We have recently been studying autoignition of natural gas mixtures in an internal combustion engine context. We are motivated by the possibility that natural gas could be used as an alternate fuel in heavy duty applications, with substantial benefits in terms of pollutant emissions. We are starting to understand that fluctuations in the autoignition delay time of even initially homogeneous mixtures are possible due to the random nature of inter-molecular collisions at the earliest stages of the ignition process. These fluctuations can have a severe impact on our ability to control engines, particularly as we try to push the engine to operate at more extreme conditions to minimize pollutants.

The talk will start with an overview of the evidence we have that fluctuations in the ignition delay time are indeed significant. A relatively new method for predicting these fluctuations using a Monte Carlo method will then be presented and results from this method will be discussed. The talk will conclude with some prospects for future uses of this technique.