Rocket Fuel R&D at AFRL: Recent Activities & Future Direction

Transcription

1 Rocket Fuel R&D at AFRL: Recent Activities & Future Direction Matt Billingsley Air Force Research Laboratory Combustion Devices Branch 12 April, 2017 DLA Worldwide Energy Conference National Harbor, MD

2 Emphasis: Rocket Kerosene Fuels Chemical Propulsion Solid Rocket Motors (SRM) Liquid Rocket Engines (LRE) Storable (IRFNA, MMH) Cryogenic (Liquid O2/fuel) Hydrocarbon Hydrogen (LNG/CH4, kerosene) RP-1, RP-2 2

3 Rocket & Jet Fuel Shared Challenges Complexity distillate/blended fuels Descriptive chemistry/property correlations Accurate properties/models for CFD design Multipurpose fluids cooling, burning, Fuel reactivity and material compatibility Specification test methods & limits 3

4 Engine Comparison Engine F119-PW-100 RD-180 F-22 Raptor Atlas V Thrust (lb) 35,000 a 860,000 b Weight (lb) 3,900 Vehicle c 12,000 T/W Ratio Length (in.) Diameter (in.) a,c Fuel usage (GPM) a With afterburning b At sea level 6,500 c b Estimate 4

5 Rocket Cycles and Environments Ox-Rich Staged Combustion Cycle Gas Generator Cycle ~30,000 RPM P ~ 12,000 psi Fuel-Rich Combustion Φ ~ T ~ 400 F >100 gal/s SpaceX Merlin 1D 190 klbf Throttleable Russian RD klbf Rocket fuels perform multiple functions in extreme operating environments with no room for error 5

6 Historical Context for Fuel R&D RP GG <200 klbf LR79-7 LR89-5 RP 1970 RP 1980 H2 ORSC Studies RS-76, 900 klbf RS-84, 1 Mlbf RP RP GG GG FFSC 1.5 Mlbf 200 klbf 1.5 Mlbf F-1 RS-27 RS-25 Meanwhile, in Russia 1990 RP 2020 RP CH4 GG Development 190 klbf AR1, 500 klbf Merlin Raptor, 670 klbf BE-4, 540 klbf RP ORSC RD-170/180, 800 klbf U.S. hasn t developed or built high-pressure LOX/HC engines in a long time 6

7 Current Motivation Replacing RD-180 National decisions steer R&D New commercial space entrants SpaceX Raptor: 1st LOX/HC FFSC Engine Aerojet Rocketdyne AR1: 1st U.S. LOX/RP ORSC Engine Variation in engine cycle & propellant chemistry Emphasis on affordability & reusability Modeling & Simulation CFD simulations shorten the test-fail-fix loop Key to development Requires accurate models Blue Origin BE-4: 1st U.S. LOX/LNG ORSC 7

8 Rocket Grade Kerosene Highly refined specialty hydrocarbon mixture Hydroprocessed narrow middle distillate blend 300 F Heavy Naphtha IBP F Kerosene 10% FBP RP-1 Jet A Two specification grades: RP-1 & RP-2 Produced for missiles and orbital launch vehicles since late 1950 s with only minor spec changes Source: DLA Energy PQIS 2013 Annual Report 8

9 Low-Volume Market with High Stakes ~0.01% of annual jet fuel production (2.3B gal/year) Produced on-demand Payload: $0.5B - 2B yr. Limit launch site inventory Alternative source R&D Launch Vehicle: $40M - 100M Fuel is <1% of total cost Vehicle-dependent Costly consequences for performance differences Cost-saving arguments previously difficult Reusability Fuel: $100k Strong case for performance improvements 9

10 Specification Fuel Specification Requirement, Units Distillation, C IBP 10% recovered 20% recovered 50% recovered 90% recovered End point Density/15 C, kg/l Viscosity/-20 C, mm2 /s Flash Point, C Freezing Point, C Net Heat of Comb., MJ/kg Hydrogen, mass % Aromatics, vol % Olefins, vol % Total sulfur, mass% Mercaptan sulfur, mass% JFTOT ΔP change, mmhg JP-5 Jet A RP-1 RP-2 MIL-DTL-5624U ASTM D MIL-DTL-25576E MIL-DTL-25576E <205 report ( ) report ( ) report report (<274) <16.5 (>60) (<-51) (>43.0) >13.8 <5 <2.0 <0.003 < report report (<274) <16.5 (>60) (<-51) (>43.0) >13.8 <5 <1.0 < Method ASTM D86 D1298 D445 D93 D2386 varies varies D1319 D1319 varies D3227 D3241 report <205 report report report < <8.5 >60 <-46 >42.6 >13.4 <25.0 report report < <8.0 >38 <-40 >42.8 >13.4 <25.0 <0.3 <0.002 <25 <0.3 <0.003 <25 report 10

11 Historical Consistency Composition 1957 ca Boiling Range/Volatility 11

12 Compositional Variation n-c8 C9 C10 C11 C12 C13 C14 C15 C16 RP-2 (POSF 5433) Physical, chemical properties (ρ, μ, ΔHc, etc.) govern composition RP-2 (7688) RP-1 (5235) JP-8 (4751) JP-7 (3327)

13 Fuel Complexity Closer View RP-1 GCxGC Chromatogram 13

14 Impurities/Contaminants - Sulfur Method RP-2 (4) D5453a D4045 RP-2 (1) RP-1 (2) <0.02a 10e, 7a,b a <0.1a <200a,c 6.7, 14e D2622 0±0 RP-2 (1) Mfg report Repeat test c 2001 spec: 200 ppm d 2σ, 3 runs ea. e Private lab analysis b D4294 GC/SCDd RP-1 (18) 3.7 ± ± ± 15.2 RP-1 (18) 14

15 Impurities/Contaminants - Oxygenates RP-1 Polars Analysis JFTOT (5 hr., 355 C) Fuel 160 (200) 19 (24) 19 (24) 23 (29) Max ΔP (mmhg) Max ΔTDR (Spun) 35 a 38.1a 16.6b 5 repeat test, b 0.1a 0 0 0b filtered sample Aliphatic ketones mg/l (ppm) Phenols mg/l (ppm) ketones phenols phthalates Internal Standard Butoxy-ethanol Phthalates Time--> JFTOT tubes

16 Alternative Formulations canola Fuel A, Isp 300.0s RP prototype, Isp ~300s Fuel B, Isp 301.8s Small performance gains can be huge for payload 16

17 Fuel Properties 17

18 Properties of Thermally Stressed Fuel Fuel injected as a supercritical fluid (P>>Pcr, T<Tcr) Mixing and decomposition begin Fluid behavior must be modeled Accurate properties required Neat RP C µ, mpa-s 510 C T, C 18

19 Properties and Models at Extreme T/P Temperature (F) 800 Complementary Measurement Efforts Required property range Pressure (psia)

20 Combustion Evaluation Propellant Performance (vary fuel) Injector Stability (baseline fuel) Thermal Performance & Compatibility AFRL Single Element Hot-fire Facility GCSC Injector Element 20

21 Combustion Chemistry Models Physics-based: Hybrid approach decouples pyrolysis and oxidation ~20 µs Fuel pyrolysis ~700 µs Direct: Multiple experiments using real fuels Fragments oxidation Ignition 1410 K, 2.3 atm, 457 ppm n-c12h26/o2/ar, φ = 1 Compact: ~30 species, 2 orders of magnitude reduction for CFD use. 21

22 Fit-for-Purpose Quality: Lubricity & Wear Turbopump and Bearing Ref A RP-1 3D white light depth of HFRR ball end 22

23 Thermal Performance, Realistic Environment AFRL High Heat Flux Facility (HHFF) ~1800 F Fuel-Specific Coking Data from HHFF Cooling Channels SEM Image of Carbon Deposit 23

24 Thermal Stability as a Specification Test Compact Rapid Assessment of Fuel Thermal Integrity (CRAFTI) Parameter Test article mat l. Input power Wall temperature Backpressure Heated length Test duration Value Cu (C10100) 4500 W 1050±250 F 1,000 psi 4 in. 15 min. 24

25 Representative Results Temperature-programmed oxidation results in deposition fingerprint sensitive to small variations Test article pressure drop increase (15-min. run) is sensitive to withinspecification fuel variation 25

26 Transport & Handling - Oxygen Dramatic impact of dissolved O2 and polar species removal on cooling performance 26

27 Fuel Contamination GC GC TIC AIC, m/z detected sulfur 26: wt% aromatics, 5-8 ppm total S 39: 0.36 wt% aromatics, <1 ppm total S 27

28 Composition-Based Prediction Evaluate Fuel Performance with Minimal Testing these compounds drive deposit formation and ΔP 28

29 Future Direction Gov t/commercial relationships will clarify R&D activities Air Force buys launches from commercial suppliers Domestic RD-180 replacement outcome will guide focus Kerosene: Reusability may prompt continued work in some areas Thermal performance, component reliability, material compatibility, sensitivity to composition LCH4/LNG as rocket propellants will require similar research with shorter timelines Production, purity, properties, performance Use of high-fidelity models (and predictive tools) will increase, requiring complete and accurate datasets 29

30 Questions 30