Characterization of moisture and water content on ignition and combustion of hypergolic propellants
Triethylamine borane (TEAB) and white fuming nitric acid (WFNA) is a promising hypergolic propellant combination being studied as an alternative to monomethylhydrazine (MMH) and red fuming nitric acid (RFNA) or dinitrogen tetroxide (NTO). Nitric acid and MMH are both known to be hygroscopic and their performance is affected by their water content. However, the effect of water on TEAB is yet to be determined. The goal of this research is to characterize the major consequences of water presence on the ignition and combustion performance of TEAB and to compare those results to MMH. To determine the effect of hygroscopic absorption, TEAB samples were put through accelerated aging in humid and dry environments. Along with the aged TEAB, neat TEAB and neat MMH were used in drop on pool tests with WFNA. The drop tests were conducted by controlling the relative humidity in air to either below 24% or above 94% and the water concentration in WFNA to either 0% or 10% by weight. Using the Hypertester, ignition and combustion events were recorded using a photodiode, a microphone, a high speed camera, and a UV streak camera spectrometer. A drop chamber was used to determine the time of gas production onset from the liquid phase reactions. Along with the dry and humid air environments, tests were done in a nitrogen environment in the drop chamber. MMH and RFNA drop tests in a nitrogen environment were completed to replicate the results of Forness. Statistical analysis is applied to the data to determine significant parameters and trends. While relative humidity does not appear to affect the combustion of TEAB with WFNA, water concentration in the oxidizer significantly weakens it. Relative humidity improves MMH ignition delay time and water concentration shows no effect. Water concentration in the oxidizer more than doubles the liquid induction time of both TEAB and MMH with WFNA. The ambient environment does not play a significant role in the onset time of gas production. Both WFNA and RFNA show the same liquid induction time when reacting with MMH. There is no correlation between the liquid induction time and the ignition delay time.
Pourpoint, Purdue University.
Inorganic chemistry|Aerospace engineering
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