A reduced stochastic model for shock and detonation waves – p. 1

As pulse detonation engine development matures, it becomes increasingly important to consider how practical details such as the implementation of valves and nozzles will affect performance. Inlet valve timing and valveless inlet designs may result in flow of products back upstream and, consequently, reduction in impulse over the ideal case. Although proper inlet design or operation under flowin...

The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈ 0.5 − 4 days. In addition, the composite lightcurves formed from stacking together many Type Ia supernovae (SNe Ia) show a similar power-law index of 1.8±0.2 with time. I explore what range of power-law rises are possible due to the presence of radioactive material near the sur...

The propagation of detonations through several fuel-air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that o...

The objective of theoretical, computational and experimental studies outlined in this lecture note was to evaluate the design principles and propulsion performance of prospective air-breathing engines operating on pulse detonations of realistic hydrocarbon fuels with a realistic technique of detonation initiation via deflagration-to-detonation transition (DDT). 1.0 INTRODUCTION Activities in th...

A combustion model which captures the interactions among nonlinear convection, chemical reaction and radiative heat transfer is studied. New phenomena are found with radiative heat transfer present. In particular, there is a weak detonation solution for each radiative heat loss coeecient. The speed of the weak detonation wave decreases as the heat loss coeecient increases and the detonation wav...

We present results of a linear stability analysis of relativistic detonation fronts, which have been considered as representing phase interfaces in cosmological first order phase transitions. After discussing general stability conditions for detonation fronts, we concentrate on the properties of the fronts with respect to corrugation instabilities and discuss separately the cases of Chapman-Jou...

We investigate hydrodynamic instability of a steady planar detonation wave propagating in a circular tube to three-dimensional linear perturbations, using the normal mode approach. Spinning instability is identified and its relevance to the well-known spin detonation is discussed. The neutral stability curves in the plane of heat release and activation energy exhibit bifurcations from a low-fre...

Detonation of the flow of a combustible mixture over a wedged channel is numerically simulated. A two-dimensional, time accurate, finite-volume-based method is used to perform the computations, and a five-species, two-step chemical reaction is assumed for a stoichiometric hydrogen-air mixture. The combustion channel is made of a wedged section followed by a constant area section. The simulation...

The effectiveness of imploding waves at detonation initiation of stoichiometric ethyleneand propane–oxygen– nitrogen mixtures in a tube was investigated. Implosions were driven by twice-shocked gas located at the end of a shock tube, and wave strength was varied to determine the critical conditions necessary for initiation as a function of diluent concentration for each fuel. Hydrocarbon–air mi...