National Aeronautics and Space Administration

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Dynamic Systems Analysis

4th Propulsion Control and Diagnostics Workshop

Ohio Aerospace Institute (OAI)

Cleveland, OH

December 11-12, 2013

1

Jeffrey Csank

NASA Glenn Research Center

National Aeronautics and Space Administration

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Team Members

• Jonathan Seidel, NASA Glenn Research Center/RTM

• Jeffrey Chin, NASA Glenn Research Center/RTM

• Alicia Zinnecker, N&R Engineering

• Georgia Institute of Technology

2

National Aeronautics and Space Administration

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Outline

• Preliminary Engine Design

• Systems Analysis

• Tool for Turbine Engine Closed-loop Transient

Analysis (TTECTrA)

• Dynamic Systems Analysis

• Conclusion

3

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Preliminary Engine Design

• Huge commitments are made

based on results

• A completely new engine is

relatively rare

• Most programs focus on

derivative engines

4

Weight

Performance

Scaling

Mission

Cycle

Configuration

Component

Design

Component

Test

Performance

Manufacture

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Systems Analysis

• Complex process that involves system-level

simulations to evaluate system-level

performance, weight, and cost (optimize system,

compromise component)

• Focus on steady-state design cycle performance

• Dynamic considerations

and issues are

incorporated through the

use of operating margins

– Stall margin

5

Corrected Flow (Wc)

Pre

ssu

re R

atio

(P

R)

National Aeronautics and Space Administration

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Tool for Turbine Engine Closed-loop

Transient Analysis (TTECTrA)

• Capable of automatically designing a controller

• Easily integrates with users engine model in

MATLAB/Simulink environment

• Provide an estimate of the closed-loop transient

performance/capability of a conceptual engine design

• Requirements:

– MATLAB®/Simulink® (Release R2012b or later)

• MATLAB® Version 8.0 (R2012b)

• Simulink® Version 8.0 (R2012b)

• Control Systems Toolbox® Version 9.4 (R2012b)

– Engine Model compatible with Simulink

– State space linear model in MATLAB

6

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TTECTrA Architecture

• TTECTrA software automatically designs:

– Set Point

– Set Point Controller

– Limit Controller

• Simulates different thrust profiles

7

User Model Set Point

Controller

Limit

Controller

Engine

Sensors

Selecto

r Lo

gic

Desired

Thrust

Set

Point

Actuator

Feedback

Error

Fuel

Flow Engine

Outputs Set Point

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TTECTrA - Set Point Function

• Flight condition (altitude, Mach, temperature)

• Define set point bounds and number of breakpoints

– Fuel flow

– Thrust

8

0 1 2 3 4 5

x 104

1000

1500

2000

2500

3000

3500

4000

4500

Close figure to accept setpointsLeave figure open and use GUI to recalculate

Corrected Thrust (lbf)

Con

tro

l V

ari

ab

le

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TTECTrA – Set Point Controller

• Bandwidth (Hz)

• Phase Margin

• Feedback filter (Hz)

• Throttle Filter (Hz)

9

-50

0

50

100

150

Mag

nitud

e (

dB

)

100

-180

-135

-90

-45

0

Pha

se

(d

eg

)

Bode Diagram

Frequency (rad/s)

Plant

Loop Gain

-10 0 10 20 30 40-10

-5

0

5

10Root Locus

Real Axis (seconds -1)

Imag

inary

Axi

s (

seco

nd

s-1)

0 2 4 60

0.5

1

1.5

Time, s

Con

trol

Vari

able

LM

Pre-Filter

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TTECTrA – Limit Controller

• Acceleration Minimum Surge Margin (HPC)

– Ncdot vs NcR25

• Deceleration Minimum Surge Margin (LPC)

– Wf/Ps3

10

7000 8000 9000 10000 11000 120000

200

400

600

800

1000

1200

1400

Corrected core speed (rpm)

Core

acce

lera

tion

(rp

m/s

ec)

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User Model

TTECTrA - Selector Logic / Actuator

• Selector Logic (Min/Max scheme)

– Min (Set Point, Acceleration)

– Max (Min, Deceleration)

• Actuators

– Currently only models fuel flow

– First order filter

11

Engine

Sensors

Selecto

r Lo

gic

Desired

Thrust Set Point

Actuator

Feedback

Error

Fuel

Flow Engine

Outputs

Set Point Set Point

Controller

Limit

Controller

Actuator

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Commercial Modular Aero Propulsion

System Simulator 40,000 (C-MAPSS40k)

• 40,000 Lb Thrust Class High Bypass Turbofan

Engine Simulation

• Matlab/Simulink Environment

12

• Publically

available

• Realistic controller

• Realistic surge

margin

calculations

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Burst and Chop Thrust Profile

• Idle (14% of max thrust) to Take-off thrust profile to test

the TTECTrA controller

• Compare the thrust response to the Federal Aviation

Administrations (FAA) Federal Aviation Regulation

(FAR) Part 33, Section 33.73(b)

13

0 10 20 30 40 500

2

4

6x 10

4

Time, s

Thru

st

0 10 20 30 40 501

1.5

2

Time, s

Con

tro

l V

ari

ab

le

Dmd

Fdbk

10 12 14 16 180

1

2

3

4

5x 10

4

Time, s

Thru

st

Dmd

Fdbk

95% Max

5 s

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Burst and Chop Thrust Profile

14

0 10 20 30 40 5010

20

30

40

50

HP

C S

M, %

Time, s

6000 8000 10000 12000-1000

-500

0

500

1000

1500

2000

Nc

dot

NcR25

0 10 20 30 40 5010

20

30

40

50

60

LP

C S

M, %

Time, s

0 10 20 30 40 500

0.002

0.004

0.006

0.008

0.01

0.012

Wf/P

s3

Time, s

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Engine Deterioration

15

0 20 40 6010

20

30

40

50

Time, s

HP

C S

M, %

0 20 40 6010

20

30

40

50

60

Time, s

LP

C S

M

0 20 40 601

1.2

1.4

1.6

1.8

Time, s

Con

tro

l V

ari

ab

le

0 20 40 600

1

2

3

4

5x 10

4

Time, s

Thru

st, lbf

New

EOL

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The Benefit of TTECTrA

Stack %

Uncertainty 11

Reynolds Number 2

Distortion 4

Tip Clearances 1.5

Deterioration 1.5

Random 2

Transient Allowance 12

Total 23

16

Do we have enough margin? Too much margin?

Corrected Flow (Wc)

Pre

ssu

re R

atio

(P

R)

Uncertainty

SA

DSA

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The Benefit of TTECTrA

• Combustor Stability

17

• Turbine life

• Low Pressure

Compressor

NcR25, rpm

Ps3

R, p

si

SA

DSA

Corrected Flow (Wc)

Pre

ssu

re R

atio

(P

R)

SA

DSA

Nc, rpm

T40

, R

SA

DSA

National Aeronautics and Space Administration

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Future Work

• NPSS Model in Simulink

– Georgia Institute of Technology

• Integrate TTECTrA with the NPSS Simulink model

– NASA/RHC

• Integrate TTECTrA/NPSS Simulink with a larger

systems analysis optimization algorithm

– NASA/RHC and NASA/RTM

18

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Conclusion

• Dynamic systems analysis:

– Enables engine transient performance to be accounted for in

the optimization of the engine design and early in the

preliminary design of turbine engines.

– Allows trading of overly conservative surge margin for better

performance through system redesign (or opline).

• Developed the Tool for Turbine Engine Closed-loop

Transient Analysis (TTECTrA)

– Capable of automatically designing a controller at a single

flight condition.

– Easily integrates with users engine model in

MATLAB/Simulink environment.

– Open source

19

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Questions?

20

Thank you