My current project for BURPG is to design and manufacture a rocket engine capable of handling 600 lbf, using nitrous oxide as the oxidizer and isopropyl alcohol as the fuel.
This engine will be mounted on a new (though smaller) test stand, called VEGAS. Our current test stand currently has many problems. While it is powerful, it requires the entire team to move out of our lab and it isn't very modular, and due to that we don't take it out to test very often. With VEGAS, we aim to make hands-on testing more accessible for new members and provide new ways for them to learn about rocket systems.
Initially, this rocket engine was going to use ablative cooling to avoid complex cooling types such as regenerative and film. This was chosen to lower the barrier of entry and introduce the basic concepts to new members more simply. However, due to budgeting constraints, we had to move on from an ablative engine. While it would have been cool to learn about ablatives, custom graphite nozzles were too costly. Additionally, premade graphite nozzles with dimensions that were similar were readily available to purchase, however, that would require the other system teams to change their designs. As a result, we chose to create a heat sink engine.
I recently presented a successful conceptual design review. Due to this success, my team allowed me to progress directly to the critical design phase due to the amount of information I showcased. My presentation covered:
- geometry validation through calculations
- CAD modeling and assembly of nozzle and chamber in SolidWorks
- heat transfer analysis
- stress analysis
- bolt calculations
- manufacturing plan
Before this review, I switched froma conical nozzle to a bell nozzle. Originally, I chose a conical shape as it was easier to manufacture in-house, but I opted for a bell nozzle since the geometry of the converging end was complex regardless.
The most difficult part so far has been the heat transfer analysis. Since I have not taken the course in school yet, I relied on reading research papers and meetings with professors to accurately model the problem.
I am working on refining my heat transfer analysis and using Ansys Mechanical to simulate the heat transfer and stress to justify my calculations. Furthermore, I have been spending time at the machine shop to practice using the CNC lathe. While I have used a manual lathe before, I have not have much experience operating a CNC lathe. So, I am using scrap metal from previous BURPG projects and practice by making a subscale version of the nozzle.
After finishing the nozzle and chamber, I plan to design a showerhead injector. Members on my team have already designed a swirl and pintle injector for the engine, so I want to offer a different option when new members want to see the difference between injector designs.