Multi-Scale Methods to Simulate Detonation and Deflagration in High Density Propellants
Abstract
Executive Summary Energetic materials release their stored chemical energy through both de agration and detonation processes. New types of high-energy density materials (HEDM) and high-energy dense oxidizers (HEDO) are being investigated for both propulsion and ordnance applications using experiments and rst principle simulations. These studies provide insight into the characteristics of these materials at the atomistic level but scale up studies are typically limited to micro-scale samples under speci c conditions. To further evaluate performance and sensitivity much larger scale studies are warranted, especially since such energetic materials are also used as propellants. Modeling strategy that can capture the subtle sensitivity of the propellant micro-structure under shock impacts and/or de agration and can be used for scale-up studies requires a multi-scale capability since such heterogeneous systems contain void, cracks etc. over a wide range of scales. Simulation of these heterogeneous systems in the past have resorted to ad hoc tuning to match data. The current e ort focusses on a strategy that anchors all needed inputs to rst principle simulations at the atomistic level and then predicts performance that is compared to experimental data. The methodology as a result is computationally self consistent with very few ad hoc parameters but is more expensive to execute. However, e cient programming and massivelly parallel processing mitigate some of these overheads. The proposed e ort will exploit a recently developed (under ONE support) multi-scale method that incorporates a unique peridynamics based subgrid model that is anchored using data from rst principle atomistic simulations and therefore, does not require ad hoc tuning. This subgrid model is then used to provide a closure within the macro-scale simulation of detonation of condensed phase energetic materials under shock impacts. Results are shown to match experimental predictions when certain micro-scale features (e.g., hot spots) are included. Additionally, the formulation is shown capable of capturing shock-to-detonation transition (SDT) in energetic material even when the sample is placed in ambient air resulting in a true multi-scale prediction of solid-gas coupling. We propose to further extend this capability and also include uncertainty quanti cation (UQ) using surrogate models to further re ne and quantify the accuracy of macro-scale predictions when using the inputs from atomistic simulations. In addition to SDT studies for various energetic materials and its UQ analysis, the same multi-scale model will be used to simulate de agration as in sustained combustion of a propel- lant in a solid rocket motor. This is possible since the methodology is general and explicitly designed to address both de agration and detonation. However, for de agration studies we will focus on capturing surface burning and near-surface ame-turbulence interactions, and couple it to the macro-scale simulation of the background ow eld. Some enhancement of existing capabilities will be needed to ensure e cient simulations (such as preconditioning to increase time-step restrictions in the interface region) and will be resolved in this e ort. Even more novel is the potential of this approach to simulate events when a burning pro- pellant is impacted by a shock and/or sudden catastrophic events that can impact delivery systems. Detonation of energetic material while undergoing de agration has to the best of our knowledge never been simulated. Simulating and evaluating performance and sensitivity characteristics of such energetic materials before detailed experiments are conducted o ers a new cost e ective approach that can enable new focused strategies of Naval interest.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 03, 2016
- Source ID
- N000141612060
Entities
People
- Suresh Menon
Organizations
- Georgia Tech Research Corporation
- Office of Naval Research
- United States Navy