The Vortex Ring Cannon project is the result of an ongoing investigation into the aesthetic potential of vortex formations. After having completed a project based on the whirlwinds vortex phenomena I was curious to get to know more about vortexes of the ring formation kind. After countless idurations I finally found a reliable way of producing large long lasting vortex ring.

The project was exhibited at Copenhagen Maker Festival 2018



Investigations

Now, I set out to make a machine that should be able to form vortex rings but I also wanted it to beam and control RGB lights onto the rings as they exist the machine as well as be able to control the diameter of the rings themselves. To achieve a varying hole size I thought that it'd be smart to find a mechanism that could prevent mist, used to visualize the rings, from escapeing the firing chamber as well as offer a relatively exact control of the hole diameter. Thus, my investigation into iris mechanisms had begun!

Iris mechanism

First a did a bit of online researching and found a few iris mecanismes that I thought would be interesting to try out. I will not link to them because they are easily found on sites like Thingiverse or GrabCAD. Anyway, below you can see some of the online designs that I cut and tested. They worked great but neither of them allowed for variable hole size. Therefore, I realized that for this I needed something more aperture like.


Again I went to GrabCAD and found a few promising designs, however, none of them was designed for motorization so I had to make a few modifications myself. I imported the Solidworks STL files into Fusion 360 and projected them into a plane. I now had a 2D and laser cutting friendly version of the mechanism. I then added gears teeth to the circumference of the upper most part of the mechanism as well as added a stepper motor mount and a transmission gear wheel to the laser cutting plan.



After making the modifications I went to the local makerspace and had the files laser cut. They only had transparent 3mm acrylic sheet which worked fine for prototyping but was too flexible for continuous use. It worked perfectly in horizontal position but some unexpected friction occurred when the mechanism was positioned vertically. Not having access to a harder material plus the mechanism’s unexpected behavior when held vertically made me skip further investigation, however, it is very likely that I'll be using a aperture/iris mechanism in future projects.



Rainbow projection

During my investigation I realized that it would be extraordinarily beautiful to project a rainbow into the smoke rings. I digged into my boxes containing old electronics and found an low resolution high power projector. I mounted the projector in the bottom of the firing chamber of the experimental setup and installed a round mirror at a 45 degree angle in the middle of the chamber. I then went online to find a image of a color wheel to, via the mirror, be projected onto the vortex smoke rings. This way I hoped to create rainbow colored smoke rings.

Rainbow projection light diagram
Shortest Path

This method of projecting a color wheel onto the smoke rings, however, turned out to not be viable. Since the firing chamber had to be filled with smoke prior to every firing the light from the projector would be blocked by the smoke. This basically meant that one had to choose between light or smoke and since the rings wouldn't be at all visible without smoke I had to cancel my idea of projecting into the rings and once again I had to reconsider my plans for the project.



creation

Okay, so the very first prototype for the project was basically a bucket with a hole cut in the bottom and a plastic film taped to the top. When I hit the film with my hand a vortex ring would exit the hole. I when tried to attach an subwoofer to the top of the bucket and then experimented with different wave inputs. This produced mediocre results and I quickly realized that this would not scale well.

Now, since is wanted rings to be at least 35 cm in diameter I had to scale the setup quite a bit. I was therefore looking for a kind of actuator that would allow a larger setup but shouldn't be very expensive or very complicated to control. Thus I bought myself a very large bucket and made a few experiments using compressed air and pneumatic cylinders as actuators. This worked perfectly! The rings formed effortlessly, traveled further than any of the once made with previous setups. I now knew that pneumatic cylinders was the way to go and by using this kind of actuator I could potentially make the firing chamber as big as I wanted.


At this point I had made several prototypes using various sizes of brackets. I had had some success and felt that I had a good understanding of what worked and what didn’t, however, it suddenly hit me that I was stupid to not just use the entire upper frame as the firing chamber. I was so locked on the idea of using a large cylindrical form for the chamber that I didn’t even realize that I could achieve larger sized smoke rings and a significantly simpler design by mounting sheets on the sides of the steel frame thus utilizing the entire upper half of the frame as firing chamber.


I now knew what the final design should look like and I could start building the machine. First I had to weld together the steel frame. When the frame was done I cut out 6 square pieces of MDF and mounted them to the frame. Before installing the front and back MDF squares I cut a round hole in each, one for where the rings would escape the mashine and one to make sure that a vacuum wouldn't form behind the membrane as the pneumatic cylinders would push it forward. When I fit the smoke machine, air compressor, power supplies and controlling electronics onto the bottom of the frame.



Now it was time to install the pneumatic cylinders and the membrane, that when fired, would actually make the difference in air pressure that creates the vortex phenomena. I then pulled and soldered wires to all the electronic parts, used a lot of acrylic filler to make sure that air would only escape from the exit hole in the front of the machine. I finally write a bunch of code for the ESP32 controller that would check sensors, activate the actuators in the right order and allowed complete control over WiFi.

Now, what do you know - you have got yourself a large wirelessly controllable vortex smoke ring cannon :)


The application for this project consists of an ESP32 microcontroller functioning as both wireless access point and webserver and system controller. The files (HTML, JS & CSS) for the browser interface is stored as SPIFFS on the ESP32 itself and the two-way variable update between the webserver and the Arduino sketch is done by AJAX websocket functionality. If you are interested in seeing/modifying the browser based GUI or the Arduino sketch feel free to visit this - github repo.