AIR FORCE OFFICE OF SCIENTIFIC RESEARCHARLINGTON VA
Evolution of the ignition phase blast field of a tube or silo launched rocket is described in terms of three distinct phases or steps. The first or precursor phase is associated with leakage of the high pressure gas termed the launch gas used to eject the rocket from the tube. The second phase occurs when the bulk of the launch gas is released as the rocket base clears the end of the tube. Both these steps are analogous to their counterparts in the muzzle blast of a conventional gun. However, the third, and probably most severe, phase in the subject problem accompanies ignition of the rocket motor and initial production of thrust. The present report describes work performed on two facets of the subject problem. The first is analysis of the internal gas flow during start of the launch. Particular attention is given to formation of the salient characteristics of the flow field which will affect the precursor phase of the blast field. Results of several numerical examples are presented to illustrate the properties of the internal flow field. The second facet of the problem which has been studied is the ignition-phase blast field, per se.