Gelled Monomethyl Hydrazine Hypergolic Droplet Investigation

摘要

This paper addresses the combustion behavior of a monomethyl hydrazine droplet gelled with both hydroxypropyl cellulose and fumed silica in an environment of gaseous nitrogen dioxide. All of the monomethyl hydrazine/ hydroxypropyl cellulose gel droplets displayed swelling and jetting that are typical for hydrocarbon gels with an organic gelling agent. Burning rates were measured for droplet diameters from 1.8 to 3.2 mm at two ambient pressures of 1.72 and 2.89 bar. It was found that the droplet burning rate is dependent on the droplet diameter similar to liquid monomethyl hydrazine. Over the investigated pressure range no dependence of the burning rate on pressure was found. The combustion of monomethyl hydrazine/hydroxypropyl gel was compared to monomethyl hydrazine/ tetraglyme to examine the difference between a highly viscous surface layer (tetraglyme) and a fairly rigid surface layer (hydroxypropyl). Droplets of monomethyl hydrazine and tetraglyme showed increasing swelling frequencies and volume fluctuations during combustion, whereas the monomethyl hydrazine/hydroxypropyl droplets exhibited a more constant burning history. The monomethyl hydrazine/silica gels showed a different combustion mechanism with the formation of a rigid silica structure, microexplosions, and up to a 50% reduction in droplet volume during combustion.