Bernoulli effect on new vent design

[Baluncore]

Have Fun!

Maybe a shorter form of the vuvuzela. $2.50 each.
https://www.amazon.com/dp/B0834N3JXY/?tag=pfamazon01-20

 

[NatureFriend]

Thank you all.

 

[NatureFriend]

Baluncore, I have one (final) question. You suggested thinning the wall of the upper chimney. Was the purpose to encourage more heat absorption thus increasing the stack effect? If so, could increasing the surface area for heat absorption by adding short, black ridges along this section accomplish the same thing?

 

[Baluncore]

If so, could increasing the surface area for heat absorption by adding short, black ridges along this section accomplish the same thing?

It might, but there are disadvantages. I recommend a thin black metal tube, so the sunlight heated surface is in closer contact with the rising internal air. There will also be an external air current moving up the outside of the stack, that will cool the surface. If ridges were added, they would need to be vertical inside the stack, and horizontal outside. That would increase the internal exchange area, but slow it by increasing the surface area drag, while also providing accommodation for spiders, that will block the airflow.

Unfortunately, the use of PE for construction will supply most of the heat to the nest space, and so drive the stack. The fine detail of the upper stack will be relatively unimportant, too little and too late to have a significant effect. The only way to change that would be to insulate the nest box, and paint it externally, reflective white.
The more I think about it, the more I like paper-mache, laid up by child labour, on a hanging party balloon, partly filled with water to give it the gourd shape with a tapered stem-stack.

 

[NatureFriend]

There are thousands currently being used of the PE design. Reportedly they can last 20 years. I am trying to come up with a vent for these existing and surely thousands more to be sold over time.

I have a good idea now what needs to be done to make the vent more effective. Thank you