Исследован взрыв газа в цилиндре диаметром 20 см и длиной 150 см, закрытом с обоих концов и имеющем отверстие на боковой поверхности; размеры и положение отверстия в опытах изменялись. Исследование проведено путем численного моделирования в рамках SFD-моделей с использованием метода крупных частиц - LPM (Large Particle Method) и программного продукта “Вулкан-М”. Показана адекватность математической и компьютерной моделей путем сравнения результатов численного и физического экспериментов, полученных в условиях, близких к рассмотренным. В результате моделирования уточнены известные данные по зависимости давления взрыва от расстояния между местом воспламенения и отверстием, и показано, что эта связь неоднозначна и зависит от размеров отверстия. Выявлены аномалии в виде колебаний с большой амплитудой в определенном диапазоне значений размера отверстия и при его различном положении. Обнаружен эффект, очень похожий на феномен “поющего пламени” Хиггинса. Показано, что колебания давления и площади фронта пламени приводят к повышению давления взрыва.
The aim of this work was to investigate the explosion of propane-air mixture in a cylindrical tube with 20 cm in diameter and 150 cm in length, closed at both ends and having hole on the lateral surface, dimensions and position of which were varied according to conditions of experiments. The study was conducted by numerical simulation within 3D CFD (Computational Fluid Dynamics) models based on a system of fundamental conservation equations applied to problems of gas dynamics, which supplemented by equations describing the propagation of a flame. System of approximating equations was solved by the large-particle method (LPM) developed by Belotserkovskiy O. M. and Davydov Yu. M. This method involves applying the rigid grid, placed in the calculated area and formed from about 90 thousands of the so-called “particles”, through which move the gas flows. Comparison of the results of numerical experiments and previously conducted physical experiments show the adequacy of the mathematical model. As a result of studies it was confirmed the known dependence between the explosion pressure and the diameter of a hole. Furthermore, it was shown that the dependence of explosion pressure on size and position of a hole on the lateral surface is ambiguous. Decrease of the distance between the hole of a smaller size and the source of ignition leads to rising explosion pressure (while increase of the distance leads to its lowering). The abnormal development of explosion in the form of self-oscillation with large amplitude in a certain range of size and position values of a hole was revealed during experiment. This effect is very similar to the “singing flame” phenomenon of Higgins. In conditions of pressure oscillations there were observed the fluctuations of position and size of the flame front. Oscillations lead to significant increase in pressure compared to explosions without oscillations. It should be noted that the possibility of appearance of the self-oscillation mode of explosion is known from the data of physical experiments, but such mode was modeled for the first time. It is known that previous attempt to create such mode using FLACS software was unsuccessful.
The authors declare that there are no conflicts of interest present.