How can i calculate the velocity in a wind tunnel

AI Thread Summary
To calculate the velocity in a wind tunnel, use the Betz manometer pressure readings alongside the atmospheric pressure and wind tunnel temperature. The Betz pressure readings can provide a velocity difference similar to a Pitot tube, and knowing the contraction ratio is essential for accurate calculations. The continuity equation can relate the two velocities derived from the pressure readings. It's important to ensure that all measurements are taken consistently at each incidence angle. This approach will help determine the velocity for each recording effectively.
MattH150197
Messages
60
Reaction score
3
Ive done some wind tunnel experiments for a wing design i made, the wind tunnel was set to 50% power and the incidence angle was increased from -2 to 14 at 2 deg increments, how do i calculate the velocity for each recording? I've done this before but I am just having a mental block on remembering how to calculate the velocity as i haven't done any wind tunnel experiments in a couple of years. The recordings i took were: wind tunnel temp at the time of each recording, the Betz pressure reading of the wind tunnel for each recording and the atmospheric pressure of the lab room.
 
Engineering news on Phys.org
I operate wind tunnel for a living and I don't know what a Betz pressure reading is.

Did you not employ a Pitot probe of any kind?
 
  • Like
Likes berkeman
boneh3ad said:
I operate wind tunnel for a living and I don't know what a Betz pressure reading is.

Did you not employ a Pitot probe of any kind?
Sorry should have given the full name, betz manometer pressure readings, I think they it does a similar job as a pitot tube but is just cheaper for installation.
 
This is a diagram showing the location of the pressure readings.
 

Attachments

  • Betz Pressure Tapping.jpg
    Betz Pressure Tapping.jpg
    3.6 KB · Views: 759
Two pressures will give you a velocity difference. Use continuity to relate the two velocities assuming you know the contraction ratio.
 
  • Like
Likes MattH150197
Ah yeah of course, thank you very much!
 
  • Like
Likes berkeman
Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
Back
Top