STAR
STAR
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Space Technologies And Rocketry at Berkeley, is UC Berkeley’s premier competition high-power rocketry team that I joined my freshman year of college. I am currently the project manager for the Alula project, the club's second iteration liquid engine. Most of the work I did here has been focusing on valve design, simulations, and general integration of airframe, electronics and the propulsion system.
Space Technologies And Rocketry at Berkeley, is UC Berkeley’s premier competition high-power rocketry team that I joined my freshman year of college. I am currently the project manager for the Alula project, the club's second iteration liquid engine. Most of the work I did here has been focusing on valve design, simulations, and general integration of airframe, electronics and the propulsion system.
PRESSURE ACTUATED LINEAR VALVE
This is the second valve I designed, aiming to tackle some of the problems I encountered after making and testing the pyro valve I made, shown below. This pressure actuated valve is intended to be made with stainless steel for corrosion resistance from liquid oxygen. The biggest problem with the pyro valve was that it would leak under cryogenic temperatures and high pressure, likely because of the viton O-rings that were not designed for that temperature. For this valve, we switched to PTFE spring loaded seals that were capable of handling these temperatures, but that required a complete valve redesign. This new design makes sure the sealing surfaces do not slide past any ports, and the grooves were tightly toleranced according to EriksUSA Spring Energized seals design guide.
This is the second valve I designed, aiming to tackle some of the problems I encountered after making and testing the pyro valve I made, shown below. This pressure actuated valve is intended to be made with stainless steel for corrosion resistance from liquid oxygen. The biggest problem with the pyro valve was that it would leak under cryogenic temperatures and high pressure, likely because of the viton O-rings that were not designed for that temperature. For this valve, we switched to PTFE spring loaded seals that were capable of handling these temperatures, but that required a complete valve redesign. This new design makes sure the sealing surfaces do not slide past any ports, and the grooves were tightly toleranced according to EriksUSA Spring Energized seals design guide.
PYRO VALVE
The first valve I designed for the liquid engine was this pyro valve that is used to actuate liquid oxygen and ethanol lines. Black powder is stored at a cavity in the top hex cap and when ignited with an e-match, forces the piston downwards and allows liquid to flow through. I chose pyro valves because they were extremely light weight compared to other valve actuators and worked reliably. The actuator is simply 0.05g of black powder instead of a big solenoid or servo, and it doesn't require a large battery supply. I designed the valve in Solidworks and machined the prototype out of aluminum, and the final product that will be flown on our rocket will be made from stainless steel for cryogenic resistance. I ran thermal and pressure drop simulations in Solidworks and compared those results to the tests we did in real life.
The first valve I designed for the liquid engine was this pyro valve that is used to actuate liquid oxygen and ethanol lines. Black powder is stored at a cavity in the top hex cap and when ignited with an e-match, forces the piston downwards and allows liquid to flow through. I chose pyro valves because they were extremely light weight compared to other valve actuators and worked reliably. The actuator is simply 0.05g of black powder instead of a big solenoid or servo, and it doesn't require a large battery supply. I designed the valve in Solidworks and machined the prototype out of aluminum, and the final product that will be flown on our rocket will be made from stainless steel for cryogenic resistance. I ran thermal and pressure drop simulations in Solidworks and compared those results to the tests we did in real life.
One of the largest problems I faced when designing the valve is the thermal contraction that all of the parts encounter under cryogenic temperatures. The coefficient of thermal expansion for the viton o-rings is higher than the steel surrounding it, meaning the o-rings will shrink more when exposed to liquid oxygen and potentially ruin the seal. To solve this, I sized up the internal groove diameter from the parker o-ring guide and made the tolerances much tighter when I machined the parts so that even when the o-rings shrank there was still enough squish to keep a tight seal.
One of the largest problems I faced when designing the valve is the thermal contraction that all of the parts encounter under cryogenic temperatures. The coefficient of thermal expansion for the viton o-rings is higher than the steel surrounding it, meaning the o-rings will shrink more when exposed to liquid oxygen and potentially ruin the seal. To solve this, I sized up the internal groove diameter from the parker o-ring guide and made the tolerances much tighter when I machined the parts so that even when the o-rings shrank there was still enough squish to keep a tight seal.
Here is a demonstration of the stainless steel valve actuating pressurized liquid nitrogen:
THRUST CHAMBER
I used RPA to model the ideal thrust chamber shape for our specific flight vehicle and the goal we wanted to accomplish. We decided against the standard bell shaped nozzle because that shape was too difficult to manufacture with our limited tools. Instead we opted for a deLaval nozzle, which gave us similar performance. I ran thermal and force simulations in Solidworks to make sure it wouldn't melt during launch and in the near future I will be machining the part out of aluminum.
L1 PROJECT
I built and launched a rocket to obtain my L1 certification from the National Association of Rocketry. Before building, I did simulations in OpenRocket to calculate the apogee of the flight path and the optimal time to launch the parachute. The launch was a success, the rocket was recovered, and I am L1 certified! The project gave me a great overview of each part of the rocket process, and even though I want to specialize in the propulsion aspect, learning about how the propulsion element interacts with the airframe or recovery system gave me a great perspective while I designed the larger rockets our team would launch.
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