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Dynamometer Test Stand for Aircraft Air Turbine Starter Testing

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Presentation on theme: "Dynamometer Test Stand for Aircraft Air Turbine Starter Testing"— Presentation transcript:

1 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.

2 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

3 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 [Online]. Available: [3] DTec Devices, "Dynertia Users Manual: Inertia Dynamometer Control System," [Online]. Available:

4 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 [Online]. Available: [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:

5 Design Selection for Dynamometer Test Stand
Hydraulic Eddy Current Inertia [1] Dyne Systems, Inc., "Dynamometer Comparison," [Online]. Available:

6 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 ," in Pneumatic Starter: PN , 2010.

7 Preliminary Design Analysis
The following parameters must be identified for ATS to be tested Maximum power and corresponding speed Minimum power and corresponding speed Maximum torque and corresponding speed Minimum torque and corresponding speed 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 𝑃𝑜𝑤𝑒𝑟 ℎ𝑝 = 𝑇)(2𝜋)(𝑁 𝑃𝑜𝑤𝑒𝑟 𝑘𝑊 = 𝑇)(2𝜋)(𝑁 𝑇= 𝐹 𝑡 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.

8 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

9 Flywheel intertia = I (slug-ft2) Min stall torque T = Iα (lbf-ft)
Design Selection 15 different manuals corresponding to sample ATS population used to extract parameters cutoff speed range: 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 = I (slug-ft2) Cutoff speed RPM t (s) ω (rad/s) Max const α (rad/s2) Min stall torque T = Iα (lbf-ft) T inlet (F) P inlet (psig) Smallest I 3.326 FROM 0.0 44.5 148.0 82.5 54 3500 8.2 366.5 95.0 (+/ F) (+/- 1psia) TO 7000 16.5 733.0 50.0 Largest I / Largest Cutoff RPM 69.04 2.4 168.0 75 8750 23.3 916.3 (+/- 15 F) (+/- 2.7 psia) Smallest Cutoff RPM 21.4 10.5 225.5 60 33.6 3300 32.8 345.6 (+/- 10F) (+/- 1 psi)

10 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 axially- aligned, 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 US A, 7 November 1995.

11 Scaled Prototype

12 Design Aspects

13 Project Timeline

14 Tasks & Responsibilities

15 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 Units & parameters Test stand provides outputs according to country’s unit system Usable with different countries’ input voltages User manual Instructions to setup tests

16 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

17 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

18 Questions


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