Advanced modeling of metallic rocket engine nozzle extensions and the performance impact of film cooling

A great effort has been made by the European space industry to ensure an innovative and independent progress in space technology. In this context The Exploration Company, which supported the present work, is rapidly developing new technologies for future space transportation systems, including a new LOX/CH4 liquid rocket engine named Huracán that will equip their future space module and lunar lander Nyx Moon. This thesis focuses on the nozzle extension of the Huracán engine. The nozzle extension is a vital component for a rocket engine with in-space applications. Its purpose is, indeed, to get the most thrust possible from the expansion of the hot gases in a near-vacuum environment. Although it is a thermally critical component, its design differs from that of the main combustion chamber due to the lower temperature of the expanding gases and the weight limitation that a large component such as the nozzle extension entails. In this work the flowfield behavior of the expanding gases in the nozzle extension has been investigated. An analytic model has been implemented to provide useful data for the future design of the component. The model has been compared to numerical solutions which include the most relevant phenomenon that characterize high temperature environments. Multiple cooling strategies have been investigated, with a focus on film cooling which is historically one of the most studied and than implemented cooling technologies for this kind of application. Finally, the performance impact of film cooling has been evaluated. The results of this thesis will provide useful data for the development of the nozzle extension and for future studies related to this component.