<p>A variety of methods have been
developed to enhance solid propellant burning rates, including adjusting
oxidizer particle size, modifying metal additives, tailoring the propellant
core geometry, and adding catalysts or wires. Fully consumable reactive wires
embedded in propellant have been used to increase the burning rate by
increasing the surface area; however, the manufacture of propellant grains and
the observation of geometric effects with reactive components has been
restricted by traditional manufacturing and viewing methods. In this work, a
printable reactive filament was developed that is tailorable to a number of use
cases spanning reactive fibers to photosensitive igniters. The filament employs
aluminum fuel within a printable polyvinylidene fluoride matrix that can be
tailored to a desired burning rate through stoichiometry or aluminum fuel configuration
such as particle size and modified aluminum composites. The material is
printable with fused filament fabrication, enabling access to more complex
geometries such as spirals and branches that are inaccessible to traditionally
cast reactive materials. However, additively manufacturing the reactive
fluoropolymer and propellant together comes attendant with many challenges
given the significantly different physical properties, particularly regarding adhesion.
To circumvent the challenges posed by multiple printing techniques required for
such dissimilar materials, the reactive fluoropolymer was included within a solid
propellant carrier matrix as small fibers. The fibers were varied in aspect
ratio (AR) and orientation, with aspect ratios greater than one exhibiting a
self-alignment behavior in concordance with the prescribed extrusion direction.
The effective burning rate of the propellant was improved nearly twofold with
10 wt.% reactive fibers with an AR of 7 and vertical orientation. </p>
<p>The reactive wires and fibers in
propellant proved difficult to image in realistic sample designs, given that
traditional visible imaging techniques restrict the location and dimensions of the
reactive wire due to the necessity of an intrusive window next to the wire, a
single-view dynamic X-ray imaging technique was employed to analyze the
evolution of the internal burning profile of propellant cast with embedded
additively manufacture reactive components. To image complex branching
geometries and propellant with multiple reactive components stacked within the
same line of sight, the dynamic X-ray imaging technique was expanded to two
views. Topographic reconstructions of propellants with multiple reactive fibers
showed the evolution of the burning surface enhanced by the geometric effects
caused by the faster burning fibers. These dual-view reconstructions provide a
method for accurate quantitative analysis of volumetric burning rates that can
improve the accessibility and viability of novel propellant grain designs.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/15060369 |
| Date | 27 July 2021 |
| Creators | Diane Collard (11189886) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Enhancing_Solid_Propellants_with_Additively_Manufactured_Reactive_Components_and_Modified_Aluminum_Particles/15060369 |
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