The injection of a water spray within an enclosure prone to explosion is reputed to reduce the risk. This strategy for safety improvement is at the root of numerous experiments that have concluded that premixed flames can be extinguished by a sufficient amount of a water aerosol characterized by suitable droplet sizes. On the other hand, certain experiments seemingly indicate that flame speed promotion can be observed when particular water mists are injected within the premixture. To contribute to shed light upon these less than intuitive observations, we propose to study the propagation of a nearly stoichiometric premixed flame within a 2D-lattice of water droplets. Main parameters of investigation are droplet size and droplet inter-distance (or equivalently, the lattice spacing). When the droplet interdistance is small, the results confirm that a sufficient amount of water quenches 20 combustion. For larger droplet interdistance, we observe a flame speed enhancement for suitable droplet size. Concomitantly, the flame front folds subjected to Darrieus-Landau instability. A previous approach with Sivashinsky-type model equation for DL instability is finally in- voked to interpret such a flame speed promotion in presence of water aerosol.