[Leo Fernekes] has fallen down the Stirling engine rabbit hole. We mustn’t judge — things like this happen in the best of families, after all. And when they do happen to someone like [Leo], things can get interesting mighty quickly.
His current video, linked below, actually has precious little to do with his newfound Stirling engine habit per se. But when you build a Stirling engine, and you’re of a quantitative bent, having some way to measure its power output would be handy. That’s a job for a dynamometer, which [Leo] sets out to build in grand fashion. Dynos need to measure the torque and rotational speed of an engine while varying the load on it, and this one does it with style.
[Leo]’s torque transducer is completely DIY, consisting of hand-wound coils on the ends of a long lever arm that’s attached to the output shaft of the engine under test by a magnetic coupling. The coils are free to move within a strong magnetic field, with a PID loop controlling the current in the coils. Feedback on the arm’s position is provided by an optical sensor, also DIY, making the current necessary to keep the arm stationary proportional to the input torque. The video goes into great detail and has a lot of design and build tips.
We just love the whole vibe of this build. There may have been simpler or quicker ways to go about it, but [Leo] got this done with what he had on hand for a fraction of what buying in off-the-shelf parts would have cost. And the whole thing was a great learning experience, both for him and for us. It sort of reminds us of a dyno that [Jeremy Fielding] built a while back, albeit on a much different scale.
Continue reading “This Custom Dynamometer Is A Stirling Example Of Homebrewing”
Next time you’re making yourself a tunafish sandwich, try to figure out how to build a Stirling engine from the leftovers (translated). If you can pull it off as well as [Killerlot] did we’d say you’ve earned your hacker badge.
The can used in this project was actually sardines in tomato sauce, but the former contents are moot. The can serves as a steam chamber for the sterling engine. A cam rod, piston, and valve are all fashioned from paperclips, along with the support structure that holds them in place. Inside the can is a
damp sponge. When an alcohol lamp is placed beneath the can it heats the water air inside, which creates pressure on the piston, pushing it up until the cam opens the valve, relieving pressure just in time for the cycle to start over again. Momentum is a necessary part of the mechanism and that’s where the CD fly-wheel comes in. See it chugging along in the clip after the break.
Update: Corrected spelling thanks to [Chris Muncy] and removed references to water/steam thanks to this comment from [Khordas].
Continue reading “Tuna Can And Some Other Trash Turned Into A Stirling Engine”
[Mirslav] built this fuidyne engine himself. This is a single piston model but you won’t find any precision milled cylinders here. That’s because fluidyne engines use columns of water as the pistons. In the rig shown above you can see one metal pipe which serves as the cold side of the loop. There’s another hot pipe underneath the insulation that completes the circuit. When that pipe is heated it causes the air inside the loop to expand, forcing the liquid on the open side of the plastic tubing (to the left) to rise. Once that air escapes to the other side of the circuit the water piston in the open tube falls back again. This results in continuous oscillation that can be used to drive a pump using a pair of check valves.
We’ve embedded a couple of videos after the break. You’ll see the system tested by heating one pipe with a hot air gun. But the example seen above uses an induction coil to bring the heat.
Continue reading “Simple Fluidyne Engine”