turbomachinery improved fuel efficiency/reduced …...lead to more efficient engine designs, and...

National Aeronautics and Space Administration

www.nasa.gov

Turbomachinery Efficiency/EmissionsBreakout Summary from

NASA Aero-Propulsion Control Technology Roadmap Development Workshop

August 18-19, 2016, Cleveland, Ohio

Dennis [email protected]

&Joe Connolly

[email protected] Control and Autonomy Branch

NASA Glenn Research Center


www.nasa.gov

Turbomachinery Improved Fuel Efficiency & Reduced EmissionsNASA Aero-Propulsion Control Technology Roadmap Development WorkshopAugust 18, 2016 2


www.nasa.gov

Strategic Thrust 3: Ultra-EfficientCommercial Vehicles

• Large leaps in aircraft efficiency, coupled with reductions in noise and harmful emissions, are critical to the aviation community’s roadmap for achieving greatly improved environmental sustainability.

• ARMD will develop critical technologies to enable future generations of sub sonic fixed wing and vertical lift commercial aircraft that lessen environmental impacts while maintaining safety and improving operating economics.


www.nasa.gov


www.nasa.gov

Technology Metrics

• The following are metrics over the next three generations of subsonic transports for noise, emissions, and efficiency

• Propulsion plays a significant role in meeting the goals

• Note: individual technologies could be very design specific


www.nasa.gov

Gas Turbine Engine Research: Current Technical Challenges

• Propulsive Efficiency. – Low fan pressure ratios to reduce exhaust velocities and improve

propulsive efficiency. – Current NASA Work:

• Reduced duct losses, design optimization, boundary layer ingestion

• Thermodynamic Efficiency. – Enabling higher operating temperatures is a prerequisite to achieving

improvement in gas turbine engine thermodynamic efficiency.– Current NASA Work: Thrust 4: Alternative Fuels – Reduce Emissions

• Advanced materials, coatings for environmental protection

• Small Engine Cores. – Activities being pursue to improve overall aircraft efficiency result in

smaller core sizes. – Current NASA Work:

• Aerodynamic performance, secondary flow losses, life span of turbine


www.nasa.gov

Scope of Discussion

• Focus is on Advanced Ultra-Efficient Propulsion Control Technologies related to reductions in noise/emissions and improvements in efficiency

• Currently the majority of NASA propulsion controls work has focused on thermodynamic efficiency– Model-Based Engine Control and Dynamic Analysis allows

for higher pressure ratios and ensured safe operation– Distributed Engine Control weight reductions– Active Combustion Control emissions and weight reductions – Modeling and Simulations developing analysis tools

• There is some effort being done in small core tip clearance


www.nasa.gov

Aero-Propulsion Control Technology Roadmap Data Gathering Template

• Subject Area: Turbomachinery Efficiency/Reduced Emissions

• Thrust and Roadmap: Ultra-Efficient Commercial Vehicles – Advanced Ultra-Efficient Propulsion

• Goals: Reduced Noise (dB), Reduced Emissions (NOx), and Improved Efficiency (Fuel Burn)

• Top 2-5 Control Technology Challenges For each Control Technology Challenge:– Brief Description (What are we trying to do and why)– Relevance to Goals

• What is the Benefit – quantitative/qualitative– Technology Development Focus and Time Frame

• 5-10 years, 10-20 years, > 20 years


www.nasa.gov

Report Out from Breakout Session Discussion


www.nasa.gov

Participants in Turbomachinery Efficiency / Emissions Breakout Session held Aug 18, 2016

Turbomachinery Efficiency and Emissions SessionName OrganizationFirst Last

1 Kevin Driscoll Honeywell2 Shreeder Adibhatta GE Aviation3 Laura Frediani Sporian Microsystems4 Shawn Isham Parker Aerosapce5 Tracy Rice Parker Aerospace6 Rob Niebanck Triumph Engine Control System7 Conrad Golbov Rolls-Royce8 Milos Ilank United Technologies Research Center9 Jerry Sing United Technologies Research Center

10 Peter Uth NASA Intern11 Bobbie Hegwood Rolls-Royce12 Al Behbahani AFRL13 Ravi Rajamani drR2 Consulting14 Michael Hathaway NASA GRC


www.nasa.gov

High Level Technical Challenge Areas

• Improved Dynamic Modeling for Propulsion Controls

• Personalized Engine Control

• Integrated Flight and Propulsion Control

• Tighter Clearance Control

• Intelligent Management of Cooling Flow


www.nasa.gov

Improved Dynamic Modelingfor Propulsion Controls

• Description:– There is a critical need to provide a simulation environment that is suitable for the

development of models to assess advanced control concepts. This has primarily been done with only the modeling of the shaft inertias and gas path, but to realize all of the potential controls benefits this paradigm needs to change. The simulation environment required to assess future propulsion concepts will require thermal management systems, pumping systems, data management and propagation, diagnostic and prognostic integration, and a means to feed into or be compatible with design tools to illustrate benefits in the early engine design phase.

• Relevance to ARMD Goals:– Modeling and simulation is an enabling technology for all of the other technologies

discussed to realize the goals of reduction in noise, emissions and improvements in efficiency. In addition, the capability to consider performance/operability achievements possible with advanced control concepts early in the design phase can lead to more efficient engine designs, and also potentially avoid expensive fixes later in the design stage to meet safe operability requirements.

• Relevant Technologies:– Thermal Management, Fuel/Oil/Pumping Systems, Dynamic and Control

considerations in early design phase, Data Propagation delays, and Failure Modes


www.nasa.gov

Personalized Engine Control• Description:

– In order to keep pace with the increasing demands on engine performance, the control system must operate in a manner that exceeds the capabilities of current control architectures. By using an engine controller that can accommodate changing conditions as they occur, the engine can operate more efficiently. These changing conditions can be attributed to the variations in the flight profile or expected wear and deterioration that the engine will experience during its lifetime of use. This approach could also be used to handle minor faults in the engine if implemented with an on-board diagnostic system. This research will lead to a “personalized” control for each specific engine, which accommodates the actual condition of the engine to not only maintain more efficient operation throughout its lifetime but also increase its useful operating life while ensuring safety.

• Relevance to ARMD Thrust 3 Goals:– Efficiency Improvement is the primary benefit, with possible noise reduction given

additional variable geometries and prop/open rotor applications• Relevant Technologies:

– Margin Management, Engine Condition Assessment, Optimized Engine Control base on current condition, and High temperature sensors/actuators/electronics


www.nasa.gov

Integrated Flight and Propulsion Control (IFPC)• Description:

– As aircraft vehicle design becomes more integrated with the propulsion system design for advanced concepts, the integration of the control system is a logical next step. Communication between the flight control and propulsion control will enable coordinated transient maneuvers that will enable trajectory optimization. A personalized propulsion control architecture can be more effectively used by IFPC by its ability to provide greater mission profile awareness. During emergency scenarios that involve damage to the primary flight control surfaces this technology could also assist by providing greater stability to the vehicle through use of the propulsion system.

• Relevance to ARMD Thrust 3 Goals:– This technology could provide efficiency improvement through the fully

integrated vehicle control along with noise reductions during segments of the flight and greater safety. Innovative use of propulsion system as flight control effectors can potentially reduce airplane drag and weight.

• Relevant Technologies:– Knowledge of Aircraft/Engine Transients, Trajectory optimization – Mission

Profile Awareness, Wind milling - Engine Shutoff during Flight for fuel savings, and Knowledge of Flight Condition and Health Condition


www.nasa.gov

Tighter Turbine Tip Clearance Control• Description:

– Tighter clearance control is an attempt to improve engine efficiency and increase the on-wing life of commercial aircraft engines by manipulating both transient and steady state tip clearances during engine operation. Of particular concern is the pinch point for turbine tip clearance, a minimum clearance condition that can occur during takeoff or reburst. During these events, the rotor assembly expands rapidly, due to centrifugal forces and rapid heating of the turbine blades. At the same time, the surrounding case/shroud structure expands due to thermal effects, but at a much slower rate. The result is a rapid reduction in clearance. In time, the growth rate of the casing exceeds that of the rotor assembly and the clearance increases. To avoid rubbing at this condition, excess clearance must be designed into the turbine. In order to realize the full benefit of reduced clearances without damage to the engine, the clearance must be controlled throughout the flight profile.

• Relevance to ARMD Goals:– Improved efficiency would be the primary benefit, but also reductions in engine

exhaust gas temperature could lead to increased on-wing life. For current engines a 10 mil reduction in design clearance implies a 1% improvement in SFC. Benefits can be higher for advanced engines with small cores.

• Relevant Technologies:– Improved understanding and modeling of dynamics of tip clearance, higher

temperature sensors, and faster/light weight actuation


www.nasa.gov

Intelligent Management of Cooling Flow• Description:

– To improve the efficiency of turbofan engines, operation of the engine has gone to higher temperatures. This includes not only turbine components, but the compressors are operating at higher temperatures as well, putting a stress on the primary means to cool the hottest components of the engine. Therefore, new and innovative approaches will be necessary to achieve the next level of performance capability, similar to the improvements achieved with the introduction of turbine cooling. An intelligent management of the cooling flow is required. A tighter control of when the compressor bleed air is required and where the heat exchanger will transfer the heat from the bleed air to another source will be critical. Two potential heat sink sources are the fan bypass air and the engine fuel. This technology could significantly reduce cooling flow and turbine material temperatures, resulting in improved engine performance and life.

• Relevance to ARMD Goals:– Efficiency improvements are the primary benefits

• Relevant Technologies:– Cooled cooling, Reduced cooling based on condition awareness, Higher

temperature actuation to support modulated cooling, and Turbine exhaust flow management for recuperation of heat sources


www.nasa.gov

References

• Key Documents Located at: http://www.aeronautics.nasa.gov/strategic-plan.htm

– ARMD Strategic Plan

– ARMD Strategic Thrust 3: NASA Vertical Lift Strategic Direction

– ARMD Strategic Thrust 3: NASA Ultra-Efficient Commercial Vehicles Subsonic Transport

– Commercial Aircraft Propulsion and Energy Systems Research

http://www.aeronautics.nasa.gov/strategic-plan.htm