Session: IMECE Undergraduate Research and Design Exposition

Paper Number: 116686

116686 - Preliminary Design of a Small Regenerative Bipropellant Liquid Rocket Engine Using Additive Manufacturing 

The manufacturing complexity of traditional liquid rocket engines has historically been very high and ends up costing significant time and money. This is because some parts of the engine like cooling channels and injectors tend to make for complex geometries that are difficult to both design and manufacture. Even for small rockets the cost and complexities are not historically trivial. In recent years, additive manufacturing has been making progress in terms of reliability and cost of manufacturing. It is to the point that complex parts can be cheaper to manufacture additively than with traditional methods. This is especially true for prototyping because additive manufacturing is much cheaper for manufacturing one-off parts. Also, it can open opportunities for more weight-efficient and functional designs. AM does have some significant drawbacks depending on the method used but these are in general surface roughness, wide tolerances, and allowable overhang angle. 

This paper aims to explore how additive manufacturing can reduce complexity and aid the design of small, low-cost rocket engines. Toward this objective, a regeneratively cooled system with Liquid Oxygen and Kerosene as propellants was chosen. Initial engine specifications were chosen, and nozzle geometry was calculated using publicly available design codes. Cooling channel, nozzle, manifold, and injector designs were drafted with consideration for additive manufacturing. The designs are discussed and compared to similar traditionally manufactured engines to give reference for a comparison of the manufacturing methods. For detailed design, a manufacturer was chosen to give clear design constraints. The manufacturing is outsourced to a low-cost online additive manufacturing service. The service uses the Selective Laser Melting printing method and can print with aluminum, copper, stainless steel, Inconel, and other alloys. Design calculations and thermal, mechanical, and fluid simulations for the aforementioned systems are presented and optimizations are explored. Initially, a one-dimensional approximation is used for calculations regarding the wall heat transfer and fluids. Then the results are used as a starting place for a two-dimensional thermo-mechanical simulation of the wall and cooling channels. This was solved iteratively using analysis software  paired with a script using equilibrium to calculate the combustion chemistry. 

To test the engine, a pressure feed system was integrated. For this, the UC Davis Aggie Propulsion Lab engine Mu test stand was used. This test stand has a regulated, pressure-fed, pressurization system with instrumentation capabilities yielding mass flow rate and tank pressure. The system can also have more sensors added for data such as pre and post cooling channel temperatures and pressures. Under these constraints it was found that the additively manufactured rocket poses significant benefits when compared to traditional methods at this scale.

Presenting Author: Emmett Moore University of California, Davis

Presenting Author Biography: I am a Materials Science and Engineering major at University of California, Davis aspiring to be a liquid rocket propulsion engineer. In 2020-2021 I was the Vice president and project manager of the college organization Liquid Propulsion Group where we designed, manufactured, tested a kero-lox liquid rocket engine. I am currently a mentor and member of the college organization Aggie Propulsion Lab which is also building a kero-lox liquid rocket engine. I was interested in doing this research because I am interested in propulsion and wanted to design a low-cost regenerative rocket engine and I am presenting the current state of the project.

Authors:

Emmett Moore University of California, Davis
Paul Erickson University of California, Davis