On the design and optimization of rocket nozzles based on the method of characteristics

Tiago Bischoff Fernandes

Key information

Authors:

Tiago Bischoff Fernandes (Tiago Bischoff Fernandes)

Supervisors:

Frederico José Prata Rente Reis Afonso (Frederico Afonso); Alain de Souza (Alain de Souza)

Published in

November 28, 2022

Abstract

Design optimization applied to rocket nozzles has been well-documented since the 1950s, gaining significant importance with the development of Computational Fluid Dynamics (CFD). However, with technological advancement comes an increase in computational requirements, which are not widely available. The present work aims to develop a low-fidelity and computational-friendly method to conduct nozzle shape optimization at a preliminary design phase of a rocket nozzle. With this in mind, a two-dimensional Method of Characteristics (MoC) is implemented as the foundation for the development of a flow simulation algorithm. Automating the contouring of various nozzle geometries through the popular parameterization technique of Free Form Deformation, an optimization process is established to maximize the performance of the nozzle. To verify the reliability of the proposed method, a similar optimization process is executed, established on high-fidelity CFD simulations using the open-source framework SU2 . An Euler solver is appointed instead of using RANS for the sake of similarity between both processes. This latter optimization process is established as a Surrogate-Based Optimization (SBO) not only to mitigate the SU2 framework limitations in performing CFD-based shape optimization on nozzles but also as a way to reduce the computational power. A good agreement between the results from both methods is achieved, displaying solely a small offset concerning the optimal contour width and the coefficient of thrust. Thus, proving the usefulness of developed aerodynamic shape optimization strategy based on the MoC for the preliminary design of nozzles.