Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009. / Full text also available online. Scroll down for electronic link.

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The subject investigation demonstrated that it is feasible to use the microwave technique to measure radial burning rates ,and differential burning rates in solid propellant rocket motors. A simulator, consisting of a spiral rotating in an oil bath, was used to represent the curved burning surface of a tubular grain of propellant with the outer surface and ends restricted. The radial movement of the spiral, simulating radial burning, was detected by recording the phasor difference of the reflected microwaves from the reflecting surface of the spiral and the reflected microwaves from a stationary reference surface. The reflected microwaves changed in phase relation producing successive minimum values in the detected signal for each one-half of a microwave wavelength in oil displacement of the spiral. The displacement rates were calculated as average rates for a displacement of one-half of a microwave wavelength in oil. The curved reflective surface did not present a measurement problem. The differential displacement rates were detected by recording the phasor difference of the reflected signals from two spirals. The reflected signals changed in phase relation, if the reflecting surfaces were moving at different rates, producing a beat frequency in the detected signal. The differential displacement rate was determined from the number of beat frequency cycles, the one-half microwave wavelength in oil, and the time. The addition of the aluminum powder to the oil simulating aluminized propellants did not prevent detection of the moving surface. The results indicated that the microwave technique can be applied to aluminized propellants. / M.S.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 49-53).

The following dissertation describes an investigation of the structural response behaviour of a composite solid rocket motor nozzle subjected to thermal and pressure loading during the motor ignition period, derived on the basis of a multidisciplinary numerical simulation approach. To provide quantitative and qualitative context to the results obtained, comparisons were made to the predicted aerothermostructural response of the nozzle over the entire motor burn period. The study considered two nozzle designs – an exploratory nozzle design used to establish the basic simulation methodology, and a prototype nozzle design that was employed as the primary subject for numerical experimentation work. Both designs were developed according to fundamental solid rocket motor nozzle design principles as non-vectoring nozzles for deployment in medium sized solid rocket booster motors. The designs feature extensive use of spatially reinforced carbon-carbon composites for thermostructural components, complemented by carbon-phenolic composites for thermal insulation and steel for the motor attachment substructures. All numerical simulations were conducted using the ADINA multiphysics finite element analysis code with respect to axisymmetric computational domains. Thermal and structural models were developed to simulate the structural response of the exploratory nozzle design in reference to the instantaneous application of pressure and thermal loading conditions derived from literature. Ignition and burn period response results were obtained for both quasi-static and dynamic analysis regimes. For the case of the prototype nozzle design, a flow model was specifically developed to simulate the flow of the exhaust gas stream within the nozzle, for the provision of transient and steady loading data to the associated thermal and structural models. This arrangement allowed for a more realistic representation of the interaction between the fluid, thermal and structural fields concerned. Results were once again obtained for short and long term scenarios with respect to quasi-static and dynamic interpretations. In addition, the aeroelastic interaction occurring between the nozzle and flow field during motor ignition was examined in detail. The results obtained in the present study provided significant indications with respect to a variety of response characteristics associated with the motor ignition period, including the magnitude and distribution of the displacement and stress responses, the importance of inertial effects in response computations, the stress response contributions made by thermal and pressure loading, the effect of loading condition quality, and the bearing of the rate of ignition on the calculated stress response. Through comparisons between the response behaviour predicted during the motor ignition and burn periods, the significance of considering the ignition period as a qualification and optimisation criterion in the design of characteristically similar solid rocket motor nozzles was established. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

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