A. A. Vasil'ev

Gas Detonation and its Application in Engineering and Technologies (Review)

The most relevant aspects of advanced experimental investigations of gas detonation and its mathematical simulation are presented. Examples of the engineering use of gas detonation are given.

Experimental Investigation and Numerical Simulation of an Expanding Multifront Detonation Wave

Results of experimental investigations of an expanding multifront detonation wave are presented. Two stages of spontaneous formation of new disturbances and transverse waves on the expanding detonation‐wave front are observed. The main mechanisms of re‐initiation of detonation waves are discussed. Two‐dimensional numerical simulation of the dynamics of a multifront detonation wave in a linearly expanding channel is performed. The effect of spontaneous formation of new disturbances and new transverse waves is confirmed by computations, and the main mechanism of multiplication of transverse waves is the instability of detonation‐wave‐front elements at the stage they cease to be in the overdriven state and are attenuated during expansion.

Critical energy of initiation of a multifront detonation

ConclusionsOn the basis of the theoretical cell model and the experimental data on the emergence of the detonation from narrow channels into a half-space, we have constructed a model of the “direct” initiation of the detonation. The formulas obtained enable us to estimate the critical initiation energy practically for any experimental conditions. As the initial data, in the formulas we use only the density of the mixture, the velocity and dimension of a cell of the self-sustaining detonation, and also the time and space characteristics of the energy generation.The use of the model is based on a relatively simple experimental determination of the cell dimension for the mixture being investigated. In other models available today, for example [1–7], kinetic data on ignition delays are used; the inaccuracy in determining these may lead to considerable errors in the calculation of the initiation energy. A verification of the proposed model on the basis of existing experimental results is difficult because there are not enough data given in the published studies. Depending on the completeness of the information we have shown the quantitative or qualitative agreement between model and experiment.

Initiation of a Porous Explosive by Overdriven Gas Detonation Products

This paper reports results of experiments on initiation and development of detonation in cylindrical charges of a porous explosive by overdriven detonation products of a gas mixture C2H2 + 2.5 O2. Explosive charges with a bulk density of about 1 g/cm3 in fragile shells were studied. For PETN and RDX charges, the critical initial pressure of the gas mixture at which detonation initiation still occurs is determined and the pressures acting immediately on the charge are given. For PETN, critical initial pressures and initiation delays were measured for the first time for charges with particles of various diameters. The obtained dependence characterizes the following abnormal property of porous charges: there is an optimum particle size for which the explosive sensitivity is maximal. Streak records of self‐luminosity for typical initiation modes are given. Mass velocity profiles in initiation waves at different depth of the charge are obtained using an electromagnetic procedure.

Estimation of the Combustion and Detonation Parameters for Hydrocarbon Gas Hydrates

Calculated combustion and detonation parameters for methane—oxygen (air)—H2O and acetylene—oxygen (air)—H2O mixtures are presented. The values of the critical detonation–initiation energy are estimated as applied to methane and acetylene hydrates.

Characteristic regimes of multifront-detonation propagation along a convex surface

Experimental results of multifront-detonation diffraction on a convex curvilinear surface are given. An estimate of the minimum gas-layer thickness, which is necessary for the external circumferential rotation of a multifront wave, is proposed. The characteristic propagation regimes are established in annular channels: complete destruction of detonation and combustion, high-speed combustion, galloping detonation, and multifront detonation.