Document
National Aeronautics and Space Administration
Exploration of the Versatile
Electrically Augmented Turbine
Engine Gearbox Concept
Jonathan Kratz and Dennis Culley
NASA Glenn Research Center (GRC)
th
August 10 , 2021
www.nasa.gov 1 National Aeronautics and Space Administration
Motivation
More Electric Engine Operability Engines Control – Turbine Electrified A ircraft Electrified Energy P ropulsion (EAP) Management (TEEM) Hybrid Electric Propulsion Concepts (Ex. STARC - ABL) EM – Electric Machine Need to interface GB – Gearbox EMs of significant HPS – High Pressure Spool LPS – Low Pressure Spool
size with gas
DC – Direct Current AC – Alternating Current turbine engines How can EMs be synergistically interfaced with gas turbine, allowing the EMs to be better leveraged?
More Electrified Engine with Implementation of TEEM www.nasa.gov 2 National Aeronautics and Space Administration
Background
TEEM
Power Extraction
• Leverages EMs and energy storage to improve engine operability • Desire to extract large amounts of power from the engine to drive strategically placed propulsors Particularly during transients Reduces drag while producing thrust Alleviates constraints on the engine design to achieve better performance • Favors power extraction by can disproportionately favor one spool • Dedicated EM (DEM) approach: Each EM can only directly impact their respective spools Accelerations: Use the HPS EM to add power to the HPS Decelerations: Use the LPS EM to extract power from the LPS and use the HPS EM to apply any excess power to the HPS www.nasa.gov 3 National Aeronautics and Space Administration
VEATE Gearbox Description
Mechanical planetary gearboxes are not required but are assumed in this study • Essentially places a planetary gearbox between the HPS and LPS with a free spinning ring gear
• EMs are present to influence each
component of the gearbox EM1 influences the sun gear (HPS) Planetary Gearbox Anatomy EM2 influences the carrier (LPS) EM3 influences the ring gear • Clutches exist primarily for EM failure isolation Single Planetary (SP) Variant www.nasa.gov 4 National Aeronautics and Space Administration
VEATE Gearbox Model
• Enforces physical constraints of the gearbox system • Captures dynamics of all the gearbox components + the EMs + the engine spools • Is integrated with the Advanced Geared Turbofan 30,000 lbf (AGTF30) engine model r ω r ω 2 2 ω 𝑟 = ω 𝑟 1 1 2 2 Schematic of the AGTF30 engine with the VEATE gearbox (for illustration only) www.nasa.gov 5 National Aeronautics and Space Administration
Results: Power Effect
EM1 EM1 EM2 EM2 EM3 EM3 (+500 hp ) ( - 500 hp ) (+500 hp ) ( - 500 hp ) (+500 hp ) ( - 500 hp ) Δ Power HPS ~ + 500 hp ~ - 500 hp ~ +0 hp ~ +0 hp ~ - 377 hp ~ +389 hp Δ Power L PS ~ +0 hp ~ +0 hp ~ + 500 hp ~ - 500 hp ~ + 877 hp ~ - 889 hp • EM1 essentially only adds/extract power to/from the HPS (equivalent to the HPS EM in the dedicated EM approach) • EM2 essentially only adds/extract power to/from the LPS (equivalent to the HPS EM in the dedicated EM approach ) • EM3 influences mechanical power transfer between the spools while simultaneously applying or extracting power • Conclusions: ~0.75 hp is shift between the spools Enables a hybrid method of power management for every 1 hp Enables EMs that would be under utilized in a dedicated EM applied or extracted approach to be used to further improve operability with EM3 (particularly for TEEM) www.nasa.gov 6 National Aeronautics and Space Administration
Results: Power Effect
• It’s advantageous for LPC operability to … • It’s advantageous for HPC operability to … Extract power with EM3 Add power with EM1 Extract power with EM3 Add power with EM1 Extract power with EM2 • Conclusions: • Conclusions: EM3 can be used to assist EM1 to improve HPC operability during accels could reduce the size of EM1 to implement TEEM EM3 is more effective than EM2 at improving LPC operability during transients and can do the same task with Power Extraction with EM3 will help to offset the power applied by less power reduces overall power system size EM1 reduces the requirements for the energy storage system www.nasa.gov 7 National Aeronautics and Space Administration
Results: TEEM
• Similar control approach to the DEM option.
Difference are: Use of EM3 to supplement EM1 during accelerations EM1 EM1 Use of EM3 in place of the LPS EM during decelerations • Chop and burst scenario τ • Boosted operability in all cases EM3 EM3 • Potential to reduced EM sizes • Reduced peak power and energy storage use Acceleration Max Throttle Idle Time Deceleration Note: EM1 nominally extracts 350 hp to meet aircraft system power demands www.nasa.gov 8 National Aeronautics and Space Administration
Results: TEEM
• Considered a failure of the HPS EM/ EM1 Importance is related to the need to retain operability with a more aggressive design • DEM approach: No effective control effort during accels Limited control effort with the LPS EM during decels • VEATE approach: Uses EM3 during both accels and decels • The VEATE approach has superior operability with a modest 100 hp EM www.nasa.gov 9 National Aeronautics and Space Administration
Results: Power Extraction
• The VEATE gearbox can shift power between the spools • Makes more power available on one spool for power extraction Enables flexibility and power splits with similar performance and operability • More even power splits are possible Optimal split for the DEM approach is ~15%/85% (HPS EM/LPS EM) A split of 32%/48%/20% (EM1/EM2/EM3) is essentially equivalent Worst - case EM failure mode is better for the VEATE configuration www.nasa.gov 10 National Aeronautics and Space Administration
Conclusions
• The paper: provides a description of the Versatile Electrically Augmented Turbine Engine (VEATE) gearbox presents a modeling approach presents a simulation study of the impact of power injection/extraction through the VEATE gearbox • The VEATE gearbox provides a hybrid method for managing power on the spools of a gas turbine engine • There is evidence to suggest that the VEATE gearbox could: reduce the electrical power system size (particularly for Turbine Electrified Energy Management (TEEM)) introduce flexibility to power injection/extraction implementation improve system robustness and safety through inherent fail - safe features www.nasa.gov 11 National Aeronautics and Space Administration
Acknowledgements
• The authors would like to acknowledge the Transformational Tools & Technologies (TTT) project under the NASA Aeronautics Research Mission Directorate (ARMD) that has supported this work • Special thanks to Tim Krantz from NASA GRC for consulting with us about the concept
Contact Information
jonathan.kratz@nasa.gov dennis.e.culley@nasa.gov www.nasa.gov 12