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An improved reactive flow model with thermodynamic consistency is proposed to deal with the detonation hydrodynamics of solid explosives. Based on the assumption that the chemical mixture composed of solid-phase reactants and gas-phase products can arrive at mechanical equilibrium, but cannot arrive at thermal equilibrium, the solid-phase reactants and gas-phase products may possess one pressure and one velocity, but two temperatures or internal energies. With the help of the energy conservation of the mixture and pressure equivalence between the constituents, the conservation equation of internal energy and the evolution equations of the volume fraction for the solid-phase reactants and of pressure for the chemical mixture are derived. Thus, the full governing equations of the proposed detonation model include the conservation equations of mass, momentum, and total energy, and the evolution equation of pressure for the chemical mixture, and the conservation equations of mass and internal energy, and the evolution equation of the volume fraction for the solid-phase reactants. The theoretical analysis shows that there exists a distinct discrepancy between the proposed model and the Zel'dovich–Neumann–Döring detonation model for the steady structure of the detonation wave. The numerical simulation results of typical detonation problems show that the important characteristics of detonation flows can be well captured and also demonstrate that the proposed detonation model of solid explosives is reasonable. [ABSTRACT FROM AUTHOR]

Abstract Experimental and numerical investigation of hydrogen-air and hydrogen-oxygen detonation parameters was performed. A new detonation model was introduced and validated against the experimental data. Experimental set-up consisted of 9 m long tube with 0.17 m in diameter, where pressure was measured with piezoelectric transducers located along the channel. Numerical simulations were performed within OpenFoam code based on progress variable equation where the detonative source term accounts for autoignition effects. Autoignition delay times were computed at a simulation run-time with the use of a multivariate regression model, where independent variables were: pressure, temperature and fuel concentration. The dependent variable was the autoignition delay time. Range of the analyzed gaseous mixture composition varied between 20% and 50% of hydrogen-air and 50%–66% of hydrogen in oxygen. Simulations were performed using LES one-equation eddy viscosity turbulence model in 2D and 3D. Calculations were validated against experimental data. Highlights • Experimental study of hydrogen-air and hydrogen-oxygen detonation is presented. • Distributions of the measured detonation cell sizes are depicted. • A new autoignition model of detonation based on the multiple regression is proposed. • 2D and 3D numerical simulation results are validated against the experiments. [ABSTRACT FROM AUTHOR]

The combustion of nanometric aluminum (Al) powder with an oxidiser such as molybdenum trioxide (MoO3) is studied analytically. This study focuses on detonation wave models and a Chapman-Jouget detonation model provides reasonable agreement with experimentally-observed wave speeds provided that multiphase equilibrium sound speeds are applied at the downstream edge of the detonation wave. The results indicate that equilibrium sound speeds of multiphase mixtures can play a critical role in determining speeds of fast combustion waves in nanoscale Al-MoO3powder mixtures. [ABSTRACT FROM PUBLISHER]

Abstract: In order to ensure the public acceptance of the newly introduced technologies, such as e.g., exponentially growing hydrogen utilization, the risk management of them must be brought at the corresponding height. As a part of modern risk assessment procedure, CFD modeling of the accident scenario development must provide reliable data on the possible pressure loads resulting from explosion processes. The expected combustion regimes can be ranged from slow flames to deflagration-to-detonation transition and even to detonation. In the last case, the importance of the reliability of the simulation is particularly high since detonation is usually considered as a worst case scenario. A set of large-scale detonation experiments performed in Kurchatov Institute on RUT facility was selected as a benchmark. Due to the fact that RUT facility has typical industry-relevant characteristic dimensions, the capabilities of several CFD codes to correctly describe detonation in such scales for different hydrogen–air mixtures were surveyed. Two detonation tests were selected with uniform hydrogen–air mixtures and concentrations of 20.0% and 25.5% vol. Three CFD codes with different detonation models were used to simulate those experiments. A thorough inter-comparison between the models and the simulated process characteristics was performed. The obtained results allow improving the predictive capabilities of detonation models, providing a basis for the models validation and for future code development. [Copyright &y& Elsevier]

A two‐phase detonation model of solid porous explosives, which takes into account the compression of solid‐state particles and the presence of a solid component in detonation products, is developed. The homogeneous detonation mechanism based on the Arrhenius‐type reaction is studied. Detonation is initiated by the region of high‐pressure and high‐temperature gases modeling the detonator explosion. A numerical experiment confirms that there exists an initiation‐pressure limit below which no homogeneous mechanism of detonation is active. The detonation wave has the leading front in which the explosive is precompacted and the gas in the porous volume is compressed up to a pressure of ≳ 100 GPa without any significant change in particle density. Then the gas compresses the particles themselves up to the pressure and temperature of the thermal explosion. As a result, the leading front is followed (after a certain delay) by a narrow reaction zone where detonation products are formed with a further increase in pressure. [ABSTRACT FROM AUTHOR]