Spherical Numerical Simulation Of The Closed Container Of Flammable Gas Explosion

The investigation into explosion process of flammable gases, which can cause great economic loss and casualty, can provide references for making further study of explosion protection.In several research techniques, experimental investigation can not provide universal law for the restriction of experimental field, test method and funds. Analytic solution can also hardly offer its regulation of development. However, with the fast development of computer, numerical calculation became one of important methods of investigating flammable gas explosions.Main work of this paper can be sum up as follows:(1)At the base of hydrodynamics and chemical reaction kinetics, governing equations of describing explosion process of flammable gases are deduced simplified reasonably. Bakke-Hjergater combustion model is used in energy equation. A modified "simple" algorithm is adopted in procedure to solve pressure-velocity coupled problems. In discrete equations, implicit scheme is used for time item, and fist-order upwind difference scheme and central difference scheme are respectively used for convection item and diffusion item. The compiled procedure can simulate flammable gas explosion process in closed vessels effectively.(2) Based on the investigation into flammable gas explosions, explosion process of gas cloud in spherical closed vessels is simulated by modifying initial condition and boundary condition.(3) GUI (graphical user interface) is designed with MATLAB language to build design system of numerical simulation, which providing sub-modules of physical property parameters of various flammable gases. User can invoke this system at any moment or add other kinds of flammable gases to simulate their explosion process. Flammable gases (or gas cloud) explosion process of different kinds with different initial conditions can be simulated conveniently, the only work user should do is inputting design parameters according to interface presentation.Several conclusions can be drawn from computed results as follows:(1) For explosion process of flammable gases in closed vessels, flow field parameters, such as pressure, velocity, density, temperature, concentration and so on, vary with time and space. Numerical results show that, the maximum explosion pressure is proportional to initial pressure; the higher fuel activation is, the greater ascent rate of pressure and destructive power are.(2) For closed vessels with spherical shape, the bigger volume of vessel is, the smaller ascent rate of pressure becomes, and the volume of vessel has no effect on the maximum explosion pressure. As volume of vessel is smaller than 60 cubic meters, the maximum ascent rate of pressure and volume are approximately in accordance with cube law, and KGcomes near to a constant. For big volume vessels, the difference of KG is less than 10% compared with small vessels. As a whole, KG increases with the increasing vessel.(3) For explosion process of gas cloud in closed vessels, flow field parameters, such as pressure, velocity, density, temperature, concentration and so on, vary with time and space. Results show that, the maximum explosion pressure is proportional to initial pressure; for the same volume vessels, the power of flammable gas explosion is far greater than gas cloud. The bigger gas cloud radius is, the greater the maximum explosion pressure becomes.(4) By comparing numerical results with experimental data in literatures, it is found the maximum divagation is within 10%. Therefore, the built mathematical model can be used to simulate explosion development of flammable gases or gas clouds in spherical closed vessels.