Modeling a monolithic silicon carbide pintle rocket injector

A monolithic silicon carbide (SiC) pintle rocket injector is under development with the intent to be used in a liquid propellant micro-rocket engine. MATLAB code was developed to determine the rocket´s Thrust/Weight ratio, which is critical in maximizing a rocket´s efficiency. COMSOL finite element modeling has been used to develop two-dimensional turbulent flow models to simulate the velocity flows coming from the radial and axial orifices of the injector. Three-dimensional turbulent flow models were also developed to study the axial and radial flows independently. Using these models, the velocity of the flows through the axial and radial orifices were determined based on a given inlet pressure. Two designs were chosen for the axial chamber. Both designs were tested for the velocity flow speed and the uniformity of the flow through the axial ring. Based on these models a suitable inlet pressure was chosen and fed into a set of three-dimensional solid mechanics models to study the stresses in the injector walls. Models indicated significant stresses around the axial orifice, and this was drastically reduced by adding several columns to reinforce the axial fuel chamber of the injector with a minimal change of flow characteristics. These models will serve as a guide in the batch production of pintle injectors on a silicon substrate.