Penetration Distance of Retrorocket Exhaust Plumes into an Oncoming Stream

摘要

A simple method for predicting the penetration distance of highly underexpanded retrorocket exhaust plumes into an oncoming free stream is developed and compared with experimental data. It is shown that the measured jet penetration distance and the standoff distance of the free stream bow shock wave are predicted closely by computing the plume flow field, using the method of characteristics for an axisymmetric plume exhausting into still air at a pressure equal to the oncoming free stream static pressure. The method is applied to a single jet and to a cluster of n identical jets. For the latter, the cluster is considered to be an equivalent single retrorocket having the same mass-flow rate (and thus an equivalent diameter (n) l/2 times as large as the nozzle exit diameter of a single rocket). (Author)