Comparability of estimates of the impact of gunpowder and gas-dynamic explosions on the stability of buildings and structures

A brief description of natural and artificial influences influencing the stability of buildings and structures is presented. Studying the seismic resistance of buildings and structures designed, under construction, erected, and in operation requires time to wait for seismic activity, which is not permissible; costs of manpower and resources, which is inappropriate. In this regard, a working hypothesis has been put forward that by artificially acting on soils with the help of detonation wave energy, it will be possible to induce vibrations, with the help of which it will be possible to study the behavior of building structures put into operation, the entire building and structure as a whole. The goal is set: - to investigate the behavior of structures under construction and in the operation of buildings and structures that perceive artificial vibrations caused by the detonation unit by acting on soils. To achieve this goal, tasks have been identified. A detonation (blast) wave is taken as a "tool" for force action. The theoretical foundations of the experiment are briefly presented and the developed scheme of a detonation tube and a shock wave with a general view of the installation causing detonation wave energy. A brief technique for carrying out field experiments is presented.

DETONABILITY OF FUEL-AIR MIXTURES IN TERMS OF DEFLAGRATION-TO-DETONATION TRANSITION

A new experimental method for evaluating the detonability of fuel-air mixtures (FAMs) based on measuring the deflagration-to-detonation (DDT) run-up distance and/or time in a standard pulse detonation tube is used to rank gaseous premixed and nonpremixed FAMs by their detonability under substantially identical thermodynamic and gasdynamic conditions. In the experiments, FAMs based on hydrogen, acetylene, ethylene, propylene, propane-butane, n-pentane, and natural gas of various compositions, as well as FAMs based on the gaseous pyrolysis products of polyethylene (PE) and polypropylene (PP) are used: from extremely fuel-lean to extremely fuel-rich at normal temperatures and pressures.

Study on Effect of Obstacle Shapes on Filling Process in Pulse Detonation Rocket Engine

In order to explore the influence of obstacle shapes on the filling process of pulse detonation rocket engine under valveless self-adaptive working mode, the numerical simulations of two-phase single filling process and multi-cycle experiment were carried out, in which gasoline was utilized as fuel, and oxygen-enriched air as oxidizer. The effects of four kinds of obstacles with different shapes on the filling process of PDRE were studied. The results showed that the existence of obstacles blocks the filling of fuel into the tail of detonation tube, resulting in a great non-uniformity of filling results in the axial and radial directions. Fuel droplets collect near the head and wall of detonation tube, and droplets are seriously blocked by orifice plates. The detonation initiation and stable propagation can be achieved by Shchelkin spirals, annular grooves and spiraling grooves, while the detonation initiation cannot be achieved by orifice plates.

INITIALIZATION OF SUPERSONIC COMBUSTION BY INJECTING THE TRANSVERSE DETONATION WAVE INTO THE FLOW

The work presents the investigation results of the influence on supersonic oxygen- hydrogen mixture flow by the injected flow into it generated by a detonation tube installed in the supersonic channel wall. The goal of this work is to study the processes of chemical reaction initiation and flow reconstruction under such influence. The mathematical model of the combustion initiation in the experimental setup is developed within a continuous medium on the model-based of a chemically nonequilibrium single-temperature gas. For the combustion reaction of the oxygen-hydrogen mixture, the following main reagents were selected: H2O, OH, O, H, H2, O2, HO2, H2O2 and O3. The combustion kinetic scheme involving these reagents contains 27 reactions. The numerical solution of the equation initial system was found using a third-order noncentral difference scheme. The parameters of the flow initiating combustion were determined from the system of one-dimensional conservation laws for a detonation wave in a detonation tube.