Wind tunnel
- Temperature at each measuring point
- Rotation speed n
- Resistance Fw
Pressure difference ∆p dyn can be directly measured using a Prandtl pitot tube.
1. Flow velocity
To determine the flow velocity, the following formula is required:
2. Density of air
In order to calculate the air density, the following formula is required:
The general gas equation 
Ambient pressure can be directly measured using a barometer.
The dimensionless resistance coefficient is calculated using the formula:
3. Viskösität
The Reynolds number can be determined by calculating the viscosity of the air.
B = 1,503 . 10-6, C = 123,6 und T = t + 273,15K
The kinematic viscosity can be calculated by dividing the dynamic viscosity by the density of the air.
4. Reynolds number
The Reynolds number is defined as:
References:
[1] What Are Wind Tunnels? https://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-are-wind-tunnels-k4.html
[2] Windkanal: https://de.wikipedia.org/wiki/Windkanal
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Many thanks 🙏