Reduced Order Chemistry Modeling for Detonations
Alexandra Baumgart, California Institute of Technology
Physically accurate detonation models are critical to a variety of applications, including safety in nuclear or chemical plants and efficient energy generation for propulsion. Due to the range of physics involved (shock waves, turbulence, chemistry, etc.), large scale simulations are often impractical unless simplifying assumptions are made. Unfortunately, current approaches to chemistry modeling for detonations involve a tradeoff between computational efficiency and physical accuracy. To reduce the cost of simulations without neglecting the physics, tabulated chemistry models are often used for flames. In this model, a progress variable is transported in the simulation to describe the progress of chemical reactions from unburnt (reactants) to burnt (products). This progress variable is used to look up all other transport properties, thermodynamic variables, and chemical source terms from a pre-computed table. The present work extends the tabulated chemistry method to detonations. Temperature is selected as a second table coordinate to capture large variations in the thermodynamics, and one-dimensional detonations are used to pre-compute the lookup table. The approach is validated for one- and two-dimensional detonations in various hydrogen-oxygen mixtures. The tabulated chemistry simulations are able to reproduce the detailed chemistry results at a much lower computational cost.