Ignition and Combustion of Composite Solid Propellants Based on a Double Oxidizer and Boron-Based Additives
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USTION, EXPLOSION, AND SHOCK WAVES
Ignition and Combustion of Composite Solid Propellants Based on a Double Oxidizer and Boron-Based Additives A. G. Korotkikha, b, *, I. V. Sorokina, E. A. Selikhovaa, and V. A. Arkhipovb aNational
Research Tomsk Polytechnic University, Tomsk, 634050 Russia Research Tomsk State University, Tomsk, 634050 Russia *e-mail: [email protected]
bNational
Received August 28, 2019; revised January 29, 2020; accepted February 20, 2020
Abstract—The use of boron-based powder materials in solid propellant compositions is an effective method for increasing the energy characteristics in the combustion chamber due to increasing the released energy through the combustion of boron particles. In this study, powders of amorphous boron and aluminum borides, obtained by the method of self-propagating high-temperature synthesis—the SHS method, which were added to the composite solid propellant composition based on a double oxidizer and an energy fuel binder, are studied. The paper presents the characteristics of thermal decomposition, ignition, and combustion for solid propellant samples. The tested samples are ignited using a continuous CO2 laser in the air in the heat flux density range of 90 to 200 W/cm2. The combustion of propellant samples is carried out in a manometric bomb in a nitrogen atmosphere at pressures ranging from 0.5 to 7.0 MPa. It is shown that the use of amorphous boron and aluminum boride powders in the solid propellant composition reduce the ignition delay time and increase the burning rate of the samples compared to the aluminum-based propellant composition, due to the increase in temperature near the surface of the reaction layer of the sample and the specific heat release during the oxidation and burning of boron. Keywords: composite solid propellant, ammonium perchlorate, ammonium nitrate, aluminum, boron, aluminum boride, ignition delay time, burning rate DOI: 10.1134/S1990793120040089
INTRODUCTION Boron and metal boride powders are the most promising components of solid and hybrid propellant due to their high specific energy released during oxidation and combustion. Among the metal combustible solid propellants, used in the aerospace industry, boron has the highest values of mass and volumetric heat of combustion, ~58 kJ/g and 136 kJ/cm3, respectively [1–4], which is about twice as high as that of aluminum. In this case, boron particles have long ignition and combustion times due to the formation of an inert oxide layer on the particle surface, which ultimately leads to the incomplete burning-out of particles when they are moving in the combustion chamber. The melting and boiling points of boron oxide are 450 and 1860°C [2], respectively, which is significantly lower than for pure boron (2075 and 3658°C [1]). The boron combustion process is multistage with substantial consumption of the oxidizer and includes heterogeneous reactions between the gaseous oxidizer, the liquid phase of boron oxide, and the solid phase of boron [5– 7]. In modern rocket engines, the air flow velocity
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