Modeling of Structural Vibration for Motor Chamber Internal Flow Studies

Axial, radial and tangential structural oscillation of various propulsion system motor chamber walls is demonstrated to be able to produce substantial pressure wave amplitudes within the internal flow. Predicted resonant driving frequencies for forced rigid vibration may vary somewhat from the ideal acoustic estimate, depending on the grid density employed in the given numerical model. Similarly, predicted limiting pressure wave amplitudes may tend to asymptote somewhat higher in the case of radial and tangential structural motion, as the grid density is increased (and the corresponding time step decreased) for the numerical solver. Free dynamic structural deformation (in addition to any net rigid-body motion that might be involved) is illustrated to also have an appreciable influence on internal gasdynamic wave behavior.