THE STABILITY OF IMPLODING DETONATIONS - RESULTS OF NUMERICAL SIMULATIONS

The relative stability of cylindrically imploding shock and detonation waves has been examined using a two-dimensional numerical model. A se quence of increasingly realistic chemistry models is used to explore t he effect of model selection on the results. Comparisons with the pred ictions of Chester-Chisnell-Whitham (CCW) theory for the acceleration of nonreactive shocks and detonations show quantitative agreement betw een theory and simulation for symmetrically imploding waves. The influ ence of structural supports in laboratory experiments on the symmetry of imploding waves is simulated by placing an obstacle in the path of the converging flow. Changes in the convergence time, reductions of th e peak pressure at implosion, and deviations from symmetry during the implosion induced by the obstacle are greater for detonations than for the corresponding nonreactive shocks, in qualitative agreement with t he linearized CCW theory for shocks and Chapman-Jouguet detonations. T hese conclusions continue to hold when more sophisticated Zel'dovich-v on Neumann-Doering or finite-rate chemistry models are assumed. For th ese models, a substantial amount of new asymmetrical, dynamical struct ure is evident in the reaction zone behind the leading shock. The resu lts concur with and extend previous theoretical work suggesting that i mploding detonation waves are relatively more unstable than nonreactiv e shocks.