Date of Award

Spring 2004

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Majdalani, Joseph

Second Advisor

Nigro, Nicholas

Third Advisor

Heinrich, Stephen

Abstract

Internal flowfield modeling is a requisite for obtaining critical parameters for the design and fabrication of modern solid rocket motors. In this work, the analytical formulation of internal flowfields particular to solid rocket motors with tapered sidewalls is pursued. The analysis employs the vorticity-stream function approach to treat this problem assuming steady, incompressible, inviscid, isothermal and non-reactive flow conditions. The resulting solution is rotational and inviscid following the analyses presented by Culick for a cylindrical solid rocket motor. In an extension to Culick's classic work, Clayton has recently managed to incorporate the effect of tapered walls. A similar approach to that of Clayton will be applied to the slab motor in which the chamber will be modeled as a rectangular channel with porous, tapered sidewalls. The solutions will be shown to be reducible, at leading order, to Taylor's inviscid profile in a channel and to Culick's profile in a cylinder, respectively. The analysis also captures the generation of vorticity at the surface of the propellant and its transport along the streamlines due to axial pressure gradients. It is from the axial pressure gradients that the proper form of the vorticity is ascertained. The method of regular perturbations is used to solve the nonlinear vorticity equation that prescribes the mean flow motion in tapered geometries. Subsequently, numerical results provided by FLUENT™ are used to aid in the validation of the analytical approximations obtained in this study. To further understand the effects of the taper on flow conditions, comparisons of total pressure and velocity profiles in tapered and non-tapered chambers are entertained. In pursuit of a complete and concise study, Clayton's analytical work is revisited here and presented with different results. This study constitutes a small step in improving our current modeling capabilities of internal flows in chambers with variable cross section.

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