A comprehensive analytical model which considers time and space development of the flow field in solid propellant rocket motors with high volumetric loading density is described. The gas dynamics in the motor chamber is governed by a set of hyperbolic partial differential equations, that are coupled with the ignition and flame spreading events, and with the axial variation of mass addition. The flame spreading rate is calculated by successive heating-to-ignition along the propellant surface. Experimental diagnostic studies have been performed with a rectangular window motor (50 cm grain length, 5 cm burning perimeter and 1 cm hydraulic port diameter), using a controllable head-end gaseous igniter. Tests were conducted with AP composite propellant at port-to-throat area ratios of 2.0, 1.5, 1.2, and 1.06, and head-end pressures from 35 to 70 atm. Calculated pressure transients and flame spreading rates are in very good agreement with those measured in the experimental system.

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Starting Transient of Solid-Propellant ocket Motors with High Internal Gas Velocities

The balance equations for heterogeneous two-phase reacting flow are deduced by a formal averaging procedure. The equations are compared with alternatives which have been reported in the literature for the study of convective burning in porous beds. Errors in the latter are noted by reference to simple limiting case arguments. The empirical data required to support the balance equation are discussed. The balance equations are shown to be hyperbolic but not totally hyperbolic. Two methods of numerical solution of unsteady quasione-dimensional two-phase flow with discontinuous distributions of porosity are described. Bj,B2,B3 c »P e <Fy fs ^ r n Pr P q

Modeling Heterogeneous Two-Phase Reacting Flow

Effect of magnesium on the burning characteristics of boron particles

The role of gas permeation in convective burning

Modelling of two-phase transient flow and combustion of granular propellants

: Ultra-high burning rates can be achieved by combustion of porous media. A theoretical model is developed to describe the flame propagation in a packed bed of granular propellant. The calculated pressure-time-distance transients, wave propagation speed, and mass fraction of propellant burned during flame propagation, all agree well with experimental data obtained for the same conditions. Results demonstrate that the combustion-generated strong pressure gradient causes the hot product gas to deeply penetrate the unburned region. A continental divide forms automatically in the pressure distribution as the wave progresses into the charge. In the particular case studied the flame front reaches a speed about 5000 times the normal propellant burning rate and continues to accelerate as the internal pressure increases. (Modified author abstract)

Theory of Flame Front Propagation in Porous Propellant Charges under Confinement

The starting transient of solid propellant rocket motors with high internal gas velocities. Ph.D. Thesis

Solid rocket performance during rapid pressure excursions differs greatly from predictions based on steady-state burning rate data. Rapid pressurization (150-250 kpsi/sec) following a sudden throat area decrease in a low L* combustor produces pressure overshoots of 10% and indicated burning rate overshoots in excess of 50%. A transient internal ballistics model was developed incorporating nonsteady continuity and energy equations for the chamber, nonsteady energy equation for the propellant condensed phase, and a modified Zeldovich heat feedback function for the propellant (which for the conditions considered is known to burn with a thin quasi-steady reaction zone). Sensitivity analyses using the model indicate that accurate surface temperature and temperature sensitivity data are needed. With reasonable estimates of surface reaction zone temperature and measurements of temperature sensitivity of burning rate, good agreement between the measured and the calculated p vs t was found for a nonmetallized composite propeliant in a low L* combustor. High pressure exponent, high temperature sensitivity of burning rate, high dAJdt, low burning rate, and low L* prominently increase the dynamic effects.

Dynamic Responses of Solid Rockets during Rapid Pressure Change

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K. K. Kuo

Papers

Starting Transient of Solid-Propellant ocket Motors with High Internal Gas Velocities

Theory of Flame Front Propagation in Porous Propellant Charges under Confinement

The starting transient of solid propellant rocket motors with high internal gas velocities. Ph.D. Thesis

Dynamic Responses of Solid Rockets during Rapid Pressure Change

The starting transient of solid-propellant rocket motors with high internal gas velocities.