Document
www.nasa.gov
Alicia Zinnecker
N&R Engineering
Cleveland, OH
July 28-30, 2014
Propulsion Systems Session
2014 Propulsion and Energy Forum
Dynamic Systems Analysis
Jeffrey Csank
Application of the Tool for Turbine Engine
Engineering, Sensing, Measuring and Distributed Technologies for
Closed-loop Transient Analysis (TTECTrA) for
NASA Glenn Research Center
National Aeronautics and Space Administration www.nasa.gov
Thanks to the NASA Fixed Wing Project Systems Analysis & Integration For funding this work
Acknowledgements
National Aeronautics and Space Administration www.nasa.gov
Outline
Engine Design Process Dynamic Systems Analysis Concept Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) Application with TTECTrA Summary Future Work
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National Aeronautics and Space Administration www.nasa.gov Assess transient performance, etc.
Define engine constraints (component efficiencies, speeds, temperatures, and operating margins) Optimize the system (Airframe and Engine) Configure the engine’s components to meet the requirements Build more detailed physics based models
Engine Design Process
Systems Analysis
National Aeronautics and Space Administration Surge Margin
11% 12% 23%
www.nasa.gov Target Operating Line ine L
Corrected Mass Flow Rate
Surge Line Lines of Constant Rotational Speed
Uncertainty Allowance Transient Allowance Total
Pressure Ratio
mechanical imperfections, inlet distortion, engine degradation, etc. occurs while transitioning from one point to another
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Most efficient operation while meeting design constraint. Uncertainty Allowance Transient Allowance
Compressor Surge Margin Constraint
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Based on previous experience, designs, and generic rules of thumb Target Operating Line Accounts for two different types of reductions
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Surge Margin Constraint
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National Aeronautics and Space Administration www.nasa.gov Performance Requirement
Time
Thrust
Transient Allowance Uncertainty Allowance Target Operating Line
Dynamic Systems Analysis Concept
Uncertainty allowance is greater than needed / Poor performance Uncertainty allowance is less than required / Good performance
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Decrease Transient Allowance / Increase Uncertainty Allowance Increase Transient Allowance / Decrease Uncertainty Allowance
Corrected Mass Flow Rate
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Better defining margins/constraints may allow a more efficient design while still meeting performance requirements
Pressure Ratio
National Aeronautics and Space Administration www.nasa.gov http://www.swri.org/npss/ has to be accounted for.
i
l
Dynamic Systems Analysis Concept
closed loop controller t
Systems analysis is performed using steady-state data usually generated from NPSS. To more accurately define the margins, the impact of the
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National Aeronautics and Space Administration www.nasa.gov
)
losed-loop
C
TTECTrA
ngine
E
nalysis (
A
urbine
T
ansient
Tr
ool for
T
MATLAB/Simulink (Release R2012b or later) with Control Systems Toolbox® Version 9.4 (R2012b) Engine model compatible with Simulink State space model
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Provide an estimate of the closed-loop transient performance/capability of a conceptual engine design. Capable of automatically designing a controller for transient operation (subset of full controller). Easily integrates with a users engine model in the MATLAB®/Simulink® Environment. Requirements:
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National Aeronautics and Space Administration www.nasa.gov Actuator Max Feedback RU Limiter Limiter Ps3Min Min Nf Nc Limiter Limiter Limiter Accel Limiter Ps30 Max Set Point Controller Error
TTECTrA Control Architecture
σ
Control Variable Set Point Desired Thrust National Aeronautics and Space Administration 12000 11000 10000 www.nasa.gov Corrected core speed 200 400 600 800 1000 1200 1400 1600 1800 Core acceleration limit
Limit Controller
TTECTrA
40 ) LM Pre-Filter -1 4.5 x 10 Root Locus Time, s Real Axis (seconds 3.5 1 -20 0 10 20 -20 -10 0 1 Imaginary Axis (seconds ) 0.5 1.5 -1 2.5 Control Variable Corrected Thrust 1.5 Close figure to accept setpoints Plant Loop Gain Leave figure open and use GUI to recalculate 0.5 Bode Diagram Frequency (rad/s) 1000 1500 2000 2500 3000 3500 4000 4500 Control Variable 0 0 -50 -90 -45 100 150 -180 -135 Magnitude (dB) Phase (deg) National Aeronautics and Space Administration
Set Point Set Point Controller
www.nasa.gov
Commercial Modular Aero-Propulsion
System Simulation 40,000 (C-MAPSS40k)
40,000 lb Thrust class high bypass turbofan engine simulation MATLAB/Simulink environment Publicly available to US Citizens Realistic controller Realistic surge margin calculations
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National Aeronautics and Space Administration www.nasa.gov 2.5 x 10 CMAPSS40k Engine A 1.5 Corrected Thrust, lbf -5 Corrected Flow, lbf x 10 7 8 6.8 7.2 7.4 7.6 7.8 TSFC, lbf/(lb/s) 1 2 3 1.5 2.5 3.5 Pressure Ratio CMAPSS40k Engine A
TTECTrA Application
Corrected Flow, lbf 0 5 10 15 20 Pressure Ratio
Compare CMAPSS40k to a Scaled version (Engine A) which is more fuel efficient (Lower TSFC)
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National Aeronautics and Space Administration www.nasa.gov
40k lbf
11%
15%
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Value 10 Hz 10 Hz
45 deg
1.75 Hz
2.3
Parameter Thrust Range Bandwidth Phase Margin Filter Bandwidth Pre-Filter Bandwidth Acceleration Limit Deceleration Limit TTECTrA Inputs
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TTECTrA Application
acceleration time
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Thrust HPC Surge Margin minimum surge margin LPC Surge Margin minimum surge margin
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Design controllers using TTECTrA and same inputs Simulate a burst and chop thrust profile and observe the following outputs:
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National Aeronautics and Space Administration 45 45 45 40 40 40 www.nasa.gov CMAPSS40k Engine A 35 35 35 30 30 30 25 25 25 Time, s Time, s Time, s 20 20 20 15 15 15 10 10 10 x 10 5 5 5 0 2 4 6 0 0 Thrust, lbf 20 40 60 20 40 60 HPC SM, % LPC SM, %
Engine Design Comparison
Engine A has a slower response time than CMAPSS40k Engine A has a lower surge margin in steady- state Both have same minimum surge margin due to acceleration limiters being designed for same minimum surge margin National Aeronautics and Space Administration 45 45 45 40 40 40 www.nasa.gov CMAPSS40k Engine A Engine B 35 35 35 30 30 30 25 25 25 Time, s Time, s Time, s 20 20 20 15 15 15 10 10 10 x 10 5 5 5 0 2 4 6 0 0 20 40 60 50 Thrust, lbf HPC SM, % 100 LPC SM, % C S %
Engine Design Comparison
Redesign acceleration limiter to have lower minimum HPC surge margin (Engine B)
Lower minimum surge margin increase performance Modify the acceleration limiter for various surge margin limits and observe response time.
National Aeronautics and Space Administration Original SM17 SM14 SM11 SM8 SM6 SM4 SM2 www.nasa.gov Time,s x 10 1 2 3 4 0.5 1.5 2.5 3.5 4.5 Thrust,lbf
CMAPSS40k
Engine Design Comparison
Corrected Flow, lb/s Original SM17 SM14 SM11 SM8 SM6 SM4 SM2 4 6 8 10 12 14 16 Pressure Ratio National Aeronautics and Space Administration www.nasa.gov Minimum Surge Margin, % CMAPSS40k Engine A 2 3 4 5 6 7 8 9 Accel Time, s
Evaluation Tool
Transient performance requirement (5 seconds) Initial surge margin requirement (11%) Reduce surge margin requirement (8%) Identify overly conservative margin and perhaps reduce the target operating line by this extra margin.
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National Aeronautics and Space Administration www.nasa.gov
Summary
Better defining the transient operation of the engine early in the design phase may allow moving the operating line and impact the design by increasing efficiency Provides an estimate of the transient operation Compares performance (acceleration time) and operability (surge margin) Capable of identifying designs that are capable of meeting transient performance requirements. Identify overly conservative margin and perhaps reduce the target operating line by this extra margin.
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Dynamic Systems Analysis Goal Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) Evaluation Tool
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National Aeronautics and Space Administration www.nasa.gov
TTECTrA Status
https://github.com/nasa/TTECTrA/releases
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TTECTrA is publicly available
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National Aeronautics and Space Administration www.nasa.gov
Future Work
Developing an automated version of TTECTrA and plan to release early 2015 Developing version of TTECTrA for integration with an NPSS through a Simulink S-function Developing process for incorporating dynamic systems analysis with current systems analysis method Investigate other engine architectures
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National Aeronautics and Space Administration www.nasa.gov
Thank you
Questions?
National Aeronautics and Space Administration