Thermal Analysis of a Hybrid Rocket Motor's Aft-End

In the next years, the space market forecasts un up-swell demand of small satellites which are traditionally delivered as piggyback payloads on rockets commissioned for larger spacecraft. For this kind of launch the primary payload takes priority imposing constraints on secondary payloads that have to be adapted to the launch schedule and orbit. In this scenario, private investors are now demanding for tailored services guaranteeing control over mission requirements, schedule reliability, and affordable launch opportunities to achieve a higher mission performance. Since new cost-effective and dedicated launchers have become mandatory, HyImpulse Technologies GmbH start-up has been founded to pursue the development of a hybrid rocket engine, in cooperation with the German Aerospace Center DLR in Lampoldshausen, in order to advance hybrid launcher technology. The hybrid system is more reliable, safer to be produced and stored, and ecologically friendlier then its solid or liquid counterpart at a reasonable price if some technological measures are taken to alleviate the combustion inefficiencies and boost the performance. In the design process the CAE implementation has been a major reason for start-up companies to be competitive in the engineering market leading to significant improvement in cost and time saving during the product development process since multiple physical problems can be simulated through the virtual environment without any material cost. One of the simulation software employed by HyImpulse is ANSYS) Workbench 19 which is a tool comprehensive of a wide range of analysis, among them the ANSYS transient thermal tool, which makes use of the finite elements method (FEM). The aim of the present work is the set-up of ANSYS transient thermal analysis, a simulation software, to estimate the temperature gradient along the thickness of an hybrid aft-end motor that includes the post-combustion chamber and the nozzle. Chapters introducing the theory under the simulating tool are presented in order to have a better understanding of the results and the competence to prove their correctness. Then a verification and validation is performed on the aft-end motor. To evaluate the temperature profile a parallel work with my colleague Giorgia is conducted: the CFD study of the internal steady- flow is necessary to set the internal loads of the structure whose temperature wall are necessary to set the CFD boundary conditions. With the set up of the validation case a parametric analysis is conducted to investigate two different material insulator and whose results are derived for two geometrical configurations, with and without a mixer. Temperature profile and peak is investigated for different combustion time and thickness length. This thermal investigation is the first step for a future and comprehensive structure stress analysis because an important requirement is to assure the integrity of the external structure of the aft-end motor whose structural limits are compared with the stress inside the structure. The stresses are caused by both thermal and pressure loads, but in this thesis only thermal evolution is studied.