Detonation of heterogeneous media composed of liquid fuel sprays in air has been investigated in a square cross section (53x53mm), 4-meter long detonation tube. Particular attention was paid to the influence of the droplet size on the conditions of existence of the detonation, its characteristics of propagation and the existence of a cellular structure similar to that observed in homogeneous gaseous mixtures. With volatile fuels (Heptane, Isooctane), the cellular detonation structure was displayed for droplets of diameter d0=8 μm. On the other hand, for 30- or 45-μm droplets, either a spinning detonation or a limit detonation mode, with large and irregular cells, can be observed. In less volatile fuels (Octane), detonations were observed only with 8- and 30-μm droplets, whereas with d0=45-m droplets, the detonation cannot be established whatever the equivalence ratio. With low volatile fuels (Decane or Dodecane), it is not possible to initiate a detonation for d0=30 or 45 μm. The detonation was obtained only for d0=8 μm droplets, with the cellular structure in the case of decane, and the spinning regime with dodecane. A numerical model was developed to simulate the detonations in heterogeneous mixtures gas / droplets. For d0=30μm and d0=45μm, mechanical disintegration of the droplets under the effect of the shock must be taken into account to obtain a detonation. For d0=8μm, the disintegration is not necessary. The results concerning the influence of the droplet size on the dimensions of the cellular detonation structure are in reasonable agreement with the experiments.
