Study on the effects of initial pressure and temperature on the explosion characteristics of DME-blended LPG mixtures in an obstructed confined pipeline

Numerical analyses were conducted to study the explosion characteristics of premixed LPG/DME/Air mixture in an obstructed confined pipeline of length 3 m and diameter 0.1 m under a wide range of initial pressures (100 to 300 kPa) and temperatures (−20 to 200 °C). The explosion overpressure, flame temperature and flame propagation along axial direction were investigated. The results indicated that the maximum explosion overpressure was raised significantly with increasing initial pressure, while decreased with the increase of initial temperature. Under lower initial pressure (P₀ ≤ 150 kPa), there was an obvious increase in the peak flame temperature as the initial pressure increased. However, when the initial pressure exceeded 150 kPa, the effect of the initial pressure on the peak flame temperature was not significant. At the same time, however, the peak flame temperature increased almost linearly with the increase of initial temperature. The structure of flame front experienced a change of “spherical flame - finger flame - tulip flame” at all conditions. The change of flame velocity was also divided into three stages in the study, namely rapid growth, gradual decline, backward propagation. In the “rapid growth” stage, both the velocity and the acceleration of the flame increased with initial pressure and temperature rising, but the influence of the initial pressure on the flame velocity became weak when the initial pressure exceeded 200 kPa.