Numerical Study on Post-Combustion Chamber Impact on Hybrid Rocket Performance

Abstract

In chemical propulsion, propellant masses are generally the largest part of the overall weight. Hence, combustion efficiency is a key aspect of the system’s performance and small improvements within the combustion process can result in significant changes in project costs or mission longevity. To analyze detailed chemical and physical processes, direct measurements are cost-intensive and limited to lab–scale devices. Numerical investigations have therefore become a widely used tool to simulate the inner flow and combustion of propulsion systems. In hybrid rocket engines, post–combustion chambers are used to improve the mixing and combustion process. Nevertheless, these components imply additional structural mass and engine length. This study analyzes the influence of different post-combustion chamber lengths on the combustion efficiency. The simulations were performed in two–dimensional, axisymmetric domains with fuel mass flow and detailed combustion modeling. The efficiency is shown to increase linearly with increasing post–chamber length. However, it is significantly influenced by turbulator components. With these results, the qualitative influence of post– combustion chambers is analyzed, enabling optimization of engine design while ensuring sufficient combustion efficiency.