1. ME 322: Instrumentation Lecture 34
April 13, 2016
Professor Miles Greiner
Lab 11 Calculations, Sample data demo
Ran out of time in 2016

2. Announcements/Reminders
HW 11 Due Friday
Tutorial: Thursday 7 PM, SEM 321 unless Joseph lets you know otherwise
This week: Lab 10 Vibrating Beam
Sign up for 45-minute Lab 11 periods with your partner in lab
For Lab 11, each lab day will have a required demonstration for all students to learn how to perform the details of the experiment.
You must be on time to the demo and your lab time (participation grade)
Help wanted (see me
Spring 2016: ME 322 Lab Assistant

3. Announcements/Reminders
Exam solution posted outside PE 213 (my office)
Will consider regrading until Friday, 4/15/2016
If you have a Laptop, you may want to load LabVIEW and bring it to class to follow along, especially next week for Lab 12 (complicated VI)
Lab-in-a-Box
All the equipment for Lab 10 and 12 is in the DeLaMare library basement.
LabVIEW also in Library
You can use this to
See if your VI’s work, and
Practice for the final

4. Internship Opportunities
Nevada National Security Site (Las Vegas)
Nuclear materials packaging internship
Description:
The Orthopedic Implant Company (OIC)
Internship (SolidWorks +?)
Send resumes to Joseph Bozsik

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 Constant Temperature Anemometer (CTA) using a Pitot probe
Downstream from a cylinder of diameter D, find frequency fP with largest URMS for a range of air speeds U
Compare to expectations: StD = DfP /U =

6. Table 1 Cylinder Diameter and Air Properties
Air Viscosity from A.J. Wheeler and A. R. Ganji, Introduction to Engineering Experimentation, 2nd Edition, Pearson Prentice Hall, 2004, p. 430.

7. Calibration Calculations
Based on physical analysis we expect
𝑉 𝐶𝑇𝐴 2 =𝑎 𝑈 +𝑏
𝑈=𝐶 2 𝑃 𝑃 𝜌 𝐴𝑖𝑟 =𝐶 2 𝜌 𝑊 𝑔𝐹𝑆 𝐼 𝑃 −4𝑚𝐴 16𝑚𝐴 𝜌 𝐴𝑖𝑟
𝜌 𝑊 =998.7 𝑘𝑔 𝑚 3
𝐹𝑆= 3 𝑖𝑛𝑐ℎ 𝑊𝐶 𝑐𝑚 𝑖𝑛𝑐ℎ 1 𝑚 100 𝑐𝑚
𝜌 𝐴𝑖𝑟 = 𝑃 𝐴𝑇𝑀 𝑅 𝐴𝑖𝑟 𝑇 𝐴𝑇𝑀 ; 𝑅 𝐴𝑖𝑟 =0.287 𝑘𝑃𝑎 𝑚 3 𝑘𝑔 𝐾
𝑆 𝑉 𝐶𝑇𝐴 2 , 𝑈 = 𝑎 𝑈 𝑖 +𝑏 − 𝑉 𝐶𝑇𝐴 2 𝑖 𝑛−2
𝑆 𝑈 , 𝑉 𝐶𝑇𝐴 2 = 𝑆 𝑉 𝐶𝑇𝐴 2 , 𝑈 𝑎

8. Hot Film System Calibration
The fit equation VCTA2 = aU0.5+b appears to be appropriate for the calibration.
The standard estimate of the error of 𝑉 𝐶𝑇𝐴 2 for given 𝑈 is 𝑠 𝑉 𝐶𝑇𝐴 2 , 𝑈 =0.26 𝑉 2
The standard estimate of the error of 𝑈 for given 𝑉 𝐶𝑇𝐴 2 is 𝑠 𝑈 ,𝑉 𝐶𝑇𝐴 2 = 𝑚 𝑠

9. Unsteady Karman Vortex Flow
Note: Change from before. Do not place the hot film probe directly behind the cylinder. Offset is better
Need to remove cylinder to find UA
Replace cylinder to find spectral content and fP

10. Fig. 4 Spectral Content in Wake for Highest and Lowest Wind Speed
(a) Lowest Speed
URMS
[m/s]
fp = 751 Hz
URMS
[m/s]
(b) Highest Speed
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.
It is straightforward to distinguish fP from this data. Its uncertainty is Wfp = 0.5 Hz.

11. Dependence on Probe Location
Offset
Aligned
Offset is better than aligned with cylinder

12. Dimensionless Frequency and Uncertainty
UA from LabVIEW VI
𝑤 𝑈 =2 𝑈 𝑠 𝑈 , 𝑉 𝐶𝑇𝐴 (68%)
fP from LabVIEW VI plot
𝑤 𝑓 𝑃 = ½(1/tT) or eyeball uncertainty
Re = UADr/m (power product)
𝑤 𝑅𝑒 𝑅𝑒 2 = 𝑤 𝑈 𝐴 𝑈 𝐴 𝑤 𝐷 𝐷 𝑤 𝜌 𝜌 𝑤 𝜇 𝜇 2
StD = DfP/UA (power product)
𝑤 StD StD 2 = − 𝑤 𝑈 𝐴 𝑈 𝐴 𝑤 𝐷 𝐷 𝑤 𝑓 𝑃 𝑓 𝑃 2

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

14. Process Sample Data

16. Fig. 2 VI Block Diagram
Starting point VI

17. Fig. 1 VI Front Panel