Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 19, 2025 - March 20, 2025
For future super-leanburn SI engines with very-high compression ratios, it is required to design a carbon-neutral fuel which could improve both combustion stability and antiknocking property. Research octane number, RON, is an antiknocking index. As RON increases, knocking limit combustion phase advances in the cylinder. The relationship between RON and ignition delay time has been investigated experimentally using shock tubes or rapid compression machines, or computationally using detailed reaction mechanisms. However, the relationship between ignition delay time and knocking limit combustion phase has been unknown. In the present study, an SI engine has been operated for different fuels with RON’s of 90 to 120. As RON increases, the heat amount from LTO decreases, and disappears at the RON of 1000. With the increase of RON, knocking limit CA50 advances straight. Then, ignition delay time has been computed under constant-volume conditions where initial pressure has been set at the in-cylinder peak pressure on the knocking limit cycle. The relationship between ignition delay time and knocking limit CA50 has been discussed. Knocking limit CA50 is dependent on in-cylinder pressure which can be initial pressure for the ignition delay time of tens of crank angle degrees with the initial temperature of 850 K to 950 K.
