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O-805 Valkyrie
Columbia University Rocketry's Hybrid Engine
Columbia University Rocketry builds and tests hybrid engines from scratch for competition at the Spaceport America Cup. As a lead of the Propulsion - Combustion Chamber subteam, I oversee the development of the engine from injector to nozzle exit. Valkyrie is our 2022-2023 engine that flew on our rocket this summer, placing our team third in our category (Student Researched and Designed Hybrids).
Specs
Fuel
Paraffin+microcrystalline wax, 50/50
Oxidizer
Nirtous oxide, liquid
Thrust
805lbf
Chamber pressure
350psi
Burn time
7.4s
Feed system
Pressure-fed (blowdown, autogeneous pressurization)
Cooling
Ablative phenolic chamber, radiative graphite nozzle
Chamber/nozzle
Valkyrie's chamber is made of Aluminum 6061 tube stock, and has a phenolic cartridge-like liner to retain the fuel grain and insulate the chamber OML. The nozzle is entirely graphite, and radiates heat through a thin Aluminum jacket/retainer.
Valkyrie assy
2D nozzle CFD, ANSYS Fluent
Chamber machining mishap
Valkyrie assy
1/11
Injector
Exploded view
Full assy in SW
Frosty injector after cold flow test
Exploded view
1/11
The Valkyrie injector is an unlike impinging doublet injector, with a predominantly axial stream to wet the entire fuel grain port (IML). There are three major components: the hemispherical manifold, the injector body, and the injector coin (internal). I designed the injector with the intention of iterating on the coin (and, thus, ox. mass flow) quickly; you can see that the coin seat can accommodate any coin with a particular profile, which is easily machined on the lathe. After three iterations, the injector provided a mass flow matching our designed ox mass flow to within .01 kg/s.
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