Experiments are performed on a number of deflagration-to-detonation (DDT) enhancement techniques for use in a H2/Air pulsed-detonation engine (PDE). The mechanism, speed and location of DDT for three configurations are considered, including a Shehelkin spiral, an extended cavity/spiral and a co-annulus. High speed digital imaging is used to track flame propagation. and simultaneous time-correlated pressure traces are used to record progress of the shock structure. It is found that DDT is initiated primarily through local explosions that are highly dependent on the particular geometry. In addition to various geometries. The effect of equivalence ratio and spark timing are also investigated.