Measurement equipment:

  • Fan: Sanyo Denki 9BMB24P2H01
  • Pressure sensor: Sensirion SDP816-500PA
  • Arduino uno

Datasheets are available in the datasheets folder.

Relevant equations for setup:

Ventury flow: Q=\frac{π}{4}d^2 \sqrt{ \frac{2 \Delta p}{\rho_l} }
Reynolds number: Re = \frac{\rho_l l v }{\mu}
Darcy-Weisbach: \Delta p = \frac{128}{\pi} \frac{\mu Q}{d^4} L
Blasius: \Delta p = 0.158 L \rho_l v^{1/4} d^{-5/4} v^{7/4}

https://en.wikipedia.org/wiki/Darcy%E2%80%93Weisbach_equation
https://www.sciencedirect.com/topics/engineering/blasius-equation
https://en.wikipedia.org/wiki/Venturi_effect

Validation target(s):

  • Flow through the system
  • Pressure drop over the test specimen
  • Calibration of the pressure sensor

Validation strategy

  1. Pressure sensor: Calibration measurement for the Sensirion SDP816-500PA pressure sensor, calibrated using a water column setup.
  2. Blocked flow: Blocking the exit port of the system
  3. Open flow: Running the system without any specimen located at the inlet or exit
  4. Known resistance: A known flow resistance placed at the inlet or exit
Real value [Pa]Measured value [Pa]
00
4939
9884
196178
294278
392370
490466
Pressure sensor calibration

Conclusion

  1. The sensor calibration graph shows an offset up to 20 Pa.
  2. The blocked flow shows a maximum pressure of 490 Pa. This maximum pressure is in accordance with the zero-flow pressure of the Sanyo Denki 9BMB24P2H01 air fan.
    The measured flow can be devoted to internal leakages and small counter flows in the fan. 
  3. The flow through the system is calculated using the venture principle. The pressure difference between the wide and narrow part of a tube gives the flow speed. The flow up to 200 L/min shows a very small static pressure, maximum 8 Pa static pressure can be devoted to the under pressure due to flow velocity in the exit of the system.
  4. The known resistance was a 2 meter long aluminium tube with a 12 mm cross-section diameter. The pressure drop over the tube is calculated with the Darcy-Weisbach equation for a Reynolds number up to 2000. Above 2000 the flow becomes turbulent and the Blasius equation predicts the pressure drop most accurate. The difference between the measured and calculated resistance is negligible.