Presented to: Mech Aero 2015 (San Francisco, CA) Unmanned Aircraft System (UAS) Engine Research at U.S. Army Research Laboratory Dr. Mike Kweon Engines Research Team Lead VTD-Propulsion Division U.S. Army Research Laboratory October 7, 2015 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Why Unmanned Systems? Multiple advantages to manned systems Enhance situational awareness ISR Eyes of the Army Reduce human workload Improve mission performance Persistence, versatility, survivability Ideal for dull, dirty or dangerous missions Minimize overall risk to human life Reduce cost 2
UAS Applications Selected UAS Application Areas rescue filming agriculture Fire fighting Border control military 3
U.S. DoD UAS Inventory Dramatic increase over the last 15 years 8500 8000 Number of UAS [units] 7500 7000 6500 6000 5500 UAS Usage (2015) 0.4% 1.3% 4.2% 94.1% ARMY AF NAVY MC Army: 48 (2001) >7500 (2015) 5000 2011 2012 2013 2014 2015 2016 2017 Fiscal Year (Ref: DoD Report to Congress, 2012) 4
BUDGET [$M] UAS Presidential Budget (PB14) Decreased budget trend for DoD UAS RDTE but global UAS spending may double over the next decade (prediction) $2,500.00 2014 2015 2016 2017 2018 $2,000.00 $1,500.00 $1,000.00 $500.00 $- RDTE PROCUREMENT OM CATEGORY RDTE: Research, Development, Test, and Evaluation OM: Operations & Maintenance (Ref: Unmanned Systems Integrated Roadmap FY2013-2038, 14-S-0553) 5
Altitude [ft] Current Major Army UAS Increased payload more power MQ-1C 29,000 20,000 15,000 100-500 RQ-11B Group 1 (0-20 lbs) ISR Group 3 (<1320 lbs) ISR/RSTA, C3, FP Group 3 (<1320 lbs) ISR/RSTA, C3, Log, PS/TCS, FP 0.208L 28 kw rotary engine 104-127 mph 25.3 kg total payload 170 kg MTOW Electric motor; 30-60 mph, 1.9 kg total weight 1-1.5 RQ-7B MQ-5B Group 4 (>1320 lbs) ISR/RSTA, C3, Log, PS/TCS, FP 82 kw 2x0.8L diesel engine 69/92-138 mph 227 kg total payload 884.5 kg MTOW 119 kw 2L diesel engine 81-155 mph 760 kg total payload 1633 kg MTOW DoD designation R: Reconnaissance aircraft M: Multi-role Q: Remotely piloted aircraft system #: series number of the remotely piloted aircraft systems 6 21 30 Endurance [hrs] More missions 6
UAS Future for the Army Manned-UnManned Teaming (MUM-T) Technologies: Merge air, ground, sea unmanned systems with unmanned and manned systems Parameter Unit Apache AH-64E Gray Eagle Shadow Speed [mph] 165-177 81-155 104-127 Range [mi] 295 249 68 Endurance [hrs] ~3 30 6 Max altitude [ft] 21,000 29,000 15,000 Teaming among Apache, Gray Eagle, and Shadow Needs: Runway independent vertical takeoff Easy to takeoff Longer endurance Equivalent speed to Apache Increased mobility with small more agile manned-unmanned systems Needs: Interoperability UAV Swarms 7
Problems Mechanical failures & Operator mistakes Hit Crashes What should we do? 8
Areas for Improvements in Propulsion & Power Reliability - #1 priority - survivability Reliable components / software Increased power - #2 priority - survivability Payload is being increased for electronic devices and weapons Longer endurance Needs to perform more missions Multi heavy fuel capability Reduce the logistic cost Engine technologies to operate on heavy fuels: F-24, JP-8, alt Jet fuels Reduced signature - susceptibility IR, noise, and smoke Signature detection and reduction technologies Increased speed To team with faster rotorcrafts such as Apache Must be affordable!!! 9
Small Engine Research Facilities DoD Unique Small Engine Altitude Research Facility Fuel Spray Atomization Vaporization Mixing Combustion Power/Efficiency Small Engine Comb Res Lab Power: up to 302 hp Torque: up to 535 Nm Speed: up to 11,000 rpm Small Engine Altitude Res Facility Thermal Optical Single-cylinder research engine Opposed piston engine Altitude: up to 25,000 ft (30,000 ft) Temp: -40 to 130 F Power: 1 to 250 hp Speed: up to 30,000 rpm 10
Multi Heavy Fuel Capability Combustion Dependence on Fuel Properties Heat release rate [J/cad] 70 60 50 40 30 20 10 Cool flame Heat release rate: 3200 rpm/20% Premixed phase Mixing controlled phase CN30 CN35 CN40 CN45 CN50 CN55 Heat release rate [J/cad] 140 120 100 80 60 40 20 Heat release rate: 3200 rpm/40% Premixed phase Pre injection combustion Mixing controlled phase CN30 CN35 CN40 CN45 CN50 CN55 0 0-10 -30-20 -10 0 10 20 30 40 50 CAD [ atdc] -20-30 -20-10 0 10 20 30 40 50 CAD [ atdc] Extremely sensitive to fuel cetane number Insensitive to engine power except for the low CN fuels Knocking, noise, detonation reliability concerns 11
Real Engine T & P at Fuel Injection Pressures & Temperatures at Fuel Injections 1000 950 pre injection main injection In-cylinder temperature [K] 900 850 800 750 700 650 600 10 bar/580 K MAT cut at 40 C 550 500 0 10 20 30 40 50 60 70 80 In-cylinder pressure [bar] Pre injection: between 10 and 17 bar and between 580 and 670 K Needs to prevent misfire and achieve optimal combustion at high altitudes 12
Spray Combustion Research Facility DoD Unique High-Pressure High-Temperature Chamber Fuel Spray Atomization Vaporization Mixing Combustion Power/Efficiency P: amb to 150 bar T: 300 to 1000 K O2 content: 0-21% 13
T & P at Fuel Injection Measure Spray, Ignition and Combustion Processes In-cylinder temperature [K] 1000 950 900 850 800 750 700 650 600 (1.00) (1.05) (1.11) (1.18) (1.25) (1.33) (1.43) (1.54) (1.67) High Temp Mid Temp Spray A CRC (SNL) No visible combustion ARL ARL_new SNL 550 (1.82) Low Temp 500 0 10 20 30 40 50 60 70 80 90 100 In-cylinder pressure [bar] 14
ID vs. Pressure Ignition Delay Dependence on Pressure & Fuel Property 3 A-2 C-1 2.5 15k ft 5k ft 25k ft 10k ft Sea level T=900K Ignition delay [ms] 2 1.5 Higher altitudes 1 0.5 2 4 6 8 10 12 14 16 Pressure [MPa] Exponentially increased ID with decreasing pressure Lower CN fuel increases ID at lower pressures increased CN impact at high altitudes 15
CD vs. Pressure Combustion Duration Dependence on Pressure & Fuel Property 3.3 3.2 15k ft 5k ft Combustion duration [ms] 3.1 3 2.9 2.8 2.7 2.6 25k ft 10k ft Sea level Higher altitudes T=900K 2.5 A-2 C-1 2 4 6 8 10 12 14 16 Pressure [MPa] CD gets shorter at lower pressure and CN potentially higher EGT 16
Conclusions U.S. Army UAS dramatically increased over the last 15 years U.S. Army owns about 94% of all UAS aircrafts within the U.S. DoD Overall DoD RDTE budget is decreasing but the overall spending will gradually increase. Global UAS spending is predicted to dramatically increase over the next decade Current highest priorities include reliability, increased power, and longer endurance within affordability Uncontrolled fuel property poses significant reliability concerns Needs for optimal engine design and calibration for high altitude operation 17
Acknowledgements ARL-VTP Michael T. Szedlmayer and Michael J. Tess AMRDEC AED Joseph Gibson, Ross H. Armstrong, Christopher A. Lindsey, Rik D. Meininger, Newman B. Jackson, and Bernard Acker PM UAS Andrew V. Giddings, William G. Barnwell, Thomas P. Durgin, and Daniel F. Dittenber General Atomics Aeronautical Systems Inc Donald Sauder 18
Thank You!