Efflect of high-voltage pulsed discharges on deflagration to detonation transition

An experimental study of ignition and detonation initiation by two different kinds of high-voltage pulsed gas discharge has been performed in two smooth detonation tubes. The experiments were carried out at pressures ranging from 0.15 to 1 bar in various gaseous stoichiometric mixtures. In the first setup, a distributed nonequilibrium nanosecond discharge was used for mixture excitation and ignition. In the second setup, a localized microsecond pulsed spark discharge with a stored energy of 14 J developed. The electrical parameters of the discharges, ignition delay time, flame front, and shock wave velocities were measured in the experiments. Essentially, higher efficiency of the nanosecond discharge as a detonation initiator has been demonstrated: deflagration to detonation transition was observed 3 tube diameters away from the discharge chamber in different C3H8/C4H10 + 5O(2) + xN(2) and 0.5C(6)H(14) + 4.5O(2) + xN(2) mixtures with N-2 concentrations up to 38 %. The energy input in these cases did not exceed 3 J, and the deflagration to detonation transition time was less than 1 ms. The microsecond spark discharge ignited the mixture efficiently, but the transition length and time increased significantly.