Desarrollo de cámara de combustión liviana para cohetes de propulsión sólida.
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Date
2026
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Publisher
Universidad de Concepción
Abstract
El presente trabajo tiene como propósito evaluar la viabilidad termo-estructural y el potencial de reducción de masa para una cámara de combustión de Al 6061-T6 para el motor de propelente sólido Campanil desarrollado por el Grupo de Interés en Propulsión. La metodología integró la definición de condiciones operacionales, caracterización mecánica del material, modelos analíticos y numéricos, análisis térmico mediante FEM, prototipado, evaluación térmica experimental y un ensayo estático bajo quema interna. El aluminio seleccionado presentó un límite de fluencia de 234 MPa y una resistencia última de 251 MPa. Para la presión de diseño de 11 MPa, los modelos del cuerpo cilíndrico muestran un esfuerzo equivalente de aproximadamente 117 MPa con un factor de seguridad cercano a 2 en condiciones a temperatura ambiente. El análisis térmico mostró que una cámara de aluminio sin protección puede alcanzar fácilmente temperaturas críticas para sus propiedades mecánicas a partir de las severas condiciones de operación a las que se expone un motor de cohete. A partir de este procedimiento, se justificó la implementación de una protección térmica hecha en PVC. La cámara fabricada presentó una masa de 0.783 kg frente a 1.931 kg de la cámara original de A106, representando una reducción del 59% para el componente. Durante el ensayo estático se presentó una falla estructural localizada en el sistema de unión tobera y cámara, impidiendo completar la comparación experimental con la línea base. Debido a la pérdida parcial de información durante el evento, no fue posible determinar la presión máxima realmente alcanzada. El análisis post-ensayo, fundamentado por registros visuales, reconstrucción temporal y ensayos adaptados de uniones pasador-agujero, identificó el modo de falla de desgarramiento por corte como el modo predominante del diseño de la unión y evidenció la sensibilidad de la distribución de carga sobre la cámara gracias a los pernos. Además, se detectó un comportamiento anómalo en el desarrollo de la presión con un aumento cinco veces más rápido en comparación con los ensayos históricos, junto con un taponamiento parcial de tobera producto del sistema de iniciación. Estos resultados indicaron solicitudes mecánicas superiores a las definidas a partir de las condiciones de operación. Se concluye que el Al 6061-T6 mantiene un potencial relevante para mejorar el desempeño de un cohete a partir de la reducción de masa de la cámara, sin embargo, la configuración estudiada requiere rediseñarse antes de una nueva prueba con quema de propelente y se debe reducir la incertidumbre en el comportamiento del propelente junto al sistema de iniciación.
This work evaluates the thermostructural feasibility and mass reduction potential of an Al 6061-T6 combustion chamber for the solid propellant rocket motor Campanil developed by the Grupo de Interés en Propulsión at Universidad de Concepción. The methodology comprised the definition of operating conditions, mechanical characterization of the aluminum alloy, analytical and numerical modelling, transient thermal analysis, prototype manufacturing, thermal tests, and a static fire test. The experimental characterization of the aluminum yielded an estimated yield strength of 234 MPa and an ultimate tensile strength of 251 MPa. For a design pressure of 11 MPa, pressure vessel models of the aluminum tube predicted a Von Mises equivalent stress of 117 MPa and a safety factor of 2.0 at room temperature. The thermal analysis indicated that unprotected aluminum may undergo severe mechanical properties degradation when it is exposed to the high temperatures of combustion. An internal PVC barrier was therefore incorporated, and its thermal delay effect was supported by a comparative thermal test. The manufactured chamber had a mass of 0.783 kg, compared with 1.931 kg for the original A106 steel chamber, the new chamber had an approximate 59% mass reduction. During the static firing test, a localized structural failure occurred at the chamber-to-nozzle joint, preventing validation of the configuration and completing the experimental comparison with the baseline motor. Partial loss of measurements and ejected components prevented the determination of the actual peak pressure. Post-test analysis, supported by visual records, temporal reconstruction, pin-bearing tests, and sensitivity calculations identified shear tear-out as the predominant local failure mode and showed that the joint is highly sensitive to non-uniform load sharing among the bolts. In addition, an anomalous pressure evolution was identified, with a pressure rise approximately five times faster than that observed in previous static tests, together with evidence of partial nozzle blockage caused by the ignition system. These findings indicate that the motor was subjected to mechanical loads exceeding those established from the original operating conditions. The results of the investigation concluded that Al 6061-T6 remains a promising material for improving rocket performance through combustion chamber reduction; however, the joint configuration requires redesign and experimental verification before a new static firing test, while uncertainties associated with propellant behaviour and the ignition system must also be reduced.
This work evaluates the thermostructural feasibility and mass reduction potential of an Al 6061-T6 combustion chamber for the solid propellant rocket motor Campanil developed by the Grupo de Interés en Propulsión at Universidad de Concepción. The methodology comprised the definition of operating conditions, mechanical characterization of the aluminum alloy, analytical and numerical modelling, transient thermal analysis, prototype manufacturing, thermal tests, and a static fire test. The experimental characterization of the aluminum yielded an estimated yield strength of 234 MPa and an ultimate tensile strength of 251 MPa. For a design pressure of 11 MPa, pressure vessel models of the aluminum tube predicted a Von Mises equivalent stress of 117 MPa and a safety factor of 2.0 at room temperature. The thermal analysis indicated that unprotected aluminum may undergo severe mechanical properties degradation when it is exposed to the high temperatures of combustion. An internal PVC barrier was therefore incorporated, and its thermal delay effect was supported by a comparative thermal test. The manufactured chamber had a mass of 0.783 kg, compared with 1.931 kg for the original A106 steel chamber, the new chamber had an approximate 59% mass reduction. During the static firing test, a localized structural failure occurred at the chamber-to-nozzle joint, preventing validation of the configuration and completing the experimental comparison with the baseline motor. Partial loss of measurements and ejected components prevented the determination of the actual peak pressure. Post-test analysis, supported by visual records, temporal reconstruction, pin-bearing tests, and sensitivity calculations identified shear tear-out as the predominant local failure mode and showed that the joint is highly sensitive to non-uniform load sharing among the bolts. In addition, an anomalous pressure evolution was identified, with a pressure rise approximately five times faster than that observed in previous static tests, together with evidence of partial nozzle blockage caused by the ignition system. These findings indicate that the motor was subjected to mechanical loads exceeding those established from the original operating conditions. The results of the investigation concluded that Al 6061-T6 remains a promising material for improving rocket performance through combustion chamber reduction; however, the joint configuration requires redesign and experimental verification before a new static firing test, while uncertainties associated with propellant behaviour and the ignition system must also be reduced.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Aeroespacial.
Keywords
Cohetes (Aeronáutica), Motores cohete, Combustión