Effects of Temperature Conditioned Environment on a Propellant's Pressure-Coupled Response

Abstract

The purpose of this work is to evaluate and understand initial temperature effects on the pressure-coupled response function of solid propellants. This paper will cover experiments performed with the T-burner at China Lake. The T-burner is the current standard method of measuring a propellant’s pressure-coupled response. Pressure-coupled response is the ratio of oscillating burning rate over the mean burning rates to the oscillatory pressure over the mean pressure. A relationship between temperature sensitivity and pressure-coupled response has long been assumed based on the theoretical derivation of the pressure-coupled response function and also some limited anecdotal evidence. Unfortunately, this relationship has only limited data to support this assumption and very little has been published on this topic. This study performs a comprehensive examination of these effects on one particular propellant over a broad frequency spectrum at a typical pressure in the T-burner. In this experiment, propellant samples, along with the whole T-burner chamber, were temperature conditioned to a set temperature prior to testing. Four temperatures were used in this experiment:, ambient (roughly 300K or 80°F), 344K (160°F), 355K (180°F), and finally 222K (-60°F). Once the chamber and propellant samples reached thermal equilibrium, response testing was then performed. Testing revealed that at both temperature extremes this propellant’s pressure-coupled response was increased. This increase was largest at higher frequencies leading to increased likelihood of tangential modes and additional nonlinear behavior. Temperature sensitivity was also determined from the T-Burner data and compared to that from small-scale motor firing data.