Laser Ignition of Solid Propellants Using Energetic nAl-PVDF Optical Sensitizers

Uhlenhake, Kyle E.; Collard, Diane; Gomez, Mateo; Örnek, Metin; Son, Steven F.

doi:10.2514/6.2022-1744

Cited by 4 publications

(2 citation statements)

References 28 publications

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“…Therefore, optical absorption of a specific material is significant for its laser ignition, which was also shown by the work on the Laser Ignition in Guns, Howitzers and Tanks (LIGHT) [6]. More recently, laser ignition method was experimentally investigated by using energetic nano-aluminium (n-Al) and polyvinylidene fluoride (PVDF) particles as optical sensitizer and sustained ignition of ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) composite propellants was achieved with relatively low laser energy levels (less than5 J/cm 2 ) [7]. Pentaerythritol tetranitrate (PETN) and RDX were studied for their ignition with aluminium nano-powder as an optical sensitiser by a pulsed neodymium laser [8].…”

Section: Introductionmentioning

confidence: 99%

Optical sensitising of insensitive energetic material for laser ignition

Fang

Walton²

2023

Optics & Laser Technology

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Section: Introductionmentioning

confidence: 99%

Optical sensitising of insensitive energetic material for laser ignition

Fang

Walton²

2023

Optics & Laser Technology

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“…A wide variety of fluoropolymers such as PVDF, Viton, THV, and PMF have been tested with aluminum to study their effect on burn rate, flame temperature, gas release, and agglomeration reduction [5,8,[10][11][12]22]. Ignition studies have shown that dense nAl/PVDF or a porous composite of Al/PVDF enables flash and laser ignition of other composites [14,23,24].…”

Section: Introductionmentioning

confidence: 99%

Additively Manufactured Micro‐ and Nano‐ Al/PVDF Ignition Sensitivity and Burning Characterization

Uhlenhake

Collard

Hoganson

et al. 2023

Propellants Explo Pyrotec

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Aluminum (Al) and polyvinylidene fluoride (PVDF) composites can be used in many unique applications in the field of energetic materials. Due to their low melting point, many PVDF composites can be additively manufactured. However, more research is needed to better understand the ignition and combustion of these materials. Manipulating the size of aluminum (Al) particles in Al/PVDF composites can drastically alter the burning rate, ignition characteristics, and possibly flame temperatures. This study characterizes the ignition of additively manufactured microand nano-Al/PVDF composites through hotwire ignition tests. Both nAl and μAl particles were mixed in PVDF at 20 wt.% and additively manufactured into disks via fused filament fabrication. The nAl/PVDF printed disks ignited at a minimum ignition power (MIP) of 4.1 W compared to the 9.5 W required for ignition of μAl/PVDF disks. At identical powers, ignition delays were significantly shorter for nAl/ PVDF disks. Additionally, while the nAl/PVDF disks reacted instantaneously at any power above their MIP, the μAl/ PVDF disks exhibited smaller, localized flames before complete combustion, if the power was below 17.5 W. Flame temperatures were estimated through three-color pyrometry and compared to thermochemical equilibrium calculations. While theoretical flame temperatures for nAl/ PVDF and μAl/PVDF are 2023 K and 2314 K respectively, both samples burned near 2000 K when measured using pyrometry.

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Dielectric breakdown driven by flexoelectric and piezoelectric charge generation as hotspot ignition mechanism in aluminized fluoropolymer films

Shin

Messer

Örnek

et al. 2022

Journal of Applied Physics

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Using multiphysics simulations and experiments, we demonstrate that dielectric breakdown due to electric charge accumulation can lead to sufficient hotspot development leading to the initiation of chemical reactions in P(VDF-TrFE)/nAl films comprising a poly(vinylidene fluoride-co-trifluoroethylene) binder and nano-aluminum particles. The electric field ( E-field) development in the material is driven by the flexoelectric and piezoelectric responses of the polymer binder to mechanical loading. A two-step sequential multi-timescale and multi-physics framework for explicit microscale computational simulations of experiments is developed and used. First, the mechanically driven E-field development is analyzed using a fully coupled mechanical–electrostatic model over the microsecond timescale. Subsequently, the transient dielectric breakdown process is analyzed using a thermal–electrodynamic model over the nanosecond timescale. The temperature field resulting from the breakdown is analyzed to establish the hotspot conditions for the onset of self-sustained chemical reactions. The results demonstrate that temperatures well above the ignition temperatures can be generated. Both experiments and analyses show that flexoelectricity plays a primary role and piezoelectricity plays a secondary role. In particular, the time to ignition and the time to pre-ignition reactions of poled films (possessing both piezoelectricity and flexoelectricity) are ∼10% shorter than those of unpoled films (possessing only flexoelectricity).

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Laser Ignition of Solid Propellants Using Energetic nAl-PVDF Optical Sensitizers

Cited by 4 publications

References 28 publications

Optical sensitising of insensitive energetic material for laser ignition

Optical sensitising of insensitive energetic material for laser ignition

Additively Manufactured Micro‐ and Nano‐ Al/PVDF Ignition Sensitivity and Burning Characterization

Dielectric breakdown driven by flexoelectric and piezoelectric charge generation as hotspot ignition mechanism in aluminized fluoropolymer films

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