Cold Gas Thruster
I worked with a teammate to design, manufacture, and test a cold gas thruster while adhering to specific parameters. The project utilized fundamental concepts of compressible flow and nozzle design theory from "Rocket Propulsion Elements."
Project Goals & Background
This served as an intro project into the BU Rocket Club team to help familiarze members into the team work flows and learn basic CAD modeling in Solidworks. The project had the following goals:
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Understand the principles and equations behind converging-diverging bell nozzles
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Design and model a basic cold gas thruster based on provided project parameters
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Perform FEA simulations to verify wall thickness and structural integrity
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3D print the final design in ABS and test
Provided Values
Inlet Pressure (P1)
90 psi
Exit Pressure (P2)
2.1 psi
Atmospheric Pressure (P3)
14.7 psi
Throat Pressure (Pt)
47.5 psi
Inlet Air Temperature (T1)
67.7 F
Inlet Diameter (D1)
16.5 mm
Minimum Throat Diameter
7.75 mm
Design & Validation Overview
Section View
The geometry of the nozzle is optimized based on the natural expansion of compressed airflow. We designed "converging, diverging bell nozzle," also known as a de Laval nozzle with an 80% bell contour length.
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FEA & CAD
We created then created a CAD model in SolidWorks, which we performed FEA on to ensure it would be safe to test with an input pressure of 90 psi. Material properties are based on ABS plastic
Testing
After verifying everything, the nozzle was 3D printed out of ABS plastic. We then put it onto the club provided load cell and fired it up! Results can be found below
What is a Cold Gas Thruster?
It's a simple propulsion system that uses the expansion of a pressurized gas to generate thrust.
The simple design enables the thrusters to be smaller than conventional rocket engines, making them ideal for missions with strict volume and weight constraints. This simplicity also makes them an excellent choice for an introductory project in the rocket club, where new members like myself can get hands-on experience with independent research, CAD modeling, and iterative design reviews while learning the fundamentals of propulsion and engineering workflows.
Cold Gas thruster used to stabilize SpaceX Falcon 9 during landing
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Results
Max Thrust
42.8 N
Mass Flow Rate
0.069 kg/s
Thruster Mass
53 grams
Specific Impulse
63.46 s
Development Review Slides