Chemical aspects in shock ignition of fuel drops

Effects of nitrates on hydrocarbon-air flames and detonations

“…15). A similar Arrhenius behavior was reported by Lu et al (1972Lu et al ( , 1974Lu et al ( , 1977 for heptane and kerosene in air sensitized by n-propyl nitrate (NPN). Note that heptane has a higher vapour pressure than NPN, whereas kerosene has a lower vapour pressure (Tables 1 and 2) pressure might be less significant than the chemical effects induced by the nitrate.…”

“…It is known that the detonation of a spray is predominantly controlled by three time scales: the droplet breakup time, the vapourization time and the chemical reaction time of the vapour. For a spray with large fuel droplets (∼ 10 2 -10 3 µm) and low vapour pressure, such as decane and kerosene, the "quasi-detonation" process is dominated by the droplet breakup mechanism (Dabora et al 1968(Dabora et al , 1969(Dabora et al , 1972Borisov et al 1970;Lu and Slagg 1972;Bar-Or et al 1981). The general sequence of the break-up mechanism is: 1) formation of a fuel micro-mist in the droplet wake by the breakup of fuel droplets via boundary layer stripping and Taylor instability; 2) ignition and explosion of the micro-mist that generate a blast wave, which ignites the rest of the droplet and supports the propagation of the leading shock front.…”

“…To promote the ignition of a spray detonation wave with large fuel droplets or low vapour pressures, additives such as nitrates have been used to sensitize hydrocarbon liquid fuels (Lu and Slagg 1972, 1974, 1977Lin et al 1984;Dabora 1980;Borisov et al 1983aBorisov et al , 1983b. The literature on the detonability of some hydrocarbon fuels sensitized by n-propyl nitrate, CH 3 (CH 2 ) 2 NO 3 , is summarized in Table 1.…”