Catalytically promoted green fuel with hydrogen peroxide: Effect of hypergolic combustion on atomization and flow characteristics using impinging jets

This study explores the jet impingement of a catalytically promoted hypergolic green fuel with High Test Peroxide (HTP). Experimental investigations were conducted using simultaneous high-speed visible, infrared and backlight imaging. Two major aspects were investigated. First, a study exploring the potential of decoupling the combustion phenomenon through the utilization of the fuel without a catalyst as a simulant, enabling a comparative analysis of the atomization process with the authentic hypergolic pair undergoing combustion. A Reynolds versus Weber numbers diagram was obtained for jets with equal momentum in the steady-state flow regime, and a novel breakup mode was observed. The named Reactive Foamy Segregation mode was found as a two phenomenological regime, where a reacting foam exists together with a segregation stream. An analysis of the liquid film velocity formed by impinging jets indicated that the hypergolic pair exhibited significantly lower speeds and corroborates with the introduced breakup mode. Second, an analysis about the transient and steady-state jet flow effects, revealing the existence of separate planes for the reacting foam and plumes, regions with different oxidizer to fuel ratios. This natural effect was intensified by the force generated from the exothermic reaction of hydrogen peroxide decomposition. Notably, the central region of the sheet exhibited the lowest temperature, indicating that the liquid -phase mixture and propellants' residence time were insufficiently effective in decomposing the peroxide. These findings contribute to a deeper understanding of the complex fluid dynamics involved in catalytically promoted hypergolic reactions applied in liquid rocket engines.