Numerical Investigation of the Ignition Delay Time of Kerosene Premixed Combustion in an SI Engine

Abstract

SI engines are installed widely in small aircrafts as they have good fuel economy. Currently, these SI engines are fueled with gasoline, although their safety can be improved if kerosene is used. However, the combustion performance of kerosene cannot fulfil the requirements due to the differences in physicochemical properties. This study investigates the ignition delay time of kerosene at a pressure range of 15–35 bar and a temperature range of 600–1000 K. A detailed chemical reaction mechanism is employed for the premixed combustion process. Under the initial conditions of 1000 K and 35 bar, with an equivalence ratio of 1, the total ignition delay time of kerosene is 0.401 ms. The NTC range of kerosene is determined as roughly 750–920 K. Subsequently, the chemical reaction paths with an equivalence ratio of 0.8, 1, and 1.2 and an initial pressure of 15, 20, and 25 bar were analyzed. The rate-determined elementary reactions were obtained based on a sensitivity analysis. The difference between kerosene and gasoline are also compared, and the rate-determining reactions that affect the ignition of kerosene and gasoline are discussed. The results of this study can provide a reference for the combustion performance improvement and knock suppression of SI engines fueled with kerosene.

Effects of Hydrogen Addition on Premixed Combustion of Kerosene in SI Engine

“…Table 2 lists the main elementary reactions for the premixed combustion of kerosene and hydrogen. Compared with pure kerosene shown in [42], reactions R5 (KERO-OO = KERO#OOH), R6 (KERO#OOH + O 2 = OOKERO#OOH), R4 (KERO-+ O 2 = KERO-OO), and R72 (H 2 O 2 + OH = HO 2 + H 2 O) are removed, while the importance of R78, R32, and R67 rises. R6 and R4 are two oxygenation reactions, and R5 is the isomerization of the product of R4.…”

“…The operation conditions are configured according to the measured data from a Rotax 914 engine with kerosene [42,43]. The working temperature is set to 600-1000 K and the pressure is in the range of 15-35 bar.…”

“…Although there are some investigations about hydrogen addition, few have explored the premixed combustion of kerosene. In [42], the authors investigated the ignition characteristics of kerosene in an aviation SI engine. In [43], water injection was employed to suppress knock of an SI engine fueled with kerosene.…”