Scaling of Rocket Nozzle Admittances

Abstract

To apply the admittance data measured experimentally for small-scale nozzles, the necessary scaling criteria must be established. The results of an investigation undertaken to determine these criteria are presented and the data indicate that under cold-flow conditions the damping of axial instabilities provided by full-scale nozzles can be determined from the attenuation data obtained experimentally for geometrically similar small-scale nozzles. The scaling of both short and long nozzles has been investigated. The experimental data also support the scaling criteria proposed by Crocco in his analytical investigation of nozzle damping.