Spatiotemporal Characterization of Large-scale Detonation Based Combustion of Reactive Metal-Gas Mixtures
Abstract
Approved for Public ReleaseDetonation-based combustion of metal particle-gas mixtures involves an extraordinarily diverse set of che mical reactions and physical processes occurring over a vast range of time and length scales that are not accessible to bench scale experiments. Because direct measurement of combusting reactive metals in turbulent detonating flows is extremely rare, our current u nderstanding of these rate controlling relationships is based on the simplified treatment of various interactions between burning pa rticles and detonation products extrapolated from small-scale tests.The objective of this experiment-driven research is to understan d the rate-controlled processes governing the large-scale e Virginia Tech Shock Tube Research Facility, equipped with the largest academic blast simulator in the United States. The main expe riment variables consist of the particle-gas mixture characteristics and the initiating detonation energy. Spherical aluminum partic les ranging from 1 to 100 microns in diameter, and in mass loads ranging from tens to hundreds of grams, will be subjected to gaseou s acetylene-oxygen detonation products. Due to the sheer size of the shock tube, energy release processes will be studied over multi ple distinct flow regimes, spanning initial detonation, post-detonation combustion, and far-field clean shock propagation. Multi-sit e sampling using combinations of different diagnostics will be used to spatiotemporally resolve the pressure, velocity, temperature, energy release, chemical species, and shock structure as the multiphase flow transverses these distinct regimes. Diagnostics includ e the simultaneous use of fiber optic probe arrays, Doppler radar, laser absorption spectroscopy, pressure transducers, and syntheti c schlieren to obtain measurements of the detonation parameters and the reaction kinetics. The large volume of experimental data wil l be processed and parameterized to enable the assessment of potential sources of uncertainties, as well as investigation of the spa tial and temporal heterogeneity of measured responses and energy release rates.Controlled detonation experiments have not previously been performed using: (1) the large-scale blast facilities needed to comprehensively and repeatably study detonation-based combusti on, (2) several different metal particle parameters and oxidizing conditions, and (3) the diverse variety and combination of diagnos tic techniques required to spatiotemporally resolve the flow. Thus, the experimental program will allow the correlation of particle- gas mixture characteristics to the detonation parameters and rate kinetics. The scientific outputs of this research will include new theories to describe the processes governing the detonation-driven energy release rates of aluminum particle combustion, described in terms of the bulk mixture characteristics, and how these processes can be tuned to precisely control the timescale over which par ticle-phase energy is deposited into the flow.This research will provide the DoD energetics community with direct and accurate measu rement of large- scale detonation-based combustion of particle-gas mixtures, as an enhancement over lab scale measurements that do n ot replicate the huge impact of the physics at larger scales. Improved spatiotemporally resolved datasets can then be used to develo p and validate high fidelity multiphase simulations to predict performance and behavior more accurately. Therefore, the scientific r ationale and strong relevance of the study to the DoD research enterprise will promote significant progress in controlling and desig ning advanced energetic materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2021
- Source ID
- N000142112777
Entities
People
- Eric Jacques
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech