How can i calculate the velocity in a wind tunnel

• MattH150197
In summary, the conversation discusses wind tunnel experiments for a wing design, with the wind tunnel set at 50% power and the incidence angle increased from -2 to 14 at 2 deg increments. The speaker is trying to calculate the velocity for each recording but is having trouble remembering how to do so. They mention taking recordings of the wind tunnel temperature, Betz pressure readings, and atmospheric pressure. The other person questions if a Pitot probe was used, and the speaker clarifies that they used a Betz manometer pressure readings which performs a similar function but is cheaper to install. The conversation ends with the other person reminding the speaker to use continuity to relate the two velocities and thanking them for their help.
MattH150197
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.

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?

berkeman
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
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Two pressures will give you a velocity difference. Use continuity to relate the two velocities assuming you know the contraction ratio.

MattH150197
Ah yeah of course, thank you very much!

berkeman

1. How does air velocity affect objects in a wind tunnel?

The velocity of air in a wind tunnel affects the amount of force applied to objects in the tunnel. Higher velocities create greater force, which can impact the performance and behavior of objects being tested.

2. What factors affect the calculation of velocity in a wind tunnel?

The calculation of velocity in a wind tunnel is affected by several factors, including the size and shape of the tunnel, the air pressure, and the design of the test object. Additionally, the type and placement of sensors used to measure velocity can also impact the accuracy of the calculation.

3. How is velocity calculated in a wind tunnel?

Velocity in a wind tunnel is typically calculated by measuring the pressure at different points within the tunnel and using Bernoulli's principle to determine the velocity. This principle states that as the velocity of a fluid (such as air) increases, the pressure decreases.

4. Can velocity be adjusted in a wind tunnel?

Yes, the velocity in a wind tunnel can be adjusted by changing the speed of the fan or adjusting the shape and size of the tunnel. This allows for different wind speeds to be simulated, which can be useful for testing different objects or scenarios.

5. How is velocity in a wind tunnel compared to real-world conditions?

Velocity in a wind tunnel can be adjusted to match real-world conditions by using scaling laws. These laws take into account the size and velocity of the tunnel and the test object, and can be used to accurately simulate conditions that would be encountered in the real world.

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