A Tale of Two Flames

I haven’t posted in awhile, so here’s a lit review.

The decomposition and oxidation of hydrazine has been a topic of scientific interest for at least eighty years. Early studies, such as those by Askey or Bamford, focused on the vapor phase. Bamford noted that the chemical exploded when sparked or heated.
Audrieth noted much interest in low-concentration (~30%) hydrazine as a fuel in the years after World War II, writing that, “The hydrogen peroxide-hydrazine combination was first utilized by the Germans as a rocket fuel and represents one  of the most promising bi-fuels for long-range high-altitude missiles.” He also documented that this combination appeared to be “self-starting”. In the same year, 1951, a paper by Murray and Hall recorded the observation of a 93% hydrazine flame. They described “possibly two inner cones, separated from one another by a very small distance.” This is extremely interesting to note in light of the dual-flame phenomena for droplets, although the authors attributed the second cone to “radiation from reaction products”. Continue reading

Fuel

Monomethyl hydrazine is based on hydrazine, which has the chemical formula N2H4. Hydrazine is also used as a propellant and is both unstable and toxic. It may be used as monopropellant (usually after being run through an appropriate catalyst bed), or more commonly as a bipropellant, being hypergolic with nitrogen tetroxide (NTO). Applications of hydrazine have included propelling the Me163B (the first rocket-powered fighter, WWII), on the Viking and Phoenix lander descent engines, and powering F-16 emergency power units. Notably, the thrusters on the spy satellite USA 193 were fueled with hydrazine; an interesting article on the role of hydrazine in the satellite shootdown is here: http://spectrum.ieee.org/aerospace/satellites/us-satellite-shootdown-the-inside-story

Monomethyl hydrazine (MMH) is the result of replacing one of the hydrogens in hydrazine with a methyl group, CH3. It is more stable than hydrazine (can be used in regeneratively cooled engines), and is thus favored as a storable propellant. Because it is still toxic, as well as a suspected carcinogen, great care is taken in handling it. It is most commonly used in hypergolic combination with NTO, such as in the Space Shuttle’s Reaction Control System (thrusters). MMH decomposes into mainly H2, with some CH4, N2, and trace amounts of NH3 and C (soot).

Beginning a Long Explanation

“First of all,” my sister writes, “you should post on what your project is/is trying to accomplish.” … All right, my objective: Characterize the behavior of dual flame fronts in gelled MMH/gaseous NTO as NTO diluent partial pressure and type vary.

This is the simplest way to summarize my project while still preserving the technical aspect. It does, however, lead to a slew of questions: What is involved in “characterizing”? What is a dual flame front? What do MMH and NTO stand for and what are they? Why would you gel them? Why is diluent involved and what am I using? And how does this help babies in Africa?

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The Plan

Summer is here! Last summer I tried to step up my posts to once a week, writing on topics suggested by you, my beloved readers. I’m inclined to be less democratic this year. Who cares for the whims of the general populace? I have a thesis to write – and this blog is going to help me. At least, that’s the plan.

Hold me to it: one post per week on some topic related to what I need to cover in my thesis. It will have to be pretty high-level, but at least I’ll be generating content that I can use in some fashion, and it’ll make me think about the “bigger picture”.

If you do feel the dire need to request a post on something, I might be able to satisfy your search for information. We’ll see.

Speaking of thes(es?), this is great: [preface]

Sometimes a scream is better than a thesis.” -Manfred Eigen

Rocket Science, or What I Do at “Work”

Below are some photos from a typical testing day. This is mainly for my family or other people who wonder what I’m doing when I say, “I have to go to work”, or, “I got to make fire yesterday.”

The dry box: actually stocks invented for chemists. It allows us to maintain a nitrogen environment for things that don't like oxygen.

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Deep Breath

Eyyyy…. I’m posting! (The almost-two months between this and the previous post are a mute, but powerful, witness to the onslaught of the semester.) Three big news items for right now: Research (!!!!) , knee surgery, and car.

Many of my parent’s supporters/family friends/other friends and family have been praying with me as I went through the submission of a research proposal to NASA in February, and then waited for the grant decision to come back. I finally heard their decision in August; I hadn’t gotten the grant, and therefore needed to find another thesis topic, and probably funding as well. Fortunately my teaching assistantship from last year had been renewed, so at least there would be a way to pay the rent. In the first weeks of the semester, I talked to a professor, who had a possible computational project, and also to my advisor, who offered a data analysis project. I wasn’t superexcited about either, since my goal in coming to Purdue had been to do an experimental research thesis. After reading a few papers on the topic I went in to talk to my advisor, who then said something along the lines of “So… I’ve been looking at the budget, and … would you like to do experimental research? It’s with toxic, probably carcinogenic, propellants, so you might die, but it could be interesting.”

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