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Had too much time probably, and I wanted to experiment with phenomenon where higher velocity narrow air stream sucks more ambient air into the stream. Like in e.g. nemo Vortex inflation bags. 3D printed few nozzles:
and experimented with inflating a raft (MRS Microraft) with lungs & inflation bag. High velocity stream comes from the small nozzle (from bottom to top in the first photo), catches some ambient air and enters the second nozzle that fits packraft valve.Results:
Does not work with inflation bag, at least not with 3-7mm nozzle sizes. Pressure from the bag is low and more suitable for the full valve opening.
With mouth it was much better. Inflation of the raft in 1½ – 2 minutes which is just slightly more than with a bag. And the best is the nozzle (3mm diameter was good for me) gives some resistance to blowing so head does not get dizzy from huffing and puffing. Nozzle really seems to multiply the ingoing air as I only needed about ten breaths and my lung volume certainly ain’t 30 liters.Useful or not? Hmmm… Inflation by mouth still is a small sports exercise. On the other hand the inflation device is small and compact compared to inflation bag (which ain’t that big either):
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“I wonder if aiming a drinking straw at the valve opening and blowing through it would also work.”
It does. I started with various everyday objects. Ballpoint pen barrel was quite ok. The structure above just helps to aim in the middle.
Forgot about the 3D-model: you need to drill the nozzle open to 3-4mm (1/8 – 1/6″). Print has a rough surface that weakens airflow.
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STL-files of the nozzles if someone is interested in printing:
https://drive.google.com/file/d/1JENGRPHTo1_nk3GdEx0I47fs0Hq4R9VT/view?usp=drive_linkThe rods connecting the two nozzle parts are cut from the most common 2mm (14 gauge) bicycle spoke. And superglued into the holes of the 3D model
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