Imaging the reactive flow structure in shocked nitromethane and nitromethane with additives

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

doi:10.1063/12.0000910

Cited by 3 publications

(12 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The thin Al foil is used to make the lids have varying degrees of textures and scratches (Figure 1b), but in previous work, we showed that this had a minimal effect on the shocks and on the shock front images. 14 Optical measurements detect visible thermal emission from the ∼3500 K reactive flow. A 32-channel optical pyrometer 18 measures the spectral radiance in the 450−825 nm range every 0.8 ns with record lengths out to 2 ms.…”

Section: ■ Methodsmentioning

confidence: 99%

“…Images are recorded as an unformatted matrix and processed using MATLAB software to create TIF images. 14 An 8 GHz photon Doppler velocimeter (PDV) is used to measure material velocities associated with the shock input and the chemically sustained shock output. 16,17 The PDV interrogates a 0.1 mm diameter spot at the center of the shocked volume.…”

Section: ■ Methodsmentioning

confidence: 99%

“…We previously described how we synchronized the PDV with the flyer plate launch and the other optical diagnostics. 14,16 In Figure 1c, PDV measures the velocity of the inside surface of the Al lid, i.e., the Al/NM interface, giving the material velocity profile u p (t) imparted by the flyer plate to NM. 6 We define time t = 0 as the time PDV detects the first motion of the inner surface of the lid.…”

Section: ■ Methodsmentioning

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%

“…The NM reactive flow was probed by 2 ns photon Doppler velocimetry (PDV) 16,17 and by 5 ns video photography of the luminous shock front. 14 Nitromethane ignition and reaction temperatures were probed by 0.8 ns optical pyrometry. 18 PDV is used to measure the flow velocity imparted to NM by the high-speed impact as well as the velocity profile of the shock breakout into a window (witness plate) various distances downstream using a series of cuvettes of different thicknesses ranging from 30 to 250 μm.…”

Section: Ch Nomentioning

confidence: 99%

See 4 more Smart Citations

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

2021

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%