Effect of Water and Humidity on Hypergolic Propellant Ignition Delay

Abstract

Triethylamine borane (TEAB) and white fuming nitric acid (WFNA) is a promising hypergolic propellant combination being studied as an alternative to monomethyl hydrazine (MMH) and red fuming nitric acid (RFNA). 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. TEAB samples are put through accelerated aging in humid and dry environments. Along with the aged TEAB, neat TEAB and neat MMH are used in drop on pool tests with WFNA. The drop tests are conducted by controlling the relative humidity to either below 25% or above 90% and the water concentration in WFNA to either 0% or 10% by weight. Ignition and combustion events are recorded using a photodiode, a microphone, a high speed camera, and a UV streak camera spectrometer. 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. Nomenclature c* = characteristic velocity IDT = ignition delay time I sp = specific impulse MMH = monomethylhydrazine NTO = dinitrogen tetroxide PTFE = polytetrafluoroethylene RFNA = red fuming nitric acid RH = relative humidity TEAB = triethylamine borane WFNA = white fuming nitric acid = expansion area ratio  = density

Thermal Explosion Experiment of Energetic Materials

“…Combined with the results of experiment and simulation, the effects of different environmental temperature ignition location and reaction intensity of grain are discussed. Zhan Zhibo [20,21] conducted thermal explosion experiment using the device self-designed, test method and humidifier humidity control reaction, the thermal explosion experiments of single base propellant. The experiment explores the effects of temperature and humidity on the self-ignition of propellant.…”

Evaluation of the possibilities of adapting a constant volume combustion chamber for research on ignition of hypergolic propellants under low and high-pressure conditions

“…In order to more accurately capture the instant of contact of a falling drop with the pool and time of ignition, additional equipment can be utilized, e.g. pressure sensors, photodiodes [18].…”