Experimental study of the spray ignition characteristics of hydro-processed renewable jet and petroleum jet fuels in a constant volume combustion chamber

In this study, the spray ignition characteristics of conventional aviation fuels (JP-5 and Jet-A1) and hydroprocessed renewable jet fuel (HRJ) were investigated in a constant volume combustion chamber at chamber pressures of 10, 15, and 20 bar and temperatures ranging from 600 K to 818 K. It was found that all the ignition delays profile were shortened exponentially with increases in the chamber temperature. The HRJ fuel was found to obtain a shorter ignition delay as compared to JP-5 and Jet-Al by as much as 74% and 67%, respectively. In addition, the first stage ignition delay for HRJ fuel was 50% shorter than that for the petroleum jet fuels. The reactivity of the fuels increased with increases in the chamber pressure. The HRJ fuel was 1 ms and 2 ms earlier than Jet-A1 and JP-5, respectively, in terms of achieving a combustible mixture at low and intermediate chamber pressures. The chamber pressure was also found to be sensitive to the formation of the NTC zone for all of the tested fuels.