Method for Determining Nozzle-Throat-Erosion History in Hybrid Rockets

Abstract

The authors of this paper introduce a new reconstruction technique titled nozzle-throat reconstruction technique to estimate nozzle-throat-erosion history and oxidizer-to-fuel-mass-ratio history in hybrid rockets. Nine static-firing tests were carried out on a 2kN-class cascaded multistage impinging-jet-type hybrid-rocket motor under varying oxidizer-flow rates to evaluate the accuracy of reconstructed results. Nozzle-throat-erosion histories calculated by the nozzle-throat reconstruction technique agreed well with measured values for initial nozzle-throat radius, and successfully reconstructed the case, in which no measurable amount of nozzle-throat erosion occurred. For equivalence ratios 0.6–1.4, the relationship between nozzle-throat-erosion rate and equivalence ratio of reconstructed results displays a trend consistent with chemical-kinetic-limited heterogeneous-combustion theory, as well as predictions made by previous researchers.