Ammonium perchlorate-based composite solid propellant formulations with plateau burning rate trends

Abstract

This paper presents burning rates as a function of pressure of several propellant formulations based on ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene cured by isophorone diisocyanate, many of which exhibit significantly low (nearly zero or negative) values of the pressure exponent of the burning rate in distinct pressure ranges, termed as plateau burning rate trends. The propellants contain a bimodal distribution of AP particles with the size of the coarse and fine particles within narrow ranges whose mean values are widely separated. Two mean sizes of fine particles were considered for the propellant formulations in the present work, namely, 5 and 20 µm. These choices are based on the mid-pressure extinction behavior exhibited by the matrix of fine AP and binder contained in the propellants but when tested alone over a wide range of fine AP size and pressure. The propellants that include the fine AP/binder matrixes exhibiting a mid-pressure extinction, in turn, exhibit the plateau burning rate trends within the corresponding pressure ranges. A plateau is also observed at elevated pressures in the burning rates of some formulations, which is related to the diminishing relative importance of the near-surface leading-edge region of the oxidizer/fuel diffusion flame in the gas-phase combustion zone. The choice of the coarse AP size influences the exact pressure range within the mid-pressure extinction domain of the matrix where the propellant exhibits the plateau burning rate trends.Key words: composite solid propellants, plateau burning rate trends, mid-pressure extinction, bimodal distribution.It is well known [1] that a low value of the pressure exponent of the burning rate of a solid propellant is desirable to improve the design margin of solid rocket motors. A low (zero or negative) value of the pressure exponent also reduces the sensitivity of the pressure developed in the combustion chamber of the rocket motor to the initial temperature of the propellant. Quasisteady homogeneous one-dimensional (QSHOD) analy-

Energy-Intensive Materials with Mechanically Activated Components

“…The authors of [40] studied the combustion rate and flame structure of SRFs compositions with a wide particle size distribution of the starting components. However, these works focus on the size distribution of ammonium perchlorate particles and do not pay due attention to the role of the size factor of aluminum particles on the burning rate of aluminized mixed fuels.…”

Experimental study on composite solid propellant material burning rate using algorithm MATLAB

“…Solid pro pel lant [7] was pre pared by mix ing mea sured mass of ox i dizer par ti cles and binder in a proper pro por tion as shown in tabs. 1 and 2.…”

Binder melt: Composite propellants with RDX**

“…During the burning of composite propellants, the binder tends to melt and form a pool of binder on the burning surface, commonly known as binder melt [1][2][3][4]. Some of the peculiar combustion behaviour of composite propellants, such as plateau, bi-plateau burning, intermittent extinction over a range of pressures, etc., have been explained qualitatively by invoking the presence of binder melt on the surface of burning propellant [4][5][6][7][8][9][10][11]. In the open literature, there has been only one technique reported to quantify binder melt on the surface of propellant [12].…”

“…This interaction causes the pyrolysis behavior to be unstable and is the primary reason for intermittent burning. Banerjee and Chakravarthy [9] studied the AP based composite propellants with a specific coarse-to-fine ratio of AP particles. They observed plateau burning between the pressure range of 7 MPa to 10 MPa.…”