Explosion of dust suspensions coming from plant biomass (starch cellulose and lignocellulosic particles) has been studies in closed vessel for propulsion applications. Performances likely to be obtained with these particles have been estimated by means of a thermomechanical code. Theoretical constant volume combustion pressures of cellulose/air mixtures are higher than those of usual hydrocarbon/air mixtures. Experiments were conducted in a 20-l cylindrical chamber with an aspect ratio L/D = 2.2. The measured maximum explosion pressures are 30% lower than the theoretical pressures. They are dependent on particle nature and concentration and on the initial state of the suspension. A significant proportion of unburnt particles was found in the chamber after the combustion of rich dust/air mixtures. The process of suspension generation was specifically studied for three devices: first, experimentally, by optical diagnosis (PIV, and fast laser tomography) and then, by computer simulations. In order to improve performances, some experiments have been carried out with "hybrid" mixtures (cellulose particles/methane/air). They showed that for the same global equivalence ratio the explosion pressures in hybrid mixtures are higher than in methane/air or particles/air mixtures taken separately and, the amount of unburnt products is strongly reduced. Moreover very lean methane/air mixtures can be ignited when added to a dust suspension of adequate concentration.
