This research, conducted in collaboration with Isar Aerospace SE, presents a heat transfer analysis on a single-element LOx/Propane subscale rocket combustor with reactive-film cooling. The work aims to firstly reconstruct the time/space-resolved wall heat flux distribution using an inverse method, and secondly to analyze how operating parameters influence the thermal loads.
A series of hot-fire experiments were conducted in a capacitively and film-cooled copper subscale chamber, instrumented with thermocouples in multiple axial and azimuthal locations to capture the thermal response. A solver called Roq¤FITT was used to compute the heat flux profiles from temperature measurements, by coupling a transient conduction model with an iterative Jacobian-based optimization loop.
The analysis was focused on the throat region, where thermal stress peaks, and relied on visual graphs and statistical tools. Although a strong collinearity between chamber pressure and film ratio emerged, highlighting the limitation of the experimental set-up to fully isolate the contribution of all variables, meaningful trends emerged. Among them are correlations between heat loads and both chamber pressure and pressure instabilities, as well as an optimal film ratio configuration with minimized heat flux.
By computing the wall heat flux from internal temperature measurements, the study provides thermal insight into combustion-driven heat loading without the need to directly model the complex chemical and turbulent flow dynamics occurring inside the chamber. The obtained results form a valuable foundation for further design decisions on regeneratively cooled chambers and multi-element injector configurations, using the innovative LOx/Propane propellant combination.