CO-EXISTING ACOUSTIC-ROTATIONAL DISTURBANCES IN A COLDFLOW MODEL OF A SOLID ROCKET MOTOR

Analytical and numerical modeling methods are used to predict the transient flow dynamics generated by time-dependen t boundary conditions in a solid rocket motor chamber model. Nonaxisymmetric, time-dependent boundary forcing on a sidewall of the cylinder, which emulates unsteady propellant gasification, is used to establish asymmetric, three-dimensional flow in a model chamber. An asymptotic analysis is used to reduce the full NavierStokes equations to a simpler set of equations, which describe the acoustic processes and the vorticity in the cylinder. The results show that the presence of a non-axisymmetric time-dependent boundary condition drives planar axial acoustics waves and a nonaxisymmetric flow response throughout the chamber. The interaction of the axial planar acoustic waves with the injected fluid produces vorticity along the sidewall of the cylinder of magnitude O(M~l). Finally, a set of rotational equations are derived to described the effect of viscosity. I Introduction