Gasturbines@SNU

  There are different pathways that fuel and oxidizer molecules are able to go through, and most of these reactions involve collision between them. After a moment radicals, which are very unstable species coming out from collision, are formed in large quantity and they induce consecutive reactions. Whole process of these chained reactions is called “combustion” when it is observed in global point of view. It takes a moment for the massive formation of radical species nevertheless high temperature and pressure conditions provide enough energy for the collision of molecules. Duration for the massive radical formation may vary with conditions such as type of fuel, temperature, concentration, equivalence ratio, etc. This duration is called “ignition delay” and often acknowledged as a factor of reactivity. Rapid compression machine (RCM) is designed to compress the mixture instantly, generating high temperature and pressure conditions via polytropic compressing process and thereby inducing the reaction of test gas. Compressed temperature and pressure may vary with initial conditions, so that ignition delay of the mixture under desired state could be measured directly. Mapping these data with respect to temperature and pressure conditions enables inspecting the reactivity of the gas.