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Jet engines’ test cells – Considerations in selecting level of automation

Jet engines’ test cells – Considerations in selecting level of automation. Presentation for: 10 th Israeli Symposium on Jet Engines and gas turbines. Presented by: Ze’ev Ben-Porath. November 2011. Considering automation levels Introduction.

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Jet engines’ test cells – Considerations in selecting level of automation

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  1. Jet engines’ test cells –Considerations in selecting level of automation Presentation for: 10th Israeli Symposium on Jet Engines and gas turbines Presented by: Ze’ev Ben-Porath November 2011 721004011

  2. Considering automation levelsIntroduction The company: Magnus Engineering inc.Specializes in the construction and maintenance of computerized test cells since 1991.- Please visit www.magnus-eng.com The product: MCTC - Magnus Computerized Test Cell* Integrating all aspects of test cell operation.* Installed in more than 35 test cells worldwide.* Currently implemented for over 60 engine types.* 95% “generic”.* External test cell definition - User updateable. * Supports all levels of automation. 721004011

  3. Considering automation levelsIntroduction (2) The test cell: F100-PW-229 Post-Production at WZL4* Built by P&W for Polish AF.* International bid won by ATEC+Magnus.* ATEC – main contractor. Construction, Adapter, Fuel System (+heating), etc. * Magnus – subcontractor. Data acquisition, System control, Computer system. * ~4-hour test process as defined by TIS. * 95% automatic run. 721004011

  4. Considering automation levelsAutomation Levels Definition (1) Level 1: No Automation* No central computer system.* Independent displays of subsystems’ data.* Manual recording (and processing) of data. * Very common for jet engine test cells in 1980-90’s. 721004011

  5. Considering automation levelsAutomation Levels Definition (2) Level 2: Centralized Data Acquisition* Central computer system, acquiring data directly or digitally from all other subsystems.Benefits:* Automated data processing (e.g.: filtering, average, maximum, minimum, tare-value computation).* Computation of derived parameters and states. (e.g. corrected performance data, steady state). * Alarms for simple and complex limits.* Data recording and playback/analysis capabilities. 721004011

  6. Considering automation levelsAutomation Levels Definition (3) Level 3: Test procedure Tracking* Central computer system tracks the testing process, instructs operator and performs the required engine data validation.Benefits:* Ensures adherence to specified test procedure.* Eliminates possible human errors in evaluating results. * Automated computation of process-related data. (e.g. maximum vibration points, transient timing etc.).* Significant savings in time and fuel. 721004011

  7. Considering automation levelsAutomation Levels Definition (3.1) Level 3 example: Vibration sweep for F110-GE-100Task Definition:(3) Advance throttle slowly, taking 2 minutes to reach intermediate, and stabilize engine for 30 seconds.(4) Retard throttle slowly, taking 2 minutes to decelerate to idle.(5) Record peak vibration and rpm at which peak occurred…In the following demo, 4 Vibration values are tracked, and peak rpm values recorded separately for idle->MIL, MIL dwell and MIL->idle sections. (display rate is 10 times faster than actual rate). Actual times: Idle->MIL: 2min, 21sec MIL dwell: 48sec MIL->idle: 1min, 48sec Vibration sweep demo: Total: ~5 minutes 721004011

  8. Considering automation levelsAutomation Levels Definition (4) Level 4: Automated Test Execution* Central computer system executes all (or most) of the test procedure by sending appropriate commands to the engine and/or to external subsystems (PLC, Throttle, Dynamometer etc.). Benefits:* Exact execution of complex test procedures. * Improved safety due to fast response to dangerous situations. * Accurate repeatability of tests (facilitate research/development).* Savings in time and fuel. 721004011

  9. Considering automation levelsAutomation Levels Definition (4.1) Level 4 example: Safety event in a Volvo (bus) engineEvent Description:(1) Water pump breaks down.(2) Vapors rising into cooling water tank cause increased pressure.(3) System detects abnormal cooling water level (measured as pressure). (5) Audio and Visual Alarms activated.(4) Smooth return to Idle/Manual mode is automatically executed. Safety Event demo: 721004011

  10. Considering automation levelsAutomation Level Driving factors (5.1) Driving Factor A: Test Accuracy Requirements* Requirements for very accurate execution of complex test sequences may necessitate level 4 automation.* Jet engine testing requirements (as we encountered) are sometimes border line cases:- Measuring transient of ~2 seconds (TIS).- Break-In procedures (e.g. a sequence of 2,5,2,5… seconds transients to intermediate PLA positions).- Vibration sweeps requiring smooth (constant rate) movement of PLA. 721004011

  11. Considering automation levelsAutomation Level Driving factors (5.1.1) Example: Manual vs. Automatic Vibration sweepThe Task: (F100-PW-229, Core Run-In)“Perform slow acceleration (20-30 seconds) [from 56º] to MIL” Relatively good coverage of the range, but in ~45 seconds. 721004011

  12. Considering automation levelsAutomation Level Driving factors (5.1.2) Example: Manual vs. Automatic Vibration sweepThe Task: (F100-PW-229, Core Run-In)“Perform slow acceleration (20-30 seconds) [from 77º] to 91º” Same operator, 45 minutes later (tired and impatient?):Up to MIL in 2 jumps. ~20 seconds to 91º. 721004011

  13. Considering automation levelsAutomation Level Driving factors (5.1.3) Example: Manual vs. Automatic Vibration sweepThe Task: (F100-PW-229, Core Run-In)“Perform slow acceleration (20-30 seconds) [from 77º] to Min Augmentation” Spikes due to problems in the Electric Throttle. 721004011

  14. Considering automation levelsAutomation Level Driving factors (5.2) Driving Factor B: Test ComplexityComplexity: Number of steps, rate of changes, number of different output commands, requirements to synchronize external subsystems (e.g. move throttle while changing load generated by a dynamometer – T700 testing).* Very Simple tests: Level 2 sufficient (e.g. run engine 30 minutes, measure oil consumption).* Intermediate complexity: Level 3 or 4 (depending on other factors). Most Jet engines.* High complexity: Level 4 recommended (if not too hard to implement!). e.g. 8000->3500->7400 ->3500rpm, ~500 changes, 80 hours break-in run for UAV engine. Optimized using dynamic PLA-RPM mapping function. 721004011

  15. Considering automation levelsAutomation Level Driving factors (5.3) Driving Factor C: Work LoadThe work load determines the economic viability of full automation (level 4). * low work load: Level 2 or 3.* medium work load (typical for Jet engines): border line case for investing in level 4 automation. Exact calculation required.* High work load: indication for level 4 automation. (Unless the complexity is very, very low!). Sample case: Egged bus-engines test cell. 721004011

  16. Considering automation levelsAutomation Level Driving factors (5.4) Driving Factor D: ”Cost of Error”A very high cost of error in the test procedure (combined with medium or high test complexity) may dictate full automation,even in cases of low work load. 721004011

  17. Considering automation levelsEstimating expected time savings (1) A method to estimate expected savings in test time by upgrading an existing test cell to a higher automation level.1. Identify a significant section of the test procedure where all steps are “well-defined” duration-wise.Well defined: - Stabilize 5 seconds at 91º. - Perform slow (20 to 30 seconds) to MIL.Undefined: remain at IDLE until main oil temperature reaches 100°F.2. locate a set of executed tests (for said section) which were executed successfully, continuously and accurately (avoid cases where test steps were shorter than the minimum time specified by the test instructions). 721004011

  18. Considering automation levelsEstimating expected time savings (2) 3. Compute:Tmin = theoretical minimum time to complete the test section.Aavg = Average actual time to complete the test section.Amin = Minimum actual time to complete the section.4. Upper limit of saved run time: Aavg - Tmin 5. Minimum expected saved run time : Aavg – Amin.6. If you have access to a test cell that runs the same tests at the target automation level – extract from that test cell data:Eavg = average execution time at target automation level.7. Actual expected saved run time : Aavg – Eavg. 721004011

  19. Considering automation levelsEstimating expected time savings (3) Sample Calculation:- Section C and D of the F100-PW-229 acceptance test (C1 to D11).- Data from 12 runs from 2 different test cells.- Test cells at automation level 3, considering upgrade to level 4.Tmin = 23 minutes, 5 seconds (1,385 seconds).Amin = 24 minutes, 44 seconds (1,484 seconds).Aavg = 25 minutes, 51 seconds (1,551 seconds).Amax = 27 minutes, 48 seconds (1,668 seconds. 33m case discarded) lower limit on saved time: Aavg–Amin = 67 seconds ~4.3%(of Aavg)upper limit on saved time: Aavg–Tmin = 166 seconds ~ 10.7% Note: block of 15 minutes at IDLE observed at beginning of all runs. Means the expected fuel saving will be much more than 11%. 721004011

  20. Considering automation levelsEstimating expected time savings (4) • Another Sample Calculation: • - Steps 36-99 of the F100-PW-229 Core Run-IN. • Data from 5 runs from 1 test cell.- - Test cell at automation level 3, considering upgrade to level 4.Tmin = 1,901 seconds.Amin = 2,051 seconds.Aavg = 2,077 seconds.Amax = 2,124 seconds. lower limit on saved time: Aavg–Amin = 26 seconds ~1.3%(of Aavg) • upper limit on saved time: Aavg–Tmin = 176 seconds ~ 8.5% 721004011

  21. Considering automation levelsEstimating expected fuel savings (1) The expected fuel saving (%) is larger than the expected time savingssince the periods at high power settings are much shorter than the periods at IDLE.Given an existing level 3 test cell, it is possible to estimate the fuel savings by an upgrade to level 4, by precise analysis of recorded test runs:1. Section 1 and 2 as before.2. Compute the theoretical time to stay at each PLA position (range).3. Extract scan data for the selected test sections including PLA setting and fuel Flow (MCTC-4 scans/sec).4. Compute actual time and average fuel flow at each PLA position.5. Compute total time and total fuel flow at each PLA position and compare to theoretical time. 721004011

  22. Considering automation levelsEstimating expected fuel savings (2) Sample calculation for:- Steps 36-83 of the F100-PW-229 Core Run-IN. - From a manual run at a level 3 test cell. 721004011

  23. Considering automation levelsEstimating expected fuel savings (3) Sample calculation for:- Steps 36-83 of the F100-PW-229 Core Run-IN.- From an Automatic run at the WZL4 test cell. 721004011

  24. Considering automation levelsActual / Expected results Based on our actual experience and the above discussions:- Upgrade from level 2 to level 3 has resulted in 30-50% save in run time and fuel consumption (IAF, SAF).Main sources of improved efficiency: * Automatic evaluation of complex engine checks.* The “computer-game” effect on the operators.- Upgrade from level 3 to level 4 will result in 5-10% save in run time and fuel consumption Main source of improved efficiency: * Prompt and precise execution of test tasks. 721004011

  25. Considering automation levelsEconomic feasibility analysis of level 3->4 upgrade Consider a possible upgrade of an existing test cell, currently running an F100 engine, using the MCTC at level 3 , to level 4.Estimated (roughly) cost of upgrade: Electronic throttle – 120K$. Software upgrade – 40K$. Mechanical + PLC upgrade – 40K$. Total Cost – 200K$. Assuming: - savings of 10% in fuel consumption.- 9,000 liters per average engine run.- 24 runs per year.- 1$ per 1 liter fuel (??).Investment will cover itself in: 10 years. 721004011

  26. Considering automation levelsConclusions * Level 2 automation is a MUST for any non-trivial test cell This is simply “good engineering practice” and facilitates quality assurance application for the testing process.* Level 3 automation is highly recommended for any test cell with non-trivial testing procedure and a more than minimal work load. This will result in significant time and fuel savings, as well as significant improvement in the reliability and accuracy of the testing.* Level 4 should only be considered if the work load is very high or if other factors (test complexity, required accuracy, “cost of error”) cannot be satisfied by a manually operated test cell. 721004011

  27. Considering automation levelsFinal tip To really optimize the testing procedure:- Check with the engine vendor to find out how the required testing is done at their facility! You may find that their actual procedure is different (and more efficient) than the formal procedure.Case at hand: T56 test cell for TUAF.Thank you for your attention. Any Questions? 721004011

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