Because electrospray engines are more effective in using propellants than conventional chemical rockets, they are more suitable for precise orbit maneuvers. However, the electrospray transmitter produces less thrust, so it generally uses a set of transmitters in parallel and comparable specifications.
The difficulty is that these multi-channel electrospray propellants were previously mainly made thanks to costly and long semiconductor rooms, and high production environment requirements have limited their large-scale manufacture and the range of applications of these devices.
To meet these challenges, MIT engineers have developed an electrospray engine printed in full 3D. It can reach rapid production thanks to commercially available 3D print materials and technologies, with a manufacturing cost of a small part of traditional propellants, and because 3D printing technology is compatible with space manufacturing technology, this type of device can even be made in space.
Meanwhile, researchers successfully overcome the challenges encountered during the manufacture of complex devices, including macro and micro-components, developing a modular process that integrates two 3D printing methods, ensuring that all components work perfectly.
The prototype propellant they have developed consists of 32 electrospray issuers which operate together to produce a stable and uniform propellant flow. Most importantly, the push it generates is no less than that of the jet electrospray engines of traditional droplets.
With this technology, astronauts could soon be able to print and quickly create a satellite engine in space without having to wait for it to be sent from the earth.
Currently, research results have been published inAdvanced scienceon advanced science). The corresponding author of this article is Luis Fernando Velásquez-García, principal researcher at the MIT Microsystems Technology Laboratory; The first author is Hyeonseok Kim, a student graduated in MIT mechanical engineering.
“The traditional semiconductor manufacturing technology seems to be incompatible with the concept of input entry into space in space, and we hope to simplify and popularize the manufacture of space material equipment. In this work, we offer a new way to use manufacturing technologies more widely available to produce high performance equipment, so that more people can easily and use it,” said Velásquez-García.
Modular design method
The electrospray engine has an integrated propellant tank and the propellant takes place towards a series of transmitters via the microfluidic channel. The application of an electrostatic field at each emitter tip triggers the electrohydrodynamic effect, making the free surface of the liquid form a conical meniscus, ejecting a flow of droplets loaded at high speed of its apex, thus generating the thrust.
The cleaner the point of the transmitter, it is no longer conducive to carry out the injection of electric fluid of the low -voltage propeller. Consequently, the device also requires a complex hydraulic system to store and regulate the flow of liquid, effectively offering the propellant via the microfluidic channel.
Overall, the network of transmitters consists of 8 transmitter modules, each containing units composed of 4 independent transmitters that work together to form a larger interconnection module system.
“This does not work with a single manufacturing method because the components vary in size, and our main idea is to combine the additive manufacturing method to reach the desired effect, then find a way to connect all the components so that they can work together as effectively as possible,” said Velásquez-García.
To this end, the researchers used two different types of reduction in photopolymerization printing techniques (VPP) which heal light on the photosensitive resin to form a 3D structure with smooth and high resolution characteristics.
The researchers also made the transmitter module using a VPP method called two photon printing. This method uses a very concentrated laser beam to cure the resin in an area defined with precision and build a layer of 3D structure per layer. With its high precision, the researchers were able to create transmitters with very advanced tips at the top, as well as narrow and uniform capillaries to deliver property.
The transmitter module is installed in a square case, which acts to secure each module and provide a propellant to the transmitter, while integrating the transmitter module with the extraction electrode, which triggers the propellant to eject from the top of the transmitter when the appropriate tension is applied. However, due to the low speed and the limited volume of printing technology with two photons, it is also difficult to make larger shells.
The researchers therefore turned their attention to the technology of processing digital light, using projectors the size of a chip to light up the resin, healing the 3D structure layer per layer. “Each technology is very effective on a specific scale. Combining them and co-producing a device allows us to learn from the strengths and weaknesses of the other, and thus to obtain the best results of each approach,” said Velásquez García.
Promote performance improvement
It should be noted that the manufacture of components of the 3D printed electrospray engine is only half of the success. Then, the researchers also conducted chemical experiences to ensure that the printing equipment is compatible with the conductive liquid propellants, which could otherwise corrode the engine and even cause a break. This is crucial for material devices that require long -term operation and require almost no maintenance.
At the same time, they also developed a method to correct each component in order to avoid disalculation affecting performance, while ensuring that the equipment has a good seal.
Finally, they successfully produced prototypes of 3D printing equipment. Thanks to experiences, it has been found that it could generate a push more effectively than larger and more expensive chemical rockets and has performed better than traditional electrospray engines.
In this new study, they explore how to adjust the pressure of the propellant and the adjustment of the voltage applied to the engine affect the droplets. Surprisingly, by adjusting the tension, they reach a wider range of adjustable push beach.
This means that no complex pipelines, valves or pressure signal networks is necessary to regulate the liquid flow, and a lighter, more economical and more efficient electrospray engine can be created. “We have proven that simpler propellers can also get better results,” said Velásquez García.
As for the next research direction, they hope to continue to explore the role of tension regulation, and they also plan to make a denser and a larger range of transmitter modules.
They also declared that the use of several electrodes could be explored later, combining the electro-hydrodynamic injection process which triggers the propellant with the adjustment of the form and speed of the emitted jet. In the long term, they expect to create a new cubeat which uses this electrospray engine entirely printed in 3D during operation and rail off.
This study was funded in part by the Mathworks Fellowship and Newsat project, and part of the study was carried out in the installation of MIT.NANO.
