Sprays detonations

J.A. Nicholls, Drop-Size Effects in Spray Detonation , 12th Symp Combstn (1969)... 

E. K. Dabora, Fundamental Mechanisms of Liquid Spray Detonations, in Fuel-Air Explosions, J. H. S. Lee and C. M. Guirao, eds., Waterloo, Canada University of Waterloo Press, 1982, 245-264. 

INVESTIGATION OF SPRAY DETONATION CHARACTERISTICS USING A CONTROLLED, HOMOGENEOUSLY SEEDED, TWO-PHASE MIXTURE... 

Spray detonation is a difficult phenomenon to study. One cannot easily create a two-phase mixture that is practical, well-controlled, well-characterized, and detonable. It is even less straightforward to create such a mixture on a scale large enough to allow a detonation propagating through the mixture to approach steady state. Past studies of spray detonation have exhibited only some of these features. They have typically utilized uniform arrays of impractically large droplets of fuel or uncontrolled clouds of fuel in which little beyond mean droplet size has been determined. 

To achieve a solid understanding of spray detonation phenomena, however, one must have the ability to control and characterize all of the pertinent system variables. These variables must be held constant over the length of the detonation s run. Only in this way can one perform a properly designed experiment in which the effect of each variable is investigated and analyzed independent of the others. 

Initiation of spray detonation is achieved using an incident gas-phase detonation wave. The top section of the detonation tube (which includes the top two-phase modules) is filled with a stoichiometric mixture of ethylene and oxygen immediately prior to firing the fuel injectors. The fuel injectors are then fired. After a predetermined delay period, a plasma jet in the top flange is fired, which... 

For experiments in which the equivalence ratio was greater than 0.2, it was found that the measured velocity was lower than that predicted by CJ calculations. This was not unexpected — previous studies have reported velocity deficits for spray detonation. It was found that the velocity deficit increased with equivalence ratio. Liquid mass loading also increases with equivalence ratio. It is therefore possible that this effect is due to gcis-phase saturation or to processes that tend to slow the evaporation rate of the droplets (e.g., cooling due to latent heat). It can be further noted that the velocity deficit increases with decreasing fuel pressure (i.e., with increasing droplet diameter). This may also be attributable to a decreased rate of evaporation. Velocity deficit and its causes will be explored in more detail in future experiments. 

A fundamental study at Stanford University by Edwards and his coworkers (Chapter 1) in examining the effect of a two-phase mixture state on spray detonation characteristics has been initiated preliminary results using hexane are presented. Santoro and his associates (Chapter 2) have performed a series... 

Ceramic or cermet thermal spray materials deposited by plasma spraying, detonation gun (D-gun), or high-velocity oxyfuel processes... 

Thermal spray processing A coating process where material (wire, rod, powder) is melted by a flame, plasma, electric arc, or some other means and the molten particles are propelled in a high velocity gas stream to the substrate surface, where they are splat cooled at a high quench rate. See also Arc-wire spray Detonation flame spraying Flame spray High velocity oxygen fuel (HVOF) spray Plasma spray. 

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