Video summary

Measurements I - Wind Tunnel Airfoil/Cylinder Pressure Distribution Model Set-Up

Main summary

Key takeaways

Educational

Main ideas / concepts conveyed

  • Wind tunnel test section setup can be modified by interchanging top/bottom blocks using tabs on the sides/bottom edges.
  • For Lab 8 / Measurements 1, the instructor instructs to leave the test section “as is” (do not modify/interchange parts).
  • Different test models (airfoils/cylinder) are mounted using specific alignment features:
    • Loosen two silver screws, position the airfoil so divots fit around them, press flat against the wall, then rotate until the red “0° angle of attack” line aligns.
    • To switch models, loosen/rotate/remove the current one and install the new model, repeating alignment.
  • A manometer system (10 manometers) measures pressure differences:
    • Manometers are numbered 1 through 10, with 1 on the right to 10 on the left.
    • Each manometer is connected to the test model via hoses; the hoses must not be removed or the lab reading will become zero.
    • Each hose has a tag number that indicates which manometer port it connects to.
    • The manometer “zero” is adjusted via a set screw that raises/lowers the fluid column:
      • The instructor sets the baseline to height = 6 so that higher-than-ambient pressure can still show positive height changes (instead of saturating/appearing as zero).
      • They map offsets below this baseline: 5 = -1, 4 = -2, 3 = -3, 2 = -4, 1 = -5 (and similarly for the “above” side).
  • After mounting the model and configuring the manometer:
    • Hook up tubes from the airfoil ports to manometer 1 through 9.
    • Leave manometer 10 open to ambient to serve as the reference for ambient pressure.
  • Wind tunnel + fog visualization workflow:
    • Start the wind tunnel to verify fog machine operation.
    • Use a black background so white fog is easier to see.
    • Pulse the fog machine in five 10-second pulses and adjust its position downward until flow patterns appear clearly on both top and bottom surfaces.
    • To study angle effects, change angle of attack (by loosening thumb screws) and repeatedly activate fog (about another 5 seconds) to observe:
      • Formation of vortexes
      • Progression toward flow separation
      • Past stall, reduced visible activity
    • After finishing, return to 0° angle of attack.
  • Finally:
    • Record manometer height changes and calculate the pressure distribution across the airfoil based on the readings.
    • This constitutes how to use the wind tunnel for the lab.

Detailed step-by-step methodology / instructions (as presented)

A) Set up the wind tunnel test section

  • You can interchange top and bottom blocks by:
    • Pulling tabs on the bottom toward you to remove the bottom block.
    • Doing the same for the top block (on all four sides).
  • For Lab 8 (Measurements 1):
    • Leave the test section “as is” and do not touch it.

B) Install and align the airfoil (or switch models)

  • Identify features:
    • The model (e.g., airfoil) has divots/dents (around the mounting area).
    • There are two silver screws that must be loosened.
  • Procedure:
    1. Loosen the two silver screws.
    2. Place the airfoil so the divots go around the two screws you loosened.
    3. Push the airfoil flat against the wall.
    4. Rotate until the red line aligns with 0° angle of attack.
    5. Tighten to lock position.
  • To switch to another model (cylinder/other airfoil):
    • Loosen, rotate, pull out, and install the new model.
    • Repeat rotation until the 0° reference line is correct, then tighten.

C) Set up the manometer system

  • Manometers:
    • There are 10 manometers labeled 1–10 (right to left).
  • Critical rule:
    • Do not remove hoses attached to the manometer.
    • If hoses are removed, the lab gives a zero result.
  • Connect hoses correctly:
    • Each hose has a tag number at the end.
    • That number corresponds to the manometer number.
    • Example: Hose tag “1” → connects to manometer “1”.
  • Zeroing the manometer:
    • On the back of the manometer is a set screw controlling the fluid column height.
    • Adjust by:
      • Undo the set screw
      • Move the set screw up/down to change fluid height
      • Set it to 6 as the zero point
    • Rationale:
      • Setting zero at 6 allows detection if pressure is higher than ambient, preventing the water from simply moving into the manometer with no readable height difference.

D) Hook tubes from the model to manometers

  • Ports on the airfoil:
    • Start with tube/port #1 through #9.
    • There are 9 ports, so:
      • Connect 1–9 to manometers 1–9 accordingly.
  • Reference:
    • Leave manometer #10 open to ambient.
  • Attachment detail:
    • When connecting tubes, do not push them more than about a quarter inch so they’re easy to remove later.

E) Operate fog visualization and adjust placement

  • Start sequence:
    • Once tubes are connected, start the wind tunnel.
    • Add a black background (to improve visibility of white fog).
    • Pulse fog machine in five 10-second pulses.
  • Fog adjustment:
    • If fog appears too high:
      • Adjust fog machine downward slightly
      • Try again with additional pulses
    • Stop when you can clearly see flow on both top and bottom.
  • Angle-of-attack visualization:
    • Change angle of attack by loosening thumb screws.
    • Then activate fog for about ~5 seconds.
    • Observe vortex formation and repeat increasing angle to see:
      • More vortices
      • Eventual flow separation
    • If you go beyond stall:
      • You may see little/no clear activity.
  • End angle procedure:
    • Return the airfoil to the 0° (red line) position.
    • Note that manometer heights will change after angle adjustments.
    • Use these changes to compute pressure distribution.

Speakers / sources featured

  • An instructor/lab demonstrator (no name provided in the subtitles).

Original video