Shock-induced kinetics and cellular structures of liquid nitromethane detonation

Nissen, Erin J.; Bhowmick, Mithun; Dlott, Dana D.

doi:10.1016/j.combustflame.2020.10.046

Cited by 14 publications

(35 citation statements)

References 39 publications

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“…7 Experimental confirmation for this two-stage reaction includes studies of NM under high pressure ignited by a short-duration laser pulse 11 and the recent study of shock-todetonation in NM by our group. 7 The chemical mechanism of amine sensitization of NM shock ignition was studied by Gruzdkov and Gupta. 5 They measured the shock ignition threshold by detecting a rise in visible absorption presumably due to the formation of a condensate.…”

Section: ■ Introductionmentioning

confidence: 88%

“…Thus, it is possible to ignite the NM without producing a detonation. 7 It is well-known that the NM shock-to-detonation process involves the formation of the so-called "superdetonation". 1,12,13 In our recent experiments using 4 ns input shocks, we found that when a sufficiently strong shock enters NM, it produces a thermal explosion near the entry plane after a delay of a few nanoseconds.…”

Section: Ch Nomentioning

confidence: 99%

“…1,12,13 In our recent experiments using 4 ns input shocks, we found that when a sufficiently strong shock enters NM, it produces a thermal explosion near the entry plane after a delay of a few nanoseconds. 7 The delay is due to the endothermic reactions that precede the strongly exothermic reactions. By the time the thermal explosion occurs, the initiating shock, moving at about 6 μm/ns, is tens of micrometers downstream.…”

Section: Ch Nomentioning

confidence: 99%

“…The merge process must produce a shock strong enough to liberate energy from the condensate to enable the detonation to form. 6,7,14 In our studies of shock-to-detonation with a short-duration input shock, 6,7 we used overdriven shocks and a subcritical geometry to produce a detonation in record time. 6 The pressure of the input shock was adjusted so that the superdetonation pressure would be somewhat greater than the steady detonation pressure.…”

Section: Ch Nomentioning

confidence: 99%

“…15 Once a steady detonation is formed in subcritical geometry, it is quickly quenched by the arrival of radial rarefaction waves (edge waves). The overdriven subcritical method allows experimenters to observe the entire process of shock to detonation to decay with a run distance of ∼250 μm in <1 mg of NM, 6,7 which makes it possible to perform detailed studies of detonations on a tabletop. 6 Recently, we used 5 ns imaging to study the luminous shock and detonation front in NM.…”

Section: Ch Nomentioning

confidence: 99%

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Ethylenediamine Catalyzes Nitromethane Shock-to-Detonation in Two Distinct Ways

2021

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Adding amines to liquid nitromethane (NM) is known to lower the threshold for the shock-to-detonation transition because amines catalyze proton transfer reactions that are the initial steps in the energy release process. We studied NM with 1 wt % ethylenediamine (NM/EDA) with 4 ns input shocks using time and space resolved diagnostics: photon Doppler velocimetry (PDV), optical pyrometry, and nanosecond video imaging. The 4 ns shocks are fast enough to time-resolve the reaction kinetics and the shock-to-detonation transition. We find that it is possible to shock ignite the NM/EDA without producing a detonation, so there is more to amine sensitization of the shock-to-detonation process than simply lowering the barrier to initial reactions. We find that although 1 wt % EDA has little effect on the ambient properties of NM, it dramatically alters the Hugoniot. The shock speed in NM/EDA is reduced, indicating that shocked NM/EDA is significantly more compressible than NM. Higher compressibility is associated with greater adiabatic heating, so EDA both lowers the barrier to proton transfer reactions and increases shock energy absorption. To explain the enhanced compressibility, we propose that shocking NM/EDA produces a reactive flow that has a much higher ionic strength than in NM. The sudden transformation from a molecular liquid to an ionic liquid with stronger intermolecular interactions is responsible for enhanced compressibility and shock heating.

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