Numerical investigations of detonation cell sizes in hydrogen-methane fuel blends

Blended hydrogen-methane fuels have gained significant importance due to current power requirements and safety concerns. One major concern is increased flammability and detonability that results from increasing the amount of hydrogen. Existing detailed, chemical kinetic mechanisms for fuels are expensive and are generally unable to predict detonation ignition, propagation, and quenching accurately. Here we present the history and development of the Chemical-Diffusive Model (CDM), a reduced model for reproducing chemical and diffusion processes. We then show how the CDM has been able to overcome the challenges in predicting detonation and flame properties. The CDM parameters for hydrogen-methane blends were derived, tested, and integrated into numerical solutions of the multidimensional, compressible, reactive Navier-Stokes equations. The benefits of using the CDM in terms of quantitatively reproducing detonation dynamics at reduced computational costs are illustrated with the example of these blended hydrocarbon mixtures. Computations reproduced flame and detonation properties (including multidimensional detonation cell sizes) of  these fuel blends for a range of equivalence ratios.