Thermal Decomposition of Hydrogen Peroxide, Part I: Experimental Results

Thermal decomposition is an important process in propulsion systems that use hydrogen peroxide (HP). Neither a combined vaporization-decomposition model nor a fundamental understanding of the way liquid HP vaporizes and decomposes in these rocket applications exist. Results are presented from an experimental study of the combined thermal decomposition of HP at rocket-type conditions. A liquid spray of HP is injected into a cross stream of HP decomposition products at chamber pressures ranging from 2.0 to over 5.5 MPa. Two injectors with different orifice diameters are used. Experimental parameters include flow rates of the decomposition products and liquid injectant, HP concentration, chamber geometry, and momentum ratio between the liquid injectant and the decomposition stream. A decomposition efficiency of the liquid HP is determined based on the ratio between measured chamber pressure and chamber pressure calculated by equilibrium chemistry. An analysis of the crossflow injection is used to assess the effects of spray trajectory. Decomposition efficiencies ranging between 10 and 90% were measured. The results show that decomposition efficiency is inversely proportional to the fractional amount of liquid injectant flow rate, linearly proportional to residence time, and that higher concentration HP decomposes at a faster rate.