Contemporary methods to measure regression rate of energetic materials: A review

Various energetic materials, including solid rocket propellants, have found numerous applications in aerospace technology in the past decades. This growing interest initiated an increasing number of experimental and technological studies, leading to a wide range of published experimental data. Due to the intrinsic challenges of data acquisition and processing, assessing the accuracy of the measurement results is important. In this paper, a review of existing experimental techniques for measuring the regression rate of energetic materials is presented along with a description of the fundamental physical principles used for developing the particular methods. Special attention is paid to recent developments in measurements of highly-dynamic processes. Technical requirements for correct determination of regression rate are analyzed focusing on the methods associated with transient combustion. Emphasis is placed on laboratory-scale methods intended to obtain correct and reliable data on regression rate in well-characterized environments that can be used for comparison with theoretical predictions. The measurement methods are divided into direct and indirect ones. It is shown that direct high-speed photography could not be effectively used for recording regression rate oscillations with frequencies higher than 30–50 Hz. The same limitation applies to classical ultrasound techniques and X-ray radiography. However, radiography techniques based on synchrotron and terahertz radiation are promising. Special attention is paid to development of microwave and laser recoil methods that provide high spatial and temporal resolution capable of correctly determining transient regression rate.