Mechanism of detonation formation as a result of free flame propagation in unconfined space

The problem of the detonation formation as a result of unconfined flame propagation is solved numerically. The mechanism of detonation formation is distinguished. It is related to the local formation of shock waves du- ring the linear stage of development of flame front perturbations formed on the surface of the expanding flame front. General criteria of the establishment of the conditions for the detonation transition via the proposed mechanism are formulated.