Document
A Plan for Revolutionary Change in Gas Turbine Engine Control System Architecture Dennis Culley Controls and Dynamics Branch NASA Glenn Research Center The implementation of Distributed Engine Control technology on the gas turbine engine has been a vexing challenge for the controls comm unity. A successful implementation requires the resolution of multiple technical issues in areas such as network communications, power distribution, and system integration, but especially in the area of high temperature electronics. Impeding the achievem ent has been the lack of a clearly articulated message about the importance of the distributed control t echnology to future turbine engine system goals and objectives. To resolve these issues and bring the technology to fruition has, and will continue to require, a broad coalition of resources from government, industry, and academia. This presentation will describe the broad challenges facing the next generation of advanced control systems and the plan which is being put into action to successfully implem ent the technology on the next generation of gas turbine engine systems.
National Aeronautics and Space Administration
A Plan for Revolutionary Change in Gas Turbine
Engine Control System Architecture !
Dennis Culley Research Engineer Glenn Research Center, Controls & Dynamics Branch The Ohio State University April 18, 2011 Columbus, Ohio Fundamental Aeronautics Program www.nasa.gov Subsonic Fixed Wing Project 1
Gas Turbine Engine Control Technology !
FADEC Electronic/ Hydromechanical Capability Microprocessors & Software Hydromechanical Semiconductor Electronics Time Fundamental Aeronautics Program Subsonic Fixed Wing Project 2
Outline !
Why Do We Want/Need Distributed Engine Control? !
• System Drivers and Constraints !
• Stakeholder Perspectives !
What Do We Expect From Distributed Control? !
• Objectives for New Technology Development !
What is Preventing Us from Getting There? !
• Technical Challenges for Distributed Control !
What is the Go Forward Plan? !
• Vision !
• Development Plan !
Summary and Conclusions !
Fundamental Aeronautics Program Subsonic Fixed Wing Project 3 Why Do We Want/Need Distributed Engine Control? !
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System Drivers and Constraints !
Performance drivers and constraints which are compelling the next revolutionary step in engine control !
• The need for improved performance drives a need N EED for more control, implying more processing capability, additional volume, weight, and heat dissipation. !
P ERFORMANCE • The reality of more efficient engines ( smaller core) results in less available mounting envelope for C ONSTRAINTS controls and a hotter environment with less capacity to reject heat. !
Control systems typically account for 15 - 30% of engine system weight & cost and are the pacing item in engine system development !
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Commercial Control Implementation !
Fan Case Mounted - Air Cooled !
Fundamental Aeronautics Program Subsonic Fixed Wing Project 6 Public Release Photo Courtesy of Pratt & Whitney
Military Control Implementation !
Core Mounted - Fuel Cooled !
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System Drivers and Constraints !
P RESENT I NVESTMENT Affordability considerations !
• There is a cost for developing new technology !
A FFORDABILITY • There is a cost for not investing in new technology in terms of lost opportunities for improved performance !
F UTURE R ETURN O N I NVESTMENT Development of new technology does not guarantee adoption on production systems because customers are reluctant to buy more capability than they presently need !
Customers don ʼ t buy technology, they buy capability !
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Stakeholder Perspectives !
Progress in control system capability is predicated on advances in commercial microprocessor technology !
• There is virtually no viable alternative to the dependence on engine control capability and the high performance microprocessor !
There is virtually no influence on the commercial electronics market from the turbine engine controls community !
• Electronics obsolescence is a primary factor in control system cost !
Most control resources (money, manpower, time) are used to satisfy non-recurring engineering (NRE) issues related to the design, unplanned redesign, and upgrades to engine control systems !
• There is very little re-use of control hardware due to requirement flow down and regulations governing the qualification of systems !
A capability for Distributed Engine Control Architecture can have a major impact on the engine system performance and cost structure but the business case has not been made Fundamental Aeronautics Program Subsonic Fixed Wing Project 9 NASA Subsonic Transport System Level Metrics …. technology for dramatically improving noise, emissions, & performance !
SFW Approach - Conduct Discipline-based Foundational Research - Investigate Advanced Multi-Discipline Based Concepts and Technologies - Reduce Uncertainty in Multi-Disciplinary Design and Analysis Tools and Processes - Enable Major Changes in Engine Cycle/Airframe Configurations Fundamental Aeronautics Program Subsonic Fixed Wing Project 10 What Do We Expect from Distributed Engine Control? !
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Propulsion Controls – SFW Objectives !
Provide Critical Path Technology for Extremely Efficient Engines (UHB): !
• Combustion Control - lower emissions !
• Flow Control - improved aerothermodynamic efficiency, fuel burn !
• Stability Control - lower weight, field length !
Achieve Additional Control System Enhancements Supporting SFW Goals: !
• Directly reduce engine weight (e.g., reduce harness weight) !
• Improve propulsion responsiveness (e.g., local control loop closure) !
• Increase system performance (e.g., adaptive / intelligent control) !
Complement ARMD Objectives: !
• Improved vehicle performance by enabling highly integrated propulsion/ airframe control – e.g., asymmetric thrust balancing !
Enabled by " Transition to Modular, Distributed, and Embedded Functionality !
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Objectives for New Technology Development !
Retain access to the use of commercial microprocessor technologies to implement the complex control laws and the new engine technologies which will enable future engine system performance improvements. !
Address the disruptive issue of electronic component obsolescence. !
Develop system level technologies which enable reduction of NRE !
• To increase application of resources to value-added technologies !
• To increase the insertion of new technology by decreasing development costs !
• To decrease life-cycle costs by enabling reuse of components across platforms and from multiple suppliers !
The engine control system should never be the limiting factor in engine system performance Fundamental Aeronautics Program Subsonic Fixed Wing Project 13
Centralized Control Architecture !
Signal and power wire bundles with heavy sheathing Passive electrical sensors and actuators Environmentally for control protected and health commercial monitoring electronics Fundamental Aeronautics Program Subsonic Fixed Wing Project 14
Distributed Control Architecture !
TIM – Transducer Interface Module – embedded Fundamental Aeronautics Program Subsonic Fixed Wing Project 15 software specific to each smart device What is Preventing Us from Getting There? !
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Technical Challenges for Distributed Control !
Networked Communications !
• Enables the separation of control law processing from I/O !
• Over time will require much higher bandwidth primarily for diagnostics !
Power Distribution !
• I/O is the primary driver for unique power requirements !
• Lower weight will result with the distribution of common power and unique power developed in the end-element !
High Temperature Electronics !
• The fundamental technology which enables modularity of distributed components in the engine environment without incurring a weight penalty !
• Initial focus is on cost reduction with a long term strategy for improved functional capability !
Systems Integration !
• Optimal life-cycle cost reduction for the full engine system can only be realized with improved processes for the design, integration, and verification of modular components and systems !
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Technical Challenges for Distributed Control !
High Temperature Electronics !
Centralized: Commercially available electronics, limited to 125 C junction temperature, in a controlled environment. !
Distributed: Need to survive as embedded components on the engine without active cooling. !
• Are all the electronics technologies developed? If not, how will they be developed? !
• What are the requirements? !
• What will be the cost? !
• Is there more than one source? Are they reliable? Are they available for the long term? !
• What is the growth path? !
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Technical Challenges for Distributed Control !
Networked Communications !
Centralized: “Communication” is typically controlled by hardware in the FADEC. !
Distributed: Communications is a widely dispersed function outside of the FADEC. !
• What are the failure modes? !
• How does it affect engine stability? !
• Is there a common communication protocol that can be developed across industry? !
• What are the requirements? !
• How is it constrained by the high temperature electronics? !
• How will it evolve over time? !
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Technical Challenges for Distributed Control !
Power Distribution !
Centralized: Power distribution is system specific and housed inside the FADEC. !
Distributed: Power requirements cannot be precisely known !
• Is there a common power specification that can be developed across industry? !
• What is the envelope of requirements for future I/O? !
• How does distribution affect engine weight? !
• What are the thermal considerations? !
• How is reliability impacted? !
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Technical Challenges for Distributed Control !
Systems Integration !
Centralized: System is uniquely designed and certified. !
Distributed: Components must be individually certified. !
• What regulatory issues must be addressed/modified? !
• How will compliance be measured? !
• What tools need to be developed? !
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Technical Progress
! in Silicon Carbide (SiC) High Temperature Electronics !
• Demonstrated durability of discrete SiC JFET transistors. !
o – World record 10,000 hours operation at 500 C with excellent stability and operational characteristics !
• Fundamental Building Block of All Analog and Digital Circuits !
• Demonstrated capability for SiC integrated circuits. Interconnect structures are CRITICAL technology for high density packaging. !
– SiC JFET Analog Differential Amplifier, world record 5,000 hours operation o at 500 C !
• Fundamental Circuit for all Analog Functions !
o – SiC JFET Digital NOR Gate, world record 3,000 hours operation at 500 C !
• Fundamental Circuit for all Processor and Logic Functions !
• Multi-level interconnect structure milestone expected this year !
o – Capability for 1000 transistors on a common substrate at 500 C !
• Fundamental requirement for embedded smart devices !
Progress is directed at development of embedded smart sensors, actuators, and subsystem control capabilities " Fundamental Aeronautics Program Subsonic Fixed Wing Project 22 What is the Go Forward Plan? !
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Transition from Centralized Architecture !
T = 0 years • Electronic Control Unit Commercial Silicon Electronics Location Constrained by Harness Weight and Temperature • Analog Point-to-Point Connections from ECU to Control Elements • Unique Interfaces to each Control Element Fundamental Aeronautics Program Subsonic Fixed Wing Project 24
Transition to Core I/O Architecture
! … reduced fuel burn " T = 5 years Control Law Processor Compact, Commercial Silicon • Data Concentrator on Core • Digital Communications to Control Law Processor • Legacy Sensors and Actuators • Local Loop Closure Fundamental Aeronautics Program Subsonic Fixed Wing Project 25
Transition to Networked Control Architecture
! … reduced fuel burn, reduced NOx, reduced noise !
T = 10 years Control Law Processor Compact, Commercial Silicon • Compact Data Concentrator • Digital Communications to Control Law Processor • Networked Control Elements • >300 Celsius Electronics • Smart Sensors and Actuators • Embedded Subsystem Control Fundamental Aeronautics Program Subsonic Fixed Wing Project 26
Transition to Fully Distributed Architecture
! … reduced fuel burn, reduced NOx, reduced noise !
T = 15 years Control Law Processor Compact, Commercial Silicon • No Data Concentrator • Fully Networked control elements and Control Law Processor Wireless Capability • >300 Celsius Electronics • Fully Embedded Subsystem Control • Power Scavenging Technologies Fundamental Aeronautics Program Subsonic Fixed Wing Project 27
Development Plan for Distributed Control !
• The DEC barrier is primarily due to the cost of high temperature electronics and the lack of customer pull for their development !
• Successful development of DEC will require industry collaboration and a phased implementation to minimize cost and generate technology pull !
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Hardware-In-The-Loop !
A Hardware-In-The-Loop (HIL) test capability is proposed for the near time frame. The vision is to develop a Common Environment to solicit broad participation from industry/government/academia for the development of the next generation of control systems. !
• The concept of a common environment is based on the use of open standards for the interconnection of distributed control element components. The components themselves, and their embedded intellectual property, being unique. !
• HIL will enable investigations of distributed control system stability and performance. !
• HIL will enhance understanding of distributed controls with regard to system integration, verification, and certification. !
• HIL will be complimentary to and provide a means to verify simulation capability !
• A Common Environment HIL will be a focal point for future collaboration !
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Summary and Conclusions !
Without distributed control (constraints) – !
• Gas turbine engines are unlikely to achieve the full performance potential of improvements in other technology areas. !
• The lifecycle costs and weight of control systems will continue to increase relative to the engine system. !
With distributed control (enabler) – !
• New control-based technologies can be introduced into the engine system which further improve performance and lower cost. !
Distributed Control requires advances in power distribution, network communications, systems integration but especially high temperature electronics to be successful. !
The implementation roadmap is designed to cooperatively leverage government and industry efforts to achieve an initial implementation success and assumes increasing customer pull and continued stakeholder collaboration will enable full technology maturation. !
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Acknowledgements !
Support for this work is provided by the NASA Fundamental Aeronautics Program, Subsonic Fixed Wing Project !
The Distributed Engine Control Working Group, a consortium of US government and turbine engine industry representatives, has been a major contributor to this effort !
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