Parallel packing code for propellant microstructure analysis

Abstract

Please cite this article in press as: A. Baietta, F. Maggi, Parallel packing code for propellant microstructure analysis, Aerosp. Sci. Technol. (2015), http://dx.doi.org/10.1016/j.ast. 2015.08.012 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Parallel AbstractIn recent years, packing codes have become a successful alternative to experimental data collection for microstructure investigation of heterogeneous materials. Composite solid rocket propellants are interesting representatives of this category, consisting of a mix of fuel and oxidizer powders embedded in a polymeric binder. Their macroscopic properties are strictly dependent on the peculiar microstructure, which influences mechanical, combustion, as well as physical features. This work addresses algorithm development, validation, and scalability of POLIPack, a parallel packing code based on the Lubachevsky-Stillinger algorithm, developed at the Space Propulsion Laboratory (SPLab) of Politecnico di Milano. The application can reproduce the organization of spheres of any diameter inside a cube with periodic boundary. In addition to the general code description, the paper identifies a collision condition not addressed by the original Lubachevsky's algorithm (here called back impact), introduces a novel post-impact handling granting a minimum separation velocity between particles, and presents a parallelization approach based on OpenMP shared memory paradigm. Monomodal and bimodal packs have been compared to experimental data through statistic descriptors and packing maps.

Use of X‐Ray Computed Tomography for Validation of Random Packs of Composite Solid Propellants

“…The coarse and fine particles have darker and lighter shade of grey, respectively. The generated propellant packs are similar to the propellant packs obtained by earlier researchers [2][3][4][5][6][7][8]. Table 2 presents a comparison of the theoretical and measured densities of the propellant sample and the density of the simulated propellant pack obtained by the random packing algorithm.…”

“…Solid propellant modelling has made steady progress over the last few decades. Computationally generated three dimensional propellant packs have been used to study propellant combustion by several researchers [2][3][4][5][6][7][8]. Ramakrishna et al [4] have attempted a statistical comparison between generated propellant packs and an actual propel-lant.…”

“…Further, Maggi et al [7] devised an improved algorithm to generate propellant packs, an improvement over the method presented by Kochevets et al [5]. Recently, Baietta and Maggi [8] presented a study on parallel programming to generate propellant packs. All the above methods, barring [6], have compared their results with previously published experimental studies by researchers on sphere packing [10][11][12].…”