Finite Element Analysis for Rocket Motor Case Under Internal Pressure and Thermal Loads

Abstract

Rocket motor combustion chamber need to contain very high pressure and temperature due to burning of rocket fuels. Although for small rocket the burning time in the combustion chamber are short about 1 to 5 seconds it is very important to make sure that the combustion chamber can hold the pressure and heat produced by the burning of the fuels. Even with a very strong material of combustion chamber and the analysis proof that the chamber is able to stand the high pressure produced there are high probability of structural failure due to the increase of temperature due to heat into the combustion chamber wall since the increasing temperature of the combustion chamber wall will decrease the strength of the material. In this study the thermal analysis was done using ANSYS software with various thickness from CC 2.5, CC 3.5 and C.C 5.0 in two condition which are the stress due to static stress and the stress due to static stress and thermal stress. The propellant properties, pressure applied, chamber temperature and heat coefficient are the same in all cases. Then the results for the different thickness stress at the wall are plotted and compared. The study shows that the results due to then static stress and overall stress with different combustion chamber thickness for the radial stress show no significant differences. While the hoop stress and von-Mises stress due to static stress are maximum at inner wall and decrease as the direction of the wall increase from the inside. In other cases where the static and thermal stress are applied, the highest stress is at the outer wall of the cylinder. The higher combustion chamber thickness, the lower hoop stress and von-Mises stress need applied to the combustion chamber wall. Thus, results in higher safety factor for the higher combustion chamber thickness.