Experimental Campaign and Numerical Modelling of a Liquid Oxygen Cooling System for a Hybrid Rocket

In this work, a regenerative cooling system for a hybrid rocket engine of 300 N thrust was tested and numerically simulated. The tests were run in the Space System Laboratory of Hokkaido University in Japan, using a combination of liquid oxygen and HDPE (high-density polyethylene). The cooling system consists of 3 helicoidal channels using the oxidizer as a coolant to avoid graphite nozzle erosion. The numerical model developed in ANSYS - fluent, is based on an iterative process using a 3D simulation of the cooling channels and a 2D simulation of the nozzle's wall. In particular, an empirical relation was extrapolated from the experimental data to estimate the average number of bubbles formed in the channels. The model was confirmed to be predictive, matching the nozzle's observed temperatures and heat fluxes within acceptable error limits. Moreover, the two-phase flow averaged parameters were successfully estimated. The nozzle did not experience erosion during the static fire tests, confirming the cooling system's effectiveness.