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