THE EFFECT OF SWIRL INJECTION PARAMETERS ON A VORTEX-COOLED THRUSTER FABRICATED USING THERMOPLASTIC AND METAL

This paper reports an experimental investigation of the efficiency and cooling performance of a 10N-vortex cooled Propane/Gox bi-propellent thruster designed and tested with different fabrication materials including a thermoplastic combustion chamber, and metal faceplate and nozzle. The study proposes vortex as a possible solution for cooling thrusters made from partially 3D-printed thermoplastic material. This enables the vortex injection method to be used in a single solid piece thruster to minimize the design complexity. This possibly reduces weight, production time, and cost compared to conventional cooling methods. Vortex cooling can be simply made by changing the direction of propellant injection rather than conventional rocket propulsion cooling systems, such as regenerative cooling, film cooling, ablative cooling, and radiative cooling, which are potentially more complex and may require more system components to cool down combustion chambers and nozzles. The study investigates injection-related parameters and their impacts on thruster wall temperature and characteristic velocity efficiency. Operational parameters include O/F ratio, propellant mass flow rate, injection position, and combination of fuel and oxidizer injection types (5 different injection cases) to support the comparison analysis. Based on the experimental test results, it has been found that the vortex-cooled thruster can maintain an Acrylic chamber wall temperature and nozzle below 100°C, which is below the Acrylic melting point. The swirl injection resulted in the circulation of the oxidizer following the inner surface of the chamber, isolating the wall from the combustion reaction. The surface was thus kept away from the high-temperature flame during the operation. The study proves that thermoplastics can be safely cooled when swirl cooling is adopted. The cooling performance characteristics investigated through this work are expected to constitute a useful reference, conducive to a potential rocket engine entirely built using thermoplastic materials with various possible mission scenarios for interplanetary travels.