluations. t C b t n Eff n , %
3 C ld r r 0. 0.08 0.0 4 0.004 0.004 t r r 0. 24 0.06 0.008 0.00 0.00 Ex t 8 24 2 208 8 6 p r t r , °K t hr t, f 0 , 0 2800 2,4 0 86 0 S C, . 8 .64 .80 2. 2. 8 hr f
The engine inlet corrected flow schedules used for turbofan, dual and ramjet modes of operation are presented in Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 Figure 6. The turbofan schedule up to Mach 3 was provided by IHI and the ramjet flow schedule was provided by KHI. The co-axial turboramjet operates in the turbofan only mode below Mach 3, as shown in Table 3, because the turbofan produces more thrust at a lower TSFC, as shown in Figures 7 and 8. The thrusts shown in Figure 7 reflect all the inlet flow passing through either the ramjet or the turbofan. Above Mach 3, the turbofan thrust is significantly reduced and the ramjet must be turned on to maintain an adequate rate FIG. 8 TURBOFAN AND RAMJET TSFC LEVELS of climb and acceleration. Figure 9 illustrates the thrust and TSFCs that are achieved during dual mode operation when the ramburner is lit and augments both the turbofan and ramjet flows. At Mach 3.5, the turbofan is shut down and the S C engine operates as a ramjet. hr t 1 5 l
1 Id U O A A A (
00 lk 0 . 00 00 t hr t Q - ll 1 - 1 4000 0 . A E A A (K I
1 •
5 3 3 5
l ht M h b r
FIG. 9 CO-AXIAL TURBORAMJET PERFORMANCE The split flow turboramjet operates in the turbofan mode below Mach 2.5 and transitions to the ramjet mode at Mach 3. Figure 10 compares dual mode performance with turbofan and ramjet only performance between Mach 2.5 and 3.5. Because the turbofan is not augmented, the dual mode thrust above Mach 3.0 is less than that which can be achieved in the ramjet only mode. Therefore, the transition must be made before Mach 3.0. The TSFCs during dual mode operation are higher than these of the turbofan or ramjet because the ramjet must be operated at its maximum fuel air ratio to maintain adequate thrust.
Figure 11 compares the co-axial and split flow turboramjet TSFC between Mach 2.5 and 3.5. The co-axial turboramjet powered aircraft will burn less fuel because of its 3 3 3 significantly lower TSFC. MAC UM E FIG. 7. TURBOFAN AND RAMJET THRUST LEVELS
4 MATERIALS REQUIREMENTS - S C K I MAY-1 The Scoping Study work also included materials selection and developed pre-conceptual layouts for a 1 5 co-axial and a split flow turboramjet. The thermal, mechanical, and environmental conditions were identified to 1 permit materials selections. Selection of materials suitable for the inlet, ramburner and nozzle, for near and far term use,
1 have been made and are shown in Figures 12, 13, and 14.
Figure 12 shows that the inlet diffuser section could Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 O hr t 1 - use lightweight titanium alloys for structure and Haynes 230 - for liners using appropriate cooling.
93 -
5 3 3 5 l ht M h b r FIG. 10 SPLIT-FLOW TURBORAMJET PERFORMANCE
2.0 COA E ICKE I E S I AY ES 2 0
n = 1 C .8
1 S C FIG. 12 CANDIDATE MATERIALS FOR THE /hr- t INLET/DIFFUSER 1
I rh t Figure 13 shows the nozzle, flameholder, and support 1 K j t structures with the candidate materials suggested for each. A Sp lt l (d l d MA 6000 is suggested for the support structure where • C -Ax l l (d l d temperature is high and oxidation resistance is required. 1 2.0 2 . .0 . 4.0
l ht M h b r FIG. 11 SPECIFIC FUEL CONSUMPTION COMPARISON
r / x Of S C S6 4 Table 4 presents the minimum and maximum values of ramburner operating parameters which were used in this COO E COA E ICKE A OY first phase of the scoping study to select materials and define 0.0 a cooling system for a co-axial turboramjet.
COA E ICKE A OY II TABLE 4. CO-AXIAL RAMBURNER OPERATING 0.0 REQUIREMENTS (KHI DATA)
MI AM l ht M h b r 5 5 FIG. 13 CANDIDATE MATERIALS FOR THE FUEL Inl t r r 7 55 NOZZLE/FLAMEHOLDER Inl t p r t r °K 1 71 / Inl t M h b r 1 Methane fuel contains small amounts of sulfur and C ld r r (A / 15 therefore Haynes 230 can be used to provide sulfidation and oxidation resistance. For the flameholder, Inco 900 is Eff n % 99 99 suggested with a heat shield to give it hot gas protection. l A r t 55 Figure 14 shows candidate materials for the E v l n t (f/ / 5 turboramjet nozzle. They are MA 956 for high temperature Ex t p r t r °K 7 1 1 oxidation resistant liners and MA 6000 as the high strength C ld r r = t r b n r nl t M h b r f 3 structural material.
5 Figure 17 shows a candidate ramburner which is piloted and has fuel jets incorporated in the radial flameholders. This configuration has predicted high combustion efficiency and will provide ignition as needed over the flight envelope.
COO E U E S UC U E MA sea WI C I E E < 0C A SU ACE ICKE S UC U E MA 6000
E <8 0.0 Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 l = 40.4 x 04 000C E . = 8.2 x 0 000C r x d l t d l h ld r Addr th FIG. 14 CANDIDATE MATERIALS FOR THE r b l t St b l t E n I NOZZLE
Design Considerations
O S AY A Pre-conceptual design sketches for the co-axial and the split flow turboramjets were prepared and used in beginning to produce a baseline conceptual design sketch. Detail features of the baseline design include cooling for ramcombustor walls and the injectors and flameholders for the ramburner. Figure 15 shows a ram combustor wall made of metal and film cooled with air to protect it against the hot combustion gasses while Figure 16 shows a ram combustor wall made of ceramic and high temperature insulation to protect the structure against the hot combustion gasses.
FIG. 17 CANDIDATE RAMBURNER Al M t l p n nt l C l n
%WC , C b t n G
M nd rn C l% r WC Baseline Engine Configuration Selection
C ndl l n d r •C A rating process involving 9 Evaluation Factors with — l C l ‘6 •C l each further broken down into 2 to 4 rating parameters was proposed to select the baseline configuration. Figure 18 shows the work sheet for rating the evaluation parameters and 6 400.0 the Figure of Merit (FOM) to be computed based on the Ext rn l At ph r Weighting Factor to be assigned. Scoring of 1 to 4 with 4 best FIG. 15 NEAR TERM COOLING STRUCTURE FOR was suggested for each parameter, determined by ranking HYTRAM RAM COMBUSTOR WALL both intrinsic and relative merits, according to the guideline shown in Figure 19. The intrinsic ranking may be thought of h p r t r C r n r d t n C l d Str t r as the absolute merit of the design and this may be either good C b t n G or bad; while the relative merit judgement is made in relation GSM t Ab 660•C to the other design as to whether it is better or worse than the n p Cl l 0 M t r l one in question. A In the actual selection process participated by all
E E In d l n parties concerned and summarized in Figure 20, the 9 evaluation factors were reduced to 6 and the total evaluation paramerters were reduced to 14. Based on the weighting
n b assigned to each of the 6 factors, considering their individual 40060 Exp nd d &d Enh n d importance, the co-axial system was rated to have the highest . • 0•C FOM, whether weighted or not, and accordingly was selected Ext rn l At ph r as the baseline for future effort. FIG. 16 FAR TERM COOLING STRUCTURE FOR HYTRAM RAM COMBUSTOR WALL
6 to the other design as to whether it is better or worse than the W GI one in question. AC O AC W A AME E S CO A IA S I OW I. Env r n nt 2 . Ern l n . 4 .0 In the actual selection process participated by all .2 40 0 (2. (2. 2.Ov r ll 4 . l 2. 4 . " . parties concerned and summarized in Figure 20, the 9 rf r n .2 rpl nt 4 (4.0 ( .0 evaluation factors were reduced to 6 and the total evaluation . n 2 . r r d n . .6 2 " . .2 h r l M n nt ( .26 (2. paramerters were reduced to 14. Based on the weighting . r n t n C ntr l .4 M n f t rIn assigned to each of the 6 factors, considering their individual C t 8 d 4. hn 2 4. Ev h t n f K .6 4.0 . . importance, the co-axial system was rated to have the highest Ch ll n C p n nt hn l (4.0 ( .0 4.2 Ev l t n f K FOM, whether weighted or not, and accordingly was selected S t hn l . as the baseline for future effort. .Int r t n 0. . A rfr n t ll t n l. 4.0 . . .2 Ext rn l In t ll t n ( .0 (2. Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 O. Op r t n 0. 8. r bl lr .0 . . 2.0 4.0 l b l t ( . (2 .2 M nt n b l t r f M rtt .0 2. 8 W ht d ( .4 2 (2.0 Wt. E A UA IO ✓ r t r r f M r t 2. 24 2. 4 AC O Un ht d ( .042 (2.2 2 . Env r n nt E n
2. rf nt FIG. 20 SCORE SHEET FOR SELECTING BASELINE IS 2 COMBINED CYCLE ENGINE CONFIGURATION . n S pl t r r d n Sp ll CONCLUSIONS Str t r Int r t
4. S t II W ht x ht nd W dth n th r nt l Ar The following conclusions have been derived from W ht the major findings and observations during the Conceptual S. Int r t n C p n nt b t Design Scoping Study for the Y turboramjet propulsion A rfr system. 6. h n l M n nt . llllll C l nt th S ll t Ar 1. There are no fundamental technological barriers t p I E fffff 60, 4 x which prohibit the development of a Mach 5 . hn l hypersonic transport propulsion system. O •l nt M:t rf l ::: :: : A However, the first hypersonic revenue flight may
S. Op r t n be 20 or more years away, and its commercial M O r lllll t C ntr l l t Op r b ll t operation will have to compete with the A b l t v b l t Un lllll t rt supersonic and wide-body subsonic transports . C t v l p nt market, perhaps for the trans-Pacific and Un t f C l Asia-Europe routes applications. r f r t OM = W ht d W 2. Some of the critical technologies which require 0 M = priority are: • ht ht h h t p r t r p t t r l • h t p r t r l br nt nd p n nt FIG. 18 WORK SHEET FOR SELECTING BASELINE TRJ CONFIGURATION • h p rf r n d r bl r j t f l nj t r/fl h ld r • M h 5 v r bl tr nl t nd xh t n zl t • h t p r t r l d n l f r v r bl tr SCO E Intr n M r t l t v M r t 0 • On-b rd r n f l t r n l t n nd OI S tr n n 3. A preliminary screening of numerous turboramjet G d d tt r W r configurations has concluded that both the 4 co-axial and split flow concepts are viable, the choice of which depends on the design criteria, operational requirements, the flight profile/ 2 envelope desired and the progress in high-temperature, lightweight, and high-strength materials (composites) development. -3 C p r n b t n th - x l nd pl t fl n n nf r t n 4. The conceptual design layouts have verified possible configurations for both the co-axial and FIG. 19 GUIDELINES FOR SCORING INDIVIDUAL split flow engine concepts. The layouts have RATING PARAMETERS highlighted the need for design criteria to
7 integrate the various components. Definitions of REFERENCES the accessories and their locations are needed to make the conceptual design more realistic. Wotel, G.J., Gallagher, ICE., Maurice, L.Q., 5. The co-axial turboramjet was chosen as the "High-Speed Turboramjet Ramburner Technology baseline configuration for further design studies Development", UTRC Report under contract No. based on the Figure of Merit (FOM) calculated 1;33615-87-C-2702 with Wright research and Development from the ratings made by HYPR participants for Center. the selection parameters and weighting factors Ward, B.D., Hewitt, F.A., AIAA-88-3069 "High proposed. This configuration offers the potential Speed Airbreathing Propulsion", July 11-13, 1988. for lightweight and good fuel economy, but
Sakata, K., Honami, S., Tanaka A., AIAA Paper Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1992/78941/V002T02A032/2401615/v002t02a032-92-gt-409.pdf by guest on 02 October 2021 requires innovative control and accessibility 91-2012, "Supersonic Air-Intake Studies Aiming at the designs, and requires a dual-mode range of Mach Future Air-Breathing Engine", June 24-26 1991. 3 to 3.5. Salemann, V., Andrews, M., "Propulsion System Integration For Mach 4 to 6 Vehicles". ACKNOWLEDGEMENT Domack, C.S. et al, NASA Technical Memorandum 4223, "Concept Development of a Mach 4 High-Speed Civil The many guidances and supports received from the Transport", 1990. Japanese sponsor and the contractors, particularly from NEDO (Mr. Ishizuka) and HYPR Research Association are gratefully acknowledged.
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