1. ME 322: Instrumentation Lecture 16 February 25, 2015 Professor Miles Greiner Lab 6 calculations (Excel demo)

2. Announcements/Reminders HW 6 due Friday Career Fair, Tomorrow, February 26, 2015 – Internships – Prepare for permanent employment next year – www.unr.edu/engineering/careerfair www.unr.edu/engineering/careerfair – Differential Fees pay for this

3. Lab 6 Air Volume Flow Rate and Centerline Speed in a Wind Tunnel Plexiglas Tube and Schedule-40 Pipe have different diameters Control flow rate using a variable speed blower – Cover blower exit for very low speeds For a range of flow rates, measure – Volume flow Q rate using a Presso Venturi Tube (in pipe) – Centerline speed V C using a Pitot-Static Tube (in Plexiglas tube) For both measure pressures difference using calibrated transmitters/digital multimeters Both V C and Q increase with blower flow rate – Is V S < V C < V P ?

4. Instrument Schematic D Tube D Pipe P PGPG PVPV Static Total + + - - IVIV IPIP IGIG + - Variable Speed Blower Pipe Plexiglas Tube Pitot-Static Probe V C Venturi Tube Q Atm 40 in WC 3 in WC 40 in WC Barometer P ATM T ATM

5. Summary

6. During Experiment

7. Consistency Check For a given volume flow rate Q – V S = Q/A – V P = 2V S What area should we use? – A Pipe or A Tube

8. Measured Results Determine speed and flow rate uncertainty for a range of blower speeds

9. Demonstrate Excel Calculations Lab 6 Sample Data – http://wolfweb.unr.edu/homepage/greiner/teaching/ MECH322Instrumentation/Labs/Lab%2006%20Fl uid%20Flow/Lab%20Index.htm http://wolfweb.unr.edu/homepage/greiner/teaching/ MECH322Instrumentation/Labs/Lab%2006%20Fl uid%20Flow/Lab%20Index.htm Values and uncertainties Pressure Units Error Bars

11. Pressure Transmitter Uncertainty

12. Static Pressure

13. Static Pressure Uncertainty

14. Transmitter Pressures 3” or 40” WC FSWρWρ Pitot3” WC1.9 Pa Venturi and Gage 40” WC25 Pa

15. Gas Pressure and Density