Experimental Investigation of Acoustic Resonance in Solid-Propellant Combustion

Abstract

Oscillatory burning is a complicated phenomenon. The most fruitful and stimulating contribution to its understanding has been the acoustic theory of F. T. McClure, R. W. Hart, and their associates. The most important single concept of the theory is the recognition of the acoustic admittance as the key property of the combustion process. Of the several streams of research aimed at determining the acoustic admittance of burning surfaces, the most productive has been that employing the device known as the side-vented endburner. Work with this tool is proceeding in at least seven laboratories, the three that have been in the business longest being at the University of Utah (UU), at the Naval Ordnance Test Station (NOTS), and at the Ballistics Research Laboratory (BRL). This paper summarizes related aspects of the work at these three laboratories. Despite variations in burner design, experimental procedures, kinds of data, and data-processing methods, the three laboratories report acoustic admittances in good agreement. In addition to their common work, the three laboratories have branched into other aspects of the oscillatory-burning problem. Some of these aspects are investigation of burner characteristics (BRL), the quantitative influence of oscillatory-burning suppressants (NOTS), and the participation of the solid phase in acoustic oscillations (UU).