Session: 03-13-01: Testing and Characterization

Paper Number: 152216

152216 - Characterization and Computational Validation of Multi-Layer Carbon Fiber Based
Polymer Matrix Composite Material for Rocket Engine Combustion Chamber
Applications 

This paper presents the exploration of the usage of Carbon Fiber Reinforced Polymers (CFRP) in combustion chambers through the redesign of the Ragnar X [1] hybrid propulsion rocket engine, originally designed as part of the Uniandes Aerospace Project’s efforts in hybrid rocketry [2] [3]. The objective was to significantly improve the engine’s thrust-to-weight ratio, by replacing dense metal components with a lightweight carbon composite. However, the high-temperature environment of a rocket engine’s combustion chamber posed a significant challenge for the use of CFRP due to the matrix polymer’s thermal properties and resistance.

To address this challenge, the redesign incorporated a multi-layer composite structure, with a high temperature ceramic wool first layer acting as a thermal insulator that decreases the heat transfer through the polymer matrix. This insulation layer was critical in maintaining the temperature of the CFRP below its acceptable limit [<180°C] (experimentally determined) under the operating thermal conditions of the original engine. To properly determine the thermodynamic parameters for the combustion chamber during operation, a CFD simulation was carried out with the NASA CEArun combustion calculation software. Several resins were studied for this application, the selected formulation was implemented into a carbon fiber composite that was then characterized at different temperatures using the ASTM D3039 [4] method to establish its operating limit. The initial redesign was carried out using the mechanical properties established at ambient temperature (~18°C) and was later updated with the thermal based characterization at the acceptable limit [<180°C]. Additionally, a computational heat transfer simulation was employed using the thermodynamic properties obtained as well as the pressure and contact conditions. This simulation determines the temperature distribution of the composite material during the engine’s operation, validating the maximum timeframe within which it could function without a critical failure caused by loss of properties in the material. The results of this computational validation are that the combustion chamber supports engine operation with a safety factor of around 1.9 for a minimum 22 seconds.

The redesigned combustion chamber achieved a remarkable reduction in total mass from 10.7 kg (23.6 lb) to 5.91 kg (13.04 lb), this despite the having to accommodate for a significantly heavier nozzle (1.7 times heavier). The material’s total mass reduction resulted in a net weight decrease of 46.94 N (10.55 lbf). This is translated into a substantial improvement in the thrust-to-weight ratio, increasing by a factor of 1.81 from 8.58 in the original design to 15.52 in the redesigned engine, based on its theoretical 900 N of thrust. The integration of the insulating layer in the CFRP’s multi-composite structure did not negate the final mass reduction achieved by the change in material despite the ceramic wool layer constituting weight of material that sustains no load from the internal pressure of the combustion.

This project demonstrates through a particular case study in hybrid propulsion the potential of polymer matrix composites as an alternative to traditional metallic materials for combustion chambers when combined with a thermal insulator through replicable composite manufacturing methods (fabric lay-up), achieving significant weight reduction for experimental rocket engines. The research addresses the critical thermal challenge of using polymers in rocket combustion applications and provides robust validation through both experimental and computational methods for the proposed solution’s positive performance through the operational thermal conditions of a rocket engine’s combustion chamber.

References:

[1]          S. Prada, “Diseño conceptual de cohete experimental con motor de combustible híbrido N2O/ABS,” Universidad de Los Andes, Bogotá D.C, Colombia, 2021.

[2]          S. Prada, F. A. Rojas “Desarrollo de cohetes híbridos tipo sonda para potenciar la industria aeroespacial en Colombia.” ‘Congreso de Desarrollo Aeroespacial Colombiano’ (CODEAC), Medellin, Colombia, Oct. 2023.

[3]          J. A. Urrego P., F. A. Rojas “Combustion Performance Comparison of Propellant Grain for Hybrid Rocket Motors Manufactured by Casting and Fused Deposition Modeling.” International Journal of Mechanical Engineering and Robotics Research, Vol. 8, Issue 6, page 960, 2019.

[4]        ASTM, “Standard test method for tensile properties of polymer matrix composite materials,” D3039/D3039M 17, 2017.

Presenting Author: Santiago Gonzalez Buenaventura Universidad de Los Andes

Presenting Author Biography: Mechanical Engineering Graduate Student at Universidad de Los Andes in Bogota, Colombia. Focused on aerospace engineering and technology from a structural integrity and composite materials perspective.