Leung, Carlos2013-11-072013-11-0720102010Source: Masters Abstracts International, Volume: 49-03, page: 2015.http://hdl.handle.net/10393/28606http://dx.doi.org/10.20381/ruor-12622The nonlinear dynamics of one-dimensional pulsating detonations were studied numerically using a simple two-step chain branching model with separate induction and exothermic reaction zones. The stability boundary was found for a wide range of non-dimensional activation energy and heat release. The wave dynamics within the detonation structure responsible for non-linear pulsating instability were studied using the three families of characteristic curves on x-t diagrams, representing the trajectories of pressure waves and particle paths. This clarified the dynamics responsible for loss of stability and the period of the pulsating instability. Four main regimes of pulsations were observed: the high frequency, very high frequency, low frequency and transition regimes. The high and very high frequency modes tend to manifest itself for low values of activation energy, while the low frequency mode tends to appear for higher activation energy. The very high frequency pulsations are governed by a cycle of expansion waves traveling across the induction zone along the C- characteristics coupled with the compression waves traveling across the induction zone along the C+ characteristics. The high frequency pulsations are controlled by a coupling between the particle path originating from the leading shock traveling across the induction zone and the compression wave traveling across the induction zone via the C+ characteristics. The low frequency oscillations involve the C- characteristics or particle paths traveling across the entire detonation from the shock followed by the C+ characteristics traveling toward the leading shock. The mechanisms governing the pulsating instability and the periods of oscillation were found to be in good qualitative agreement with Toong's phenomenological model based on the wave dynamics in a square wave model.111 p.enEngineering, Mechanical.Thesis