Parametric studies of electrohydrodynamic spraying.

Abstract

whole motor still could sustain detonation. Secondly, since the jet velocity appears to decrease with increasing core diameter, it takes longer for the jet to reduce the web thickness by the postulated high burning-rate process, because it is more closely followed by the reaction in the propellant. The pressure in the core should be dependent on the velocity of the jet, so that the propellant surface would burn more slowly under the conditions imposed by a slower jet. These considerations suggest less interference by jet formation in large-core motors. In summation, the conclusion regarding detonability of a hollow motor grain is that if it exceeds the predicted critical size, it should be expected to sustain detonation over the entire length of the motor. The contingencies on this assumption approach negligible importance as the hollow grain is scaled up from the small sizes that have been tested. In criticaldiameter studies, it was established that the critical diameter of unadulterated PBAN propellant, ANB-3226, is between 5 and 6 ft. This means that a large, hollow-core rocket motor of this propellant will be supercritical if its web exceeds 26-32 in. It is very important that one remembers that after detonability has been established, it is necessary to know under what conditions the grain can be initiated. The concern of Project SOPHY is to determine the initiation criterion as well as the sustainment criterion. Progress in this area has been reported.' The possibility that large motors cast with composite propellant can be detonable brings a high priority to increased investigation and comprehension of the initiation process.