Restitution methodology for space and time dependent solid-fuel port diameter evolution in hybrid rocket engines

Abstract

A post-processing tool for experimental data is developed to rebuild the instantaneous and local distributions of the fuel port diameter and the fuel regression rate throughout the port conduct during a firing test. The main objective is to use the developed methodology to be able, at a given instant during the firing test, to simulate a hybrid rocket engine configuration and to validate the related numerical modeling. The methodology is based on the coupling between the instantaneous fuel mass flow rate obtained by a ballistic reconstruction technique and the port diameter measurement throughout the port conduct after the firing test. The ballistic reconstruction method is adapted and applied to an experimental hybrid rocket, using hydrogen peroxide/high density polyethlylene propellants, with a catalytic injector (HYCAT). Firstly, a set of representative firing tests is selected from the HYCAT hybrid rocket engine testing campaign. Secondly, an analytical approach leads to instantaneous evolutions of the fuel port diameter and the fuel regression rate profiles throughout the fuel port conduct. The rebuilt profiles of the instantaneous port diameter show the ability of the methodology to restore the space and time distribution of the fuel port diameter. Nevertheless, the fuel regression rate distributions show some limitations of the methodology even though the average is coherent with the ballistic reconstruction trends.