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The exhaust plumes generated by rocket motors are of significant military importance for missile detection, recognition and communication due to their electromagnetic emission and propagation properties. The plume is a high temperature, high velocity stream of gas and particles, into which the surrounding air is entrained. With improvements in the modelling of plume gas chemistry and turbulence, particles present in the plume have become more important in the computational prediction of the plume's flow field, and the subsequent prediction of plume emission and propagation characteristics. This thesis describes research on plume particles, including the measurement of their physical characteristics and the addition of two phase coding (ie. particles) into current plume prediction software. Particle collections were carried out in plumes produced by rocket motors with double base and composite propellants (including aluminised). The collected particles were analysed to establish their chemical composition and size distribution. A laser Doppler anemometer system was successfully used to measure particle velocities in the plumes of 1.5kN double base motors. Particle tracking software was used to trace the paths of particles using a simplified prediction of the plume and it was found that the predicted particle behaviour was analogous to that measured experimentally. Project management software was used during the research and its relevance was assessed in respect to the project's size and nature. The management of experimental trials was studied and a methodology formulated to help improve their future operation. The costs and benefits of the research were assessed and compared to other research projects. Many of the benefits gained, such as measurement techniques, require marketing to ensure that they are exploited in the future. Recommendations for future research are given that should enhance the present work.

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A long hollow cylinder with five layers, subjected to a random thermal environment is analyzed. The random thermal environment includes the ambient air temperature, solar radiation and wind speed. The location of interest is Phoenix, Arizona. The governing differential equation is the so-called one-dimensional Fourier heat conduction equation in cylindrical coordinates. An implicit finite difference scheme is developed to obtain temperature responses inside the cylinder. Given the linear elastic behavior of materials involved, induced stresses and strains are evaluated at the end of each time step of the finite difference scheme. A statistical analysis is then carried out to determine the probability of failure of the propellant and hence the service life of the motor can be computed. / Ph. D.

Solid rocket motors consist of a thin metallic or composite shell filled with a soft rubbery propellant. Such motors are vulnerable and prone to buckling due to sudden external pressures produced by nearby detonation. The stability conditions of rocket motors subjected toaxisymmetric, external pressure loading are examined. The outer cases of motors are considered as isotropic (metallic) or anisotropic (composite), thin and high-strength shells, which are the main structures of interest in the stability analyses. The inner, low-strength elastic cores are modeled as linear and nonlinear elastic foundations. A general, refined, Sanders' nonlinear shell theory, which accounts for geometric nonlinearity in the form of von Karman type of nonlinear strain-displacement relations, is used to model thin-walled, laminated,composite cylindrical shells. The first order shear deformable concept is adopted in the analyses to include the transverse shear flexibility of composites. A winkler-type of linear and nonlinear elastic foundation is applied to model the internal foundations. Pasternak-foundation constants are also chosen tomodify the proposed elastic foundation model for the purpose of shear interactions. A set of displacement-based finite element codes have been formulated to determine critical buckling loads and mode shapes. The effect of initial imperfections on the structural responses are also incorporated in the formulations. A variety of numerical examples are investigated to demonstrate the validity and efficiency of the purposed theory under various boundary condiitions and loading cases. First, linear eigenvalue analysis is used to examine approximate buckling loads and buckling modes as well as symmetric conditions. An iterative solution procedure, either Newton-Raphson or Riks-Wempner method is employed to trace the nonlinear equilibrium paths for the cases of stress, buckling and post-buckling analyses. Both ring and shell-type models are applied for the structural analyses with different internal elastic foundations and initial imperfections. / Ph. D.

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The staged combustion aft-injected hybrid (SCAIH) rocket motor is a promising design for the future of hybrid rocket propulsion. Advances in computational fluid dynamics and scientific computing have made computational modelling an effective tool in design and development. The focus of this thesis is the numerical modelling of the SCAIH rocket motor in a turbulent combustion, high-speed, reactive flow accounting for solid soot transport and radiative heat transfer. The SCAIH motor has a shear coaxial injector with liquid oxygen injected centrally at sub-critical conditions: 150K, 150m/s (Mach≈0.9), and a gas-generator gas-solid mixture of one-third carbon soot by mass injected in the annual opening at 1175K, and 460m/s (Mach≈0.6). Flow conditions in the near injector region and the flame anchoring mechanism are of particular interest. Overall, the flow is shown to exhibit instabilities and the flame is shown to anchor directly on the injector faceplate with temperatures in excess of 2700K.

The staged combustion aft-injected hybrid (SCAIH) rocket motor is a promising design for the future of hybrid rocket propulsion. Advances in computational fluid dynamics and scientific computing have made computational modelling an effective tool in design and development. The focus of this thesis is the numerical modelling of the SCAIH rocket motor in a turbulent combustion, high-speed, reactive flow accounting for solid soot transport and radiative heat transfer. The SCAIH motor has a shear coaxial injector with liquid oxygen injected centrally at sub-critical conditions: 150K, 150m/s (Mach≈0.9), and a gas-generator gas-solid mixture of one-third carbon soot by mass injected in the annual opening at 1175K, and 460m/s (Mach≈0.6). Flow conditions in the near injector region and the flame anchoring mechanism are of particular interest. Overall, the flow is shown to exhibit instabilities and the flame is shown to anchor directly on the injector faceplate with temperatures in excess of 2700K.

Solid propellant rocket motors are the most widely used propulsion systems for military applications that require high thrust to weight ratio for relatively short time intervals. Very wide range of magnitude and duration of the thrust can be obtained from solid propellant rocket motors by making some small changes at the design of the rocket motor. The most effective of these design criteria is the geometry of the solid propellant grain. So the most important step in designing the solid propellant rocket motor is determination of the geometry of the solid propellant grain. The performance prediction of the solid rocket motor can be achieved easily if the burnback steps of the rocket motor are known. In this study, grain burnback analysis for some 3-D grain geometries is investigated. The method used is solid modeling of the propellant grain for some predefined intervals of burnback. In this method, the initial grain geometry is modeled parametrically using commercial software. For every burn step, the parameters are adapted. So the new grain geometry for every burnback step is modeled. By analyzing these geometries, burn area change of the grain geometry is obtained. Using this data and internal ballistics parameters, the performance of the solid propellant rocket motor is achieved. To verify the outputs obtained from this study, rocket motor tests are performed. The results obtained from this study shows that, the procedure that was developed, can be successfully used for the preliminary design of a solid propellant rocket motor where a lot of different geometries are examined.