Optimum geometries for scarfed perfect nozzles

The results of an investigation to determine the optimum geometry for length constrained scarfed nozzles employing perfect expansion contours is presented. A scarfed perfect nozzle performance analysis, based on an axisymmetric flowfield model and utilizing the method of characteristics solution technique, was developed. The performance model was utilized in an optimization procedure to determine, for a range of nozzle projected lengths, the optimum set of scarfed perfect nozzle geometries. For each projected length, the respective optimum nozzle geometry was selected to maximize motor axial thrust coefficient. The set of optimum scarfed nozzle geometries was compared against optimum length constrained scarfed nozzles employing conical expansion contours. The optimum scarfed perfect nozzle geometries generated by this investigation were specifically produced for utilization in a design methodology developed to minimize the length of tactical solid propellant propulsion systems. Used in conjunction with the design methodology, the results of the present investigation provide the designer with a means of further reducing propulsion system length. (Author)