ME 322: Instrumentation Lecture 41

1. ME 322: InstrumentationLecture 41 May 2, 2014 Professor Miles Greiner

2. Announcements/Reminders • Supervised Open-Lab Periods • Saturday 11 AM-2PM, Sunday 11AM-5 PM (drop Friday) • Extra Credit Lab 12.1 • Due in class Monday, 5/5/2014 • See Lab 12 instructions • Check out Lab-in-a-Box for DeLaMareLibrary and study effect of DT, DTi, TSP, heater and TC locations • Only 0.5% of grade, but good practice for Labs 9 and 12 • Lab Practicum Finals (May 6-14) • Guidelines, New Schedule • http://wolfweb.unr.edu/homepage/greiner/teaching/MECH322Instrumentation/Tests/Index.htm • How many of you will graduate this year (2014) or next (2015). • If it will be later than 2015, was there something the ME Department did that delayed your graduation?

3. Possible Elective Course • MSE 465/665: Fundamentals of Nuclear Power • Professor N. Tsoulfanidis nucpower@sbcglobal.net • TuTh5:30-6:45 PM, LME 316 • Pre/Co-requisites: • Interest in Nuclear Energy; • MATH 181; • MSE 232 (can be waived) • Textbook: • Measurement & Detection of Radiation, N. Tsoulfanidis and S. Landsberger, 3rd Ed, CRC Press (2010); ISBN-10: 1420091859

4. Lab 10: Equivalent Endpoint Mass LE LB Clamp MW • Beam is not massless, • Its mass affects its motion and natural frequency • (linear sum) • mass of weight, accelerometer, pin, nut • (contribution form beam mass) LT MT ME Beam Mass MB

5. Lab 11 Unsteady Speed in a Karman Vortex Street • Nomenclature • U = air speed (instead of V) • VCTA = Constant temperature anemometer voltage • Two steps • Statically-calibrate hot film CTA using a Pitot probe • Find frequency, fP with largest URMS downstream from a cylinder of diameter D for a range of air speeds U • Compare to expectations (StD= DfP/U = 0.2-0.21)

6. Setup myDAQ Variable Speed Blower Hot Film Probe VCTA Barometer PATM TATM Plexiglas Tube CTA • Measure PATM, TATM, and cylinder D • Find air mfrom text • A.J. Wheeler and A. R. Ganji, Introduction to Engineering Experimentation, 2nd Edition, Pearson Prentice Hall, 2004, p. 430 • Tunnel Air Density DTube Cylinder Pitot-Static Probe Static Total PP - + 3 in WC IP

7. Calibration Calculations • Based on analysis we expect

8. Hot Film System Calibration • The fit equation VCTA2 = aU0.5+b appears to be appropriate for these data.

9. How to Construct VI (Block Diagram) • Use for both static-calibration and unsteady measurements • Don’t need to store speed vs time

10. Front Panel

11. Unsteady Speed Downstream of a Cylinder • When the cylinder is removed the speed is relatively constant • When the cylinder is installed, downstream of it • The average speed is lower compared to no cylinder • There are oscillations with a broadband of frequencies

12. Fig. 4 Spectral Content in Wake for Highest and Lowest Wind Speed (a) Lowest Speed URMS [m/s] fp = 751 Hz (b) Highest Speed URMS [m/s] fp = 2600 Hz • The sampling frequency and period are fS = 48,000 Hz and TT = 1 sec. • The minimum and maximum detectable finite frequencies are 1 and 24,000 Hz (not all are shown). • It is not straightforward to distinguish fP from this data. Its uncertainty is wfp ~ 50 Hz.

13. Dimensionless Frequency and Uncertainty • UA from LabVIEW VI • fP from LabVIEW VI plot • ½(1/tT) or eyeball uncertainty • Re = UADr/m (power product) • StD = DfP/UA(power product)

14. Fig. 5 Strouhal versus Reynolds • The reference value is from A.J. Wheeler and A.R. Ganji, Introduction to Engineering Experimentation, 2nd Edition, Pearson Prentice Hall, 2004, p. 337. • Four of the six Strouhal numbers are within the expected range.

15. Process Sample Data • http://wolfweb.unr.edu/homepage/greiner/teaching/MECH322Instrumentation/Labs/Lab%2011%20Karmon%20Vortex/Lab%20Index.htm

16. Lab 12 Setup • Measure beaker water temperature using a thermocouple/conditioner/myDAQ/VI • Use myDAQ analog output (AO) connected to a digital relay to turn heater on/off, and control the water temperature • Use Fraction-of-Time-On (FTO) to control heater power

17. VI Block Diagram • Modify proportional VI • http://wolfweb.unr.edu/homepage/greiner/teaching/MECH322Instrumentation/Labs/Lab%2012%20Thermal%20Control/Lab%20Index.htm

18. Figure 1 VI Front Panel • Plots help the user monitor the measure and set-point temperatures T and TSP, temperature error T–TSP, and control parameters

19. VI Components • Input tCycle, fSampling, TSP, DT, and DTi • Measure and display temperature T • Plot T, T-TSP(error), TSP, TSP-DT, and log(DTi) • Increase chart history length, auto-scale-x-axis • Write to Excel file (next available file name, one time column) • Calculate • and • (shift register), • Limit FTO+FTOi to >0 and <1 • Display using slide indicators • Write data to D/A output within a stacked-sequence loop (millisecond wait)

20. Figure 3 Measured, Set-Point, Lower-Control Temperatures and DTi versus Time • Data was acquired for 40 minutes with a set-point temperature of 85°C. • The time-dependent thermocouple temperature is shown with different values of the control parameters DT and DTi. • Proportional control is off when DT = 0 • Integral control is effectively off when DTi = 107[10log(DTI) = 70]

21. Figure 4 Temperature Error, DT and DTi versus Time • The temperature oscillates for DT = 0, 5, and 15°C, but was nearly steady for DT = 20°C. • DTi was set to 100 from roughly t = 25 to 30 minutes, but the system was overly responsive, so it was increased to 1000. • The controlled-system behavior depends on the relative locations of the heater, thermocouple, and side of the beaker, and the amount of water in the beaker. These parameters were not controlled during the experiment.

22. Table 1 Controller Performance Parameters • This table summarize the time periods when the system exhibits steady state behaviors for each DT and DTi. • During each steady state period • TA is the average temperature • TA – TSP is an indication of the average controller error. • The Root-Mean-Squared temperature TRMS is an indication of controller unsteadiness

23. Figure 5 Controller Unsteadiness versus Proportionality Increment and Set-Point Temperature • TRMS is and indication of thermocouple temperature unsteadiness • Unsteadiness decreases as DT increases, and is not strongly affected by DTi.

24. Figure 6 Average Temperature Error versus Set-Point Temperature and Proportionality Increment • The average temperature error • Is positive for DT = 0, but decreases and becomes negative as DT increases. • Is significantly improved by Integral control.

25. Process Sample Data • http://wolfweb.unr.edu/homepage/greiner/teaching/MECH322Instrumentation/Labs/Lab%2012%20Thermal%20Control/Lab%20Index.htm • Add time scale in minutes • Calculate difference, general format, times 24*60 • Figure 3 • Plot T, TSP, DT and 10log(DTi) versus time • Figure 4 • Plot T-TSP, -DT, 10log(DTi) and 0 versus time • Table 1 • Determine time periods when behavior reaches “steady state,” and find and during those times • Figure 5 • Plot versus DT and DTi • Figure 6 • Plot versus DT and DTi