Validação de metodologia numérica para auxílio em projetos de motores foguete

Abstract

The goals of this work aim to develop a numeric simulation of a compressible flow field in a rocket engine chamber and exit nozzle without chemical reaction with emphasis on studying the convergent-divergent using OpenFOAM software. The nozzle intern field allows the fluid to accelerate from subsonic speeds to supersonic speeds, a regime in which the “rhoCentralFoam” numerical code, used in the present work, is capable of dealing with different Mach numbers, where the discretization of the convective term occurs through “ Central-Upwind” by Kurganov and Tadmor. Through a general case available on the NASA website of a convergent-divergent nozzle, with the explicit objective of validating CFD codes, it was possible to carry out verification tests with three different flows, where the pressure in the combustion chamber is fixed and varies the pressure at the outlet. For this purpose, spatial discretization is necessary, carried out using the Salome-Meca program, in this case, structured meshes were employed, whose topology is composed of quadrilaterals in each element has always the same number of neighboring elements. After the simulation, it was possible to compare the results with the analytical data provided, which showed a satisfactory approximation, although there were divergences in some points with shock waves. Then, to perform the simulation of a small rocket engine that comes closest to real conditions, the PROPEP program is used to find the thermophysical characteristics of the KNSU propellant as well as obtain the stoichiometric combustion equation. A thrust of 67.58 N was obtained with only 8.54% of difference from the experimental tests developed from a subsonic regime (Mach = 0.089) to supersonic (Mach = 3.276), proving the code’s ability to simulate regimes in a wide range of speeds.