Scale Effects on Solid Rocket Combustion Instability Behaviour

The ability to understand and predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. A numerical model incorporating pertinent elements, such as a representative transient, frequency-dependent combustion response to pressure wave activity above the burning propellant surface, is applied to the investigation of scale effects (motor size, i.e., grain length and internal port diameter) on influencing instability-related behaviour in a cylindrical-grain motor. The results of this investigation reveal that the motor’s size has a significant influence on transient pressure wave magnitude and structure, and on the appearance and magnitude of an associated base pressure rise.

Scale Effects on Solid Rocket Combustion Instability Behaviour

The ability to understand and predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. A numerical model incorporating pertinent elements, such as a representative transient, frequency-dependent combustion response to pressure wave activity above the burning propellant surface, is applied to the investigation of scale effects (motor size, i.e., grain length and internal port diameter) on influencing instability-related behaviour in a cylindrical-grain motor. The results of this investigation reveal that the motor’s size has a significant influence on transient pressure wave magnitude and structure, and on the appearance and magnitude of an associated base pressure rise.

An Improved Modeling of Solid Propellant Fracturing to Produce Long Fractures in Wellbore Formations

Simultaneous ignition of an entire exposed surface required for accurate modeling of solid propellant fracturing process is difficult to achieve because wellbore fluids decrease flame spread rate and negatively impact burn propagation, and can extinguish portions of the burning propellant grain thereby resulting in slower pressure loading rates and insufficient energy for producing long fractures. A proposed system is that in which the propellant is protected from wellbore fluids by housing it in a vessel with a means for creating openings to allow combustion gases produced to flow into the wellbore. On this basis, a model was developed using mass and energy conservation laws, and applying a concept of choked flow in the openings to relate conditions in the wellbore to the vessel. The results of the peak pressure and pressure rise time obtained from the model for multiple-fracture regime agree well with the reported experimental results and thus establishing the validity of the model in predicting the wellbore pressure during solid propellant fracturing system. A star-shape burning surface is proposed for the propellant and calculations carried out proves it to be more effective as it provides more energy for producing long fractures essential for more flow of oil and gas from the reservoir into the wellbore than a conventional circular surface of the same burning area. The exterior angle of star-shape burning surface was found to be a function of the number of vertices of the star and it determines the progressive burning nature of the propellant.

Mathematical modeling of agglomerates evolution

The model of evolution of the condensed products as a part of a flow of combustion products of solid propellant is developed. The model includes the description of physical and chemical transformations for two basic fractions of the condensed products: agglomerates and smoke oxide particles (SOPs). Model testing is carried out using experimental data about evolution of the condensed products for two compositions in the conditions of a one-dimensional flow. These compositions differ considerably in properties of combustion products at a surface of burning propellant. The results of testing give the grounds to draw a conclusion about high enough quality of modeling.

Parameters Affecting the Erosive Burning of Solid Rocket Motor

Increasing the velocity of gases inside solid rocket motors with low port-to-throat area ratios, leading to increased occurrence and severity of burning rate augmentation due to flow of propellant products across burning propellant surfaces (erosive burning), erosive burning of high energy composite propellant was investigated to supply rocket motor design criteria and to supplement knowledge of combustion phenomena, pressure, burning rate and high velocity of gases all of these are parameters affect on erosive burning. Investigate the phenomena of the erosive burning by using the 2’inch rocket motor and modified one. Different tests applied to fulfil all the parameters that calculated out from the experiments and by studying the pressure time curve and erosive burning phenomena.