Search Results

Computations are reported of transient axisymmetric pulsating and evaporating sprays that account also for drop collisions and coalescence. It is found that, for the same upstream and gas conditions, pulsating injections result in smaller drops than continuous injections. The difference is particularly marked at high gas densities and is due to the inhibition of collisions and coalesce of drops generated by the gas gap in between the pulses. However, the tip penetration rates are not markedly different for continuous and pulsating injections. For transient evaporating sprays it is found that all drops except the largest evaporate within a well defined distance from the injector. Beyond this distance only vaporized liquid and entrained gas continue the penetration. For engine applications the length of the liquid core is found to be of the order of centimeters and sensitive to conditions. In particular it decreases with increasing injection pressure, gas temperature, and gas density.