In order to investigate the effects of three different electrostatic discharge energies on gas explosions, a
high-speed PIV system has been applied. The present study paid attention to the flame initiation by the gas
explosions and its propagation at the existence of an obstacle within a chamber. Three different ignition
energies such as 0.56 mJ, 52.87 mJ and 112.5 mJ were used. It is found that the ignition kernel is bent by the
electrostatic discharge during the flame initiation. Tangential velocities of unburnt mixture ahead of initially
propagating flame fronts are increased with increasing ignition energy, which makes the flame propagation
faster before it reaches the obstacle. Although the flame speed was found to be less sensitive to the ignition
energies, the flame developments were different. The effects of the energies on explosion pressures were also
discussed.