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Dynamometer Test Stand for Aircraft
Air Turbine Starter Testing
David Cardenas
Kevin Goldvarg
Carol Moreno
Department of Mechanical and Materials Engineering
Advisor:
Brian Reding, Ph.D.
Benjamin Boesl, Ph.D.
Introduction
Air turbine starters (ATS) performance tested after
repair/overhaul
Typical ATS test stand consists of flywheel to
simulate aircraft engines’ inertia
Turbine Controls, Inc. (TCI): Federal Aviation
Administration (FAA) approved repair station, desiring
to replace current ATS test stand
Desired feature: match wide range of inertia to
simulate various engines
Current test stand: limited by 2 flywheels
Purpose: investigate use of dynamometer or
absorber that can simulate inertia range for ATS
Impact TCI’s testing capacity expansion by
adapting to range of starters on the market
Problem Statement
Test system equipped for variable inertia simulation would
allow continuous load adjustments
Repeatability plays an important role for dynamometers
Results for torque and speed measurement expected to be same
within system tolerance level
Establishing repeatability is a complex aspect that must be
considered in design
Data acquisition, system control, and performance diagnosis
would allow data management, analyzing and graphing
required parameters
[1] J. S. Killedar, Dynamometer, Theory and Application to Engine Testing, Xlibris Corporation, 2012.
[2] National Instruments Corporation, "Achieve Flexibility in Your Automotive Dynamometer Applications," 07 August 2013. [Online]. Available:
http://www.ni.com/white-paper/2974/en/.
[3] DTec Devices, "Dynertia Users Manual: Inertia Dynamometer Control System," 2009. [Online]. Available:
http://dtec.net.au/Downloads/DYNertia%20Manual.pdf.
Main Design Components
Air Turbine Starter
Turns engine’s main compressor to provide airflow
As engine accelerates it will reach self-sustaining
speed and starter is disengaged
Dynamometer
Key device measuring rotating speed, torque,
power output
Absorption type: absorbs available
power doing work against
frictional resistance
Data Acquisition (DAQ)
Sampling signals measure real world physical
phenomenon and are converted into digital
numeric values
[1] U.S. Department of Transportation - Federal Aviation Administration, "Aviation Maintenance Technician Handbook - General," 03 April 2013.
[Online]. Available: https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook/.
[2] A. G. Ambekar, Mechanism and Machine Theory, New Delhi: Prentice-Hall of India Private Limited, 2007.
[4] W. Tong, "Motor Testing," in Mechanical Design of Electric Motors, CRC Press, 2014.
[3] National Instruments Corporation, "What is Data Acquisition," [Online]. Available: http://www.ni.com/data-acquisition/what-is/.
Design Selection for
Dynamometer Test Stand
Dynamometer Type
Hydraulic
Eddy current
Inertia
Hydraulic
Inertia
Low
High
Variable (adjustable)
Eddy Current
Cost
High
Very High
Low
Maintenance
High
Low
Low
Inertia
[1] Dyne Systems, Inc., "Dynamometer Comparison," [Online]. Available: http://www.dynesystems.com/what-is-a-dynamometer.htm
Design Parameters
Testing Procedure
Starter coupled to known polar moment of inertia [slug-ft2]
Air supplied to starter inlet at specified pressure and temperature
Conditions maintained constant throughout operating cycles
Brake held until inlet conditions stabilized
Brake released
Acceleration time measured 0 - cutoff RPM
Passing criterion
Acceleration time to cutoff speed must be within OEM-defined values
Hamilton Sundstrand, "Component Maintenance Manual: ATA 80-11-01,"
in Pneumatic Starter: PN 811050, 2010.
Preliminary Design Analysis
The following parameters must be identified for ATS to be tested
Maximum power and corresponding speed
𝑇)(2𝜋)(𝑁
𝑃𝑜𝑤𝑒𝑟ℎ𝑝 =
Minimum power and corresponding speed
33000
Maximum torque and corresponding speed
Minimum torque and corresponding speed
𝑃𝑜𝑤𝑒𝑟𝑘𝑊 =
𝑇)(2𝜋)(𝑁
60000
ATS manuals provide certain parameter specifications, including speed,
however power and torque are not know at corresponding speed
Using torque relationships, average torque can be found; not MAX or MIN
𝑇 = 𝐹𝑡 𝑙 = (𝐹𝑐𝑜𝑠𝛽)𝑙
𝑇 = 𝐼𝛼
[1] J. S. Killedar, Dynamometer, Theory and Application to Engine Testing, Xlibris Corporation, 2012.
[2] W. Tong, "Motor Testing," in Mechanical Design of Electric Motors, CRC Press, 2014.
Preliminary Design Analysis
TCI technicians have experience with main plot characteristics of an
ATS test curve
Common characteristics shared by ATS
To find out ATS peak torque and corresponding speed, ATS test will
be conducting using TCI’s current system to use as baseline for new
design
Design Selection
15 different manuals corresponding to sample ATS population used to extract
parameters
cutoff speed range: 3300 - 8750 RPM
Since eddy current dynamometer provides wider inertia range, it would be
most desirable design for TCI
Budget is additional restraint in design
As the most immediate solution, proposed design is:
a flywheel dynamometer that provides wide speed range through a variable
flywheel mechanism
Sample no.
Flywheel intertia
Max const α Min stall torque
Cutoff speed RPM t (s) ω (rad/s)
T inlet (F)
2
= I (slug-ft )
(rad/s2)
T = Iα (lbf-ft)
3.326
Smallest I
Largest I /
Largest
Cutoff RPM
Smallest
Cutoff RPM
69.04
21.4
FROM
0
0.0
0.0
44.5
148.0
…
3500
8.2
366.5
95.0
TO
FROM
7000
0
16.5
0.0
733.0
0.0
2.4
50.0
168.0
TO
8750
23.3
916.3
FROM
0
0.0
0.0
10.5
225.5
TO
3300
32.8
345.6
P inlet
(psig)
82.5
54
(+/(+/- 22.5 F)
1psia)
75
54
(+/- 2.7
(+/- 15 F)
psia)
60
33.6
(+/- 1
(+/- 10F)
psi)
Design Inspiration
Idea derived from system used in variable
weight dumbbells
One-piece dumbbell: handle bar fixedly
attached to a pair of end-weights at
opposing
Each end-weight may have 1 to 3 axiallyaligned, inwardly-opening, threaded
sockets
Each insert weight has a protruding,
threaded member
Insert weights are capable of attaching
to the socketed end-weights
A lock-socketed structure may provide
locking mechanism
V. K. Zarecky, "Variable Weight Dumbbell". United States Patent US5464379 A, 7 November 1995.
Scaled Prototype
Design Aspects
Project Timeline
Tasks & Responsibilities
TASK
1
2
3
4
5
6
7
8
9
10
11
12
DESCRIPTION
Preliminary meetings
Literature survey
Determine parameters
Analysis of parameters
Test current test stand
Consolidate design
Mechanical element selection
Model & prototype testing
Data acquisition
User manual & training
Engineering analysis
Report completion
TASK LEADER
All
Carol Moreno
Kevin Goldvarg
All
Kevin Goldvarg
Carol Moreno
David Cardenas
All
David Cardenas
All
All
All
DURATION
8 weeks
8 weeks
4 weeks
2 weeks
8 week
2 weeks
8 week
8 weeks
4 weeks
12 weeks
3 weeks
32 weeks
Elements of Global Design
Aviation regulations
Complies with FAA and EASA regulations
Transportation regulations
Must comply with international authorities
Oil-draining system
Environmental regulations
The device does not cause environmental damage
Plumbing system sealed
https://goglobal.fiu.edu/
Units & parameters
Test stand provides outputs according to country’s unit system
Usable with different countries’ input voltages
User manual
Instructions to setup tests
Engineering Standards
Electric motor testing standards
IEEE, IEC, ANSI/NEMA and EASA
Insulation resistance of rotating machine
Insulation testing
Methods that enable the user to determine efficiency and
energy losses
Methods that help to determine causes of temperature rise
Machine guarding standards
OSHA
Assure safe and healthful working conditions
Conclusion
Eddy current would be best solution
Complex
Expensive
Considerations
Cooling
Programming
Proposed solution: Variable flywheel dynamometer
Simpler
Inexpensive
Solve real problem
Engineering analysis focusing on vibrations
Multidisciplinary concepts
Teamwork
http://www.airliners.net
http://corporate.airfrance.com/
Questions