Browse Publications Technical Papers 2020-01-0338

Effect of Changing Compression Ratio on Ignition Delay Times of Iso-Octane in a Rapid Compression Machine 2020-01-0338

Previous studies have shown that several facility dependent factors can influence ignition delay times measured in a rapid compression machine. Compression ratio variation represents one such aspect of many facility-to facility differences in RCMs, and can have a major impact on measured ignition delay times due to changes in surface-area-to-volume ratio, initial conditions and compression duration even when the same compressed conditions are maintained. In this study, iso-octane, which exhibits two stage ignition delay and has a pronounced negative temperature coefficient (NTC) region, is used to investigate the effects of changing compression ratio on ignition delay. Resulting trends are also compared to previous results obtained with ethanol, which has very different combustion properties. Experiments were carried out for rich mixtures (ϕ = 1.3) of iso-octane and air over a compressed temperature range of 675-900 K at 20 bar compressed pressure. Two compression ratios are considered for each case with initial temperature and pressure adjusted in conjunction to achieve the identical compressed condition. The compression ratio was varied from 6.8 to 17.1 which also led to changes in initial conditions, compression time and surface area-to-volume ratio, all of which together affected the ignition delay time at a given compressed condition.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Optical Diagnostics of Isooctane and n-Heptane Isobaric Combustion


View Details


Expansion of the Operating Range with In-Cylinder Water Injection in a Premixed Charge Compression Ignition Engine


View Details


PLIF Measurements of Fuel Distribution in a PFI Engine Under Cold Start Conditions


View Details