Youtuber Integza has developed a functional open-source 3D-printed prototype of a detonation-driven pulsejet engine.
While pulsejets, valveless engines in which fuel is injected into a pipe before igniting in a series of pulses, have been around for over a century, they tend to emit a low specific impulse. These lightweight propulsion systems can therefore be made with few or no moving parts, making them easy to maintain, but their low efficiency continues to limit their potential in vehicle pushing applications.
To get around this and develop a valveless engine capable of continuous detonation, Integza turned to 3D printing. Using the technology, the YouTuber built his own pulsejet with a combustion chamber, complete with printed fuel and oxygen inlet valves, and based on this prototype, he has since devised a revised metal version, which delivers up to ten pulses per second.
Integza says the engine is “not the fastest it’s ever built,” but with better valves “it should do better.” The YouTuber goes on to add that if he can find a way to build an engine that uses detonation with a continuous flow “thrust would be insane.” With this in mind, Integza has revealed that he is now working on a rotary detonation engine that could deliver a much higher level of efficiency and thrust.
How do detonation engines work?
Essentially, a pulse detonation engine works by injecting oxygen and propellants into long cylinders that are open at one end and closed at the other. Once these pipes are filled, their contents are ignited, causing the fuel to burn and quickly detonate. The pressure of this shock wave, which can travel at speeds up to Mach-10, pushes the exhaust out of the pipe outlet, creating thrust.
A major advantage of pulsejet engines is that they can pressurize the fuel and oxidizer to a high enough pressure to function without the need for a turbo pump. In contrast, typical rocket engines rely on complex, expensive to develop turbo pumps to push fuel and oxidizer into a chamber at a high enough pressure to prevent it from being blown back out.
However, as Integza discovered, pulsejets can also be very noisy, making them unsuitable for powering manned flights, and less energy efficient than combustion engines. As a result, such propulsion systems are more often used to convert thermal energy or power light radio-controlled aircraft than to provide thrust.
Integza’s 3D printed prototype
As Integza explains in its video, pulsejet engines have “smart geometries” that “create a cycle of self-priming air” that mixes with fuel and re-ignites, but this doesn’t allow for continuous thrust. To generate greater amounts of power, the YouTuber theorized that it would be best to “use detonations on this type of motor,” and he tested this theory with a Prusa SL1S 3D printer.
Using the system and a Siraya Tech resin, Integza initially 3D printed a combustion chamber connected to a long acrylic pipe and air and fuel valves. Once ignited by a high-voltage generator controlled via an Arduino controller, the YouTuber wasn’t sure if this setup caused detonations. In order to spice up its engine, Integza therefore resorted to injecting pure oxygen.
This allowed him to achieve an output of 80 meters per second, enough to punch a hole in a piece of paper and pop a balloon. However, not satisfied with this level of thrust, the YouTuber took it further by crafting another prototype from metal, which he says is capable of creating “clean and consistent blasts” while hitting up to ten pulses per second.
When the engine was put on rails, it also proved capable of propelling a platform forward, which is why he describes his prototype as “a great way to investigate detonation”. That said, Integza also believes his design is “flawed due to the pulsed current,” which is why he is now developing a rotational detonation motor, which allows one or more detonations to travel continuously around an annular channel.
The increased power of these engines makes them better suited for vehicle propulsion than conventional pulse-based alternatives, and the YouTuber has now committed to making his own engine in his next video. In the meantime, Integza has made the 3D model design files for its jet engine prototype available for free download, allowing those brave enough to try a 3D print at home.
Content creators like Integza offer creators everywhere an accessible way to learn more about 3D printing and how to use the technology in innovative and exciting ways. In August 2021, Integza itself developed a 3D-printed engine inspired by a Nazi design, powered by a volatile chemical reaction instead of regular fuel.
More recently, YouTuber Akaki Kuumeri has developed a 3D-printed PS5 controller adapter that allows users to play games with one hand. The content creator is now working on a library of 3D printed parts for game controllers that will provide non-standard hand positions and make video game play more accessible.
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Featured image shows Integza’s 3D printed engine prototype during detonation. Photo via Integrza.
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