[RobertW]

Dear All,

I have developed a 3D model of airflow through: inlet air zone – porous zone – outlet air zone. Porous media represents a large number of pills. In a real process, the air is pumped among these pills.

The viscous and inertial resistances of the porous zone have been calculated based on the velocity v’s pressure drop developed from a virtual (CFD, Fluent) air tunnel. I tried to arrange pills randomly, as they are in reality. I develop now a lab tunnel in order to confirm the data produced by the virtual tunnel.

I am certain that many of you guys have dealt with lab tunnels. Certainly, some of you built such tunnels. I would like to ask you very kindly for your opinion on the design of my tunnel and a little guidance on the purchase of key components of a tunnel. Perhaps you came across some sensors or blowers that are cheap and good and vice versa dear and not reliable. I send attached the concept of a tunnel designed for the needs of pills test.

1. Please share your thoughts on the proposed two designs of the tunnel tailored for an analysis of airflow through pills.

2. I wonder whether it makes sense to design the contraction section of my tunnel of a conical shape (Design 2 in attached file). I intend to measure each velocity a few times by moving the pitot tip up and down (measure velocity across tunnel cross-section). The same is planned for measure of pressures (probes will check pressure near wall and in the centre of tunnel section).
In case it would be advisable to design contraction section of conical shape, for this specific application, the pitot tube would be alocated near the inlet of test section (Design 2) and the distance between this pitot tube and wall of pills would be approx. 150mm.

3. I wonder whether calculation of the pressure lost coefficient for the test section (middle not conical section) would make sense for this scenario. Pills make the biggest ‘job’ here.

4. I search online stores looking for an optimum anemometer/pitot tube in terms of cost/quality. Expected range of velocities to be measured is 0.1m/s – 15m/s. Velocities at which the pressure drop will be measured are: 0.1, 0.32, 0.46, 1.42, 6, 8.25, 10.5, 12.75, 15. Required sensitivity of an anemometer would be, say, 0.02m/s, as the lowest measured velocities will be 0.1, 0.32, 0.46m/s.
https://www.globaltestsupply.com/pro...8aAsWQEALw_wcB
Unfortunately, a lot of devices like this from the link has minimum measurable air velocity 1m/s.

5. I am also looking for a pressure differential measure device. Expected pressure differences are in range 0-500Pa.
I am looking for a unit that would be an economical option. I find units like this linked below, affordable, but they are not suitable for this application.
https://www.valuetesters.com/uei-em2...ssure-kit.html

6. Fixture of pitot tube to the wall of tunnel. I can find pitot tubes having smooth surface only. For obvious reasons I need to make sure that the connection between pitot tube and tunnel wall is airproof. What is more, I will need to move the pitot tube up-down in the tunnel to obtain several measurements for each given inlet velocity. Any ideas on how to fix a regular pitot tube to the tunnel wall?

7. I wonder whether application of compressed air (from pipework in a company) with a sensitive valve (velocity adjustment) would be a reasonable option (instead of a blower with precise adjustable speed).

Thank you.
Regards

[vinerm]

It appears that the query is not related to CFD, but related to development of actual tunnel for physical experiment.