Parametric study of the fluid behaviour in a simplified Vortex-Cooled Rocket Engine through numerical simulations

Abstract

Humans have always looked at the heavens and wondered about the nature of the objects seen in the night sky. Discovering the secrets of space has been and is one of humanity’s greatest desires, however, each rocket launch involves a great economic cost. With the development of lighter rockets and the advances in electronics and other technologies in the 20th century, it became possible to lower costs and make rocket launches a common practice. Several methods to reduce the weight of the rockets have been proposed. This document is based on the Vortex-Cooling technique, a variant of film cooling which aims to cool the walls of the combustion chamber by means of a vortex flow in order to reduce its thickness. The main objective is to study the flow behavior of such a simplified vortex-cooled rocket engine in different configurations through numerical simulations. Firstly, a 3D model of Rocketdyne RS-25 (SSME) geometry is created from data sheets published by NASA. Besides, six different geometries of vortex-cooled rocket engines (VCRE) have been 3D modeled in order to carry out four analyses. Secondly, the characteristics of the mesh, a turbulent model for high-velocity flows, as well as the boundary conditions and all the parameters that allow computing the simulations of the SSME and vortex-cooled rocket engine have been selected. Using computational fluid dynamics (CFD) studies on the SSME it has been possible to verify the simulations obtained with Ansys Fluent. Once the parameters used in Fluent have been verified, it is proceeded to compute the simulations of 8 VCRE, modifying the number of inlets that generate the vortex; the angle of incidence of the inlets with respect to the axial direction; the diameter of the inlets; and finally, inlet velocity. After drawing conclusions from each analysis, the VCRE configuration chosen among the 8 cases studied is presented in more detail. The choice is based on the characteristics of the generated vortex, being the one that best meets the purpose of the vortex cooling technique. Comparing this rocket engine with the SSME, an 83% reduction of the flow temperature in the combustion chamber wall stands out. Nevertheless, apart from temperature, results are presented for other physical properties of the flow, such as velocity and pressure.