Combustion behavior of electrically controlled solid propellant with tungsten additive

Abstract

In recent times, there is a growing interest in utilizing the controllable solid propellant combustion that facilitates multiple start and stop bits of the electrically controlled solid propellant (ECSP) combustion at will. This paper is an attempt to understand the effect of tungsten metal additive in the ECSP. The tungsten metal powder (1 μm size) is blended with the lithium perchlorate (LP) and polyvinyl alcohol (PVA) along with other ingredients. LP and PVA form the baseline composition, and metal content is added between 5 and 15% by weight. Thermal analysis of the ECSP samples were conducted at 5 °C/min utilizing differential scanning calorimetry (DSC) and thermogravimetry (TGA) in the temperature range of 30 °C–600 °C, and the results showed that the dominant exothermic peaks occur around 260 °C. High speed imaging facilitates in understanding the combustion characteristics of the ECSP samples. The ignition is achieved by applying 300 V DC supply across the molybdenum electrodes. ECSP combustion can be divided into two distinct phases of burning that can be designated as the transient burning and the steady phase burning. It is found that the burning rate was 38.2% faster for 15%-metalized ECSP than 5%-metalized. In addition, multi-wavelength pyrometry was used to obtain the average flame temperature, and it was observed that the flame temperature was 9% lower for 15%-metalized than 5%-metalized. Hence, this study enunciates the burning characteristics of tungsten based ECSP and helps in realizing the potential use of tungsten as a metal additive in the ECSP for micro thrust generation.