This project proposes a significant contribution for the improvement of explosive and propulsive energy systems. Major advances will be proposed on the two following axes: - Optimization of materials and designed systems, - Prediction capacity of composition of energetic materials and system design under current and future environmental constraints. To do so, the three following items will be combined: - The scientific expertise of the project academic partners, expertise acquired during several decades in the modelling of reactive media based on solid fuels, - The design capability of safe propulsive and explosive energy systems with solid-phase or condensed materials, know-how mastered by the project's industrial partners, - The multidisciplinarity of the leading laboratory, particularly in energy systems, but also in nonlinear and hybrid dynamic systems in the context of spatial (porous materials, heterogeneity) and temporal (event and probabilistic) discontinuities. Optimization concerns the composition of energetic materials, as well as the induced industrial systems, at the level of ignition or combustion but also at small scale at the level of the organization of the heterogeneities. Indeed, the reactive medium leading to combustion or explosion must be perfectly defined from a physic-chemical point of view. For example, in the case of energetic materials such as pyrotechnic compositions, the grains stacking mode, in addition to the knowledge of their sizes and shapes, plays an important role at local level. In the case of low-vulnerability propellants, the energies and environmental conditions (pressure, nature of the pressurizing gases) must be well defined to obtain a safe and reproducible ignition despite the loss of sensitivity of the propellant. In addition to optimization, there is also a need to adapt to the new environmental conditions more and more present (e.g. REACH Regulation). This adaptability induces a continuous possibility of anticipation. This implies a better control of sensitivities of energetic materials and their relationships with the induced energy conversion system. To minimize the number of trials and errors, we propose, in this project, a multidisciplinary method to "capture" the relevant parameters, best translators of "local" to "global" and vice versa. It is based on a fine description, at temporal and spatial scales, of physic-chemical properties with the help of cellular automata model, inverse methods for parametric identification and images processing. It will then be possible to follow a flame front instantaneously, but also to define the pyrotechnic composition under anticipated constraints more and more severe. New materials are currently being developed for the replacement of pyrotechnic compositions in thermal batteries (consequence of the application of REACH Regulation). Combustion process of these substances may be affected, or even totally changed, in case of a partial or complete containment. We will therefore be interested in the evacuation of the propellant combustion products (gun propellant in interior ballistic applications) through a non-adiabatic tortuous channel with the search of a flow optimum in order to preserve the limit pressure necessary to maintain the quasi-stationary combustion. We will also optimize the transition of the combustion in a pyrotechnic environment modelled in 1D: transition from a first medium to a second one, through a discontinuity interface of the substance.