No description available.

No description available.

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.

A method for developing an erosive burning model for use in solid propellant design-and-analysis interior ballistics codes is described and evaluated. Using Direct Numerical Simulation, the primary mechanisms controlling erosive burning (turbulent heat transfer, and finite rate reactions) have been studied independently through the development of models using finite rate chemistry, and infinite rate chemistry. Both approaches are calibrated to strand burn rate data by modeling the propellant burning in an environment with no cross-flow, and adjusting thermophysical properties until the predicted regression rate matches test data. Subsequent runs are conducted where the cross-flow is increased from M=0.0 up to M=0.8. The resulting relationship of burn rate increase versus Mach Number is used in an interior ballistics analysis to compute the chamber pressure of an existing solid rocket motor. The resulting predictions are compared to static test data. Both the infinite rate model and the finite rate model show good agreement when compared to test data. The propellant considered is an AP/HTPB with an average AP particle size of 37 microns. The finite rate model shows that as the cross-flow increases, near wall vorticity increases due to the lifting of the boundary caused by the side injection of gases from the burning propellant surface. The point of maximum vorticity corresponds to the outer edge of the APd-binder flame. As the cross-flow increases, the APd-binder flame thickness becomes thinner; however, the point of highest reaction rate moves only slightly closer to the propellant surface. As such, the net increase of heat transfer to the propellant surface due to finite rate chemistry affects is small. This leads to the conclusion that augmentation of thermal transport properties and the resulting heat transfer increase due to turbulence dominates over combustion chemistry in the erosive burning problem. This conclusion is advantageous in the development of future models that can be calibrated to heat transfer conditions without the necessity for finite rate chemistry. These results are considered applicable for propellants with small, evenly distributed AP particles where the assumption of premixed APd-binder gases is reasonable.

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.

No description available.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 83-85).

M.S.

The object of this investigation was to develop a general solution for the thermal stresses and strains in a hollow cylindrical case-bonded solid propellant. The heat conduction equation, as solved by Carslaw and Jaeger, was applied to a hollow composite cylinder. The temperature distribution from this equation was used in conjunction with the stress and strain for an elastic solid propellant. The boundary conditions were employed to solve for the constants and the general solution for the stresses and strains were obtained. In order to study the predictions of the general expressions, a numerical example was presented. It was found that the maximum stress and strain appeared at the inner radius of the grain. It was also observed that the stress and strain increased with an increase in the radius ratio "m”. Failure criteria for the grain under consideration were discussed. A method for obtaining the maximum allowable temperature variation (from cure temperature) was investigated. Knowing the stress and strain characteristics of the grain the equations developed would indicate failure conditions and also allow calculations of the maximum allowable temperature variations prior to grain failure. / M.S.