The engine injector of the SMILE project, through metal 3D printing design, achieved excellent mixed combustion efficiency, achieved lightweight characteristics, and the number of parts was significantly reduced after integration. 30 scattered parts were integrated into one integrated part.
Challenge:
Design and manufacture of reusable liquid rocket engine ejectors for small satellite launch vehicles
Solution:
Based on its extensive design experience in additive manufacturing, 3DSystems' Leuven Customer Innovation Center uses the metal 3D printer ProX DMP 320 and a nickel-chromium-based superheat-resistant alloy LaserForm® Ni718 (A) for high-temperature applications to meet German Aerospace Center requirements.
Outcome:
• Optimize part characteristics to improve performance
• Integrate jet head components from 30 discrete components into 1 component
• Reduced head weight by 10%
There is a project in the EU Horizon 2020 project called "European SMall Innovative Launcher" (also known as SMILE project), which aims to design a small satellite launch vehicle to send small satellites (up to 150 kg) into orbit synchronized with the sun . The German Space Center Structure and Design Institute in Stuttgart, Germany, is one of 14 participating organizations and is responsible for developing the SMILE project. The institute's focus on liquid propulsion systems is based on the potential for system refurbishment and reuse, thereby providing a more cost-effective solution for small satellite launchers.
In view of the high complexity of the nozzle components of liquid oxygen / kerosene engines, the German Space Center DLR, in collaboration with 3D Systems Customer Innovation Center CIC, designed a 3D printed injector to achieve new performance. 3D Systems' Leuven Center is one of four centers worldwide dedicated to accelerating advanced applications, providing customers with the resources they need to develop, validate, and commercialize products.
The German Space Center decided to use 3D printed heads. They took advantage of the key advantages of additive manufacturing, including the use of a monolithic design to reduce the number of parts and the use of integrated key functions such as cooling runners to better the overall propulsion system performance .
Integrate 30 scattered parts into one integrated part through a metal 3D printed head, and reduce weight by 10%
Marcus Kuhn and Ilya Mueller manage the jet head project at the German Aerospace Center. They said that because 3D Systems' metal printing has been successfully used in the aerospace field, they chose 3D Systems as a partner. Kuhn mentioned: "Based on the aerospace success of DMP metal printing technology, we believe that 3D Systems is well-suited to provide the design to manufacturing of jet heads, which can tap new possibilities for sensor integration, fuel and coolant distribution."
The rocket engine's injector is the part where fuel and oxidant enter the combustion chamber. Successful liquid rocket fuel injectors push components in a specific way, ensuring their atomization and proper mixing to produce the combustion required for a mobile rocket.
Cohen Whit, a project engineer at 3D Systems, said that the liquid fuel injection head envisioned by the German Space Center includes several properties that require DMP printing technology to: "Optimize performance and cooling functions, complex design of pressure and temperature sensor channels and Simplifying assembly and maintaining production consistency and repeatability all require ProX® DMP 320. "
Hot fire test on 3D printed jets, showing good mixing and combustion efficiency
DMP metal printing can help the German Space Center achieve the following goals:
• Optimize part performance with new possibilities for fuel and coolant distribution
• Easy implementation of 3D path pressure and temperature sensor channels
• Eliminate intermediate production and assembly links
• Independent of traditional manufacturing methods, independently optimize thermal, quality and hydraulic performance
• Avoid assembly failure points and improve the quality of the overall design
• Reduce processing steps and produce highly integrated multifunctional injectors
By using metal 3D printing, the aerospace center is able to revolutionize the design of coaxial injectors without the need for multiple components, significantly reducing production time and costs. Reducing the number of parts from 30 to 1 helps to reduce the final weight by 10%, and eliminates the known failure points at the fastening points, which is conducive to reducing related quality control measures and improving system performance.
Print integrated parts with precision metal
3D Systems application engineers use 3DXpert software to prepare the printhead's files for printing. 3DXpert is a comprehensive software that covers the entire metal additive manufacturing process. 3D Systems makes preparations before printing, which makes it easy to process many powders in one place, and also performs printability checks to ensure that no problems occur during the printing process.
The final component of the German Space Center rocket ejector was printed by 3D Systems' metal printer ProX DMP 320 using LaserForm® Ni718 (A), an oxidation- and corrosion-resistant Inconel alloy. This material has good tensile strength, fatigue resistance, creep resistance and long-lasting strength, even when the temperature reaches 700˚c, it is ideal for high temperature applications.
A view inside the injector head shows the complexity enabled by metal 3D printing
After printing, 3D Systems' team heat-treated the part to relieve stress, and used electrical discharge machining (EDM) to remove the part from the forming platform.
Moldless production accelerates design cycle
With DMP technology, the space center can quickly integrate and explore design changes without having to spend time making molds. This capability is critical to the German Space Center's design cycle, as it faces only a few weeks of preparation time when designing and testing a jet head prototype in the first phase.
Kuhn and Mueller said: "Prox DMP 320 and 3D Systems' extensive design knowledge allows us to test more design options in less time."
Metal 3D printing helps the aerospace center optimize coaxial nozzle oxidant and fuel mixing with dual-swirl injector components. Two different cooling schemes were used, each using a narrow channel with a minimum feature size of 0.2 mm and a maximum length / diameter ratio of 45. The design also integrates the filming characteristics of the injector head, enabling engineers to directly adjust the film mass flow at the injector.
Better performance at a more economical cost
Jet head flow: blue = liquefied oxygen; orange = kerosene; red = thin film layer; green = transpiration cooling
By directly integrating the coolant distribution system with the ejector, the space center has improved performance, and engineers can implement and independently control wall sweating and film cooling technology. When used in an injector, a coolant film is formed on the hot side of the combustion chamber to protect the wall structure from high heat flux. This system is considered easier to manufacture and economical than traditional regenerative cooling.
Combined with complex ceramic materials such as ceramic fiber-based composites (CMCS), the design and manufacturing methods developed by the Space Center and 3D Systems have the potential to support multiple reuse of structures and systems developed for jet heads and transfer technology to In other applications.
Liquefied oxygen / kerosene rocket ejector unit with 3D printed jet head and ceramic combustion chamber
To evaluate the new design, the German Space Center performed numerical simulations of the internal flow to estimate the fuel distribution of each propellant and the associated pressure loss in the feed line. Subsequent cold-flow tests showed a good correlation between the numerical and experimental measurements. Thermal testing of the final 3D printed jet head in PLD Space (partner of the SMILE project) in Spain showed that it has good mixing and combustion efficiency when combined with the rocket thrust chamber assembly designed by the aviation center.
Looking forward, the new design and manufacturing processes supported by metal printing will continue to support more complex geometries, reduce time to market by reducing production steps, optimize the use of materials and parts, continuously improve performance, and improve structural integrity to extend the head's Service life.
"We think it's safe to say that 3D printed jet heads have better integration capabilities and lower production time and costs than traditional equivalent parts made with traditional methods," Mueller said.
Additive Manufacturing for Aerospace
Metal 3D printing has become a key technology in the aerospace and aerospace fields, as its advantages are consistent with key needs in the industry, including weight reduction, fuel savings, improved operational efficiency, component integration, accelerated time to market and reduced zero Storage requirements for parts.
Recent projects have proven the effectiveness of 3D Systems' DMP metal 3D printing technology in the aerospace industry:
• The first 3D printed radio frequency (RF) filter has been tested and validated for use in commercial communications satellites. Airbus Defense & Aerospace's new filter reduces weight by 50% over previous design
• Thales Alenia Aerospace cooperated with 3D Systems to reduce the weight of the titanium bracket by 25%, which has a better stiffness-to-weight ratio than traditional methods.
• Engine parts manufactured in a project of the European Space Agency (ESA), which reduced weight, simplified assembly, accelerated manufacturing, and made it easier to adapt post-design
• A topology-optimized aircraft support that reduces weight by 70% and meets all GE Aviation functional requirements