Cycle-resolved flame characteristics measurement with soot in a HSDI diesel engine using micro-Cassegrain system

Abstract

In order to reduce emissions of particulate matter and nitrogen oxides by diesel engines, it is very important to understand the physics and chemistry of spray combustion in a real engine. However, most research into the characteristics of diesel spray combustion has used a constant volume combustion chamber or an optical access engine. This paper describes the combustion characteristics obtained using a micro-Cassegrain sensor and discusses how the sensor can be used to directly sense the flame characteristics for future control of diesel combustion. We connected a chemiluminescence sensor to a production diesel engine for various loads, engine speeds, and injection modes. The flame chemiluminescence of OH*, CH*, and C2* band and narrow band spectra intensity at 650 and 850 nm were measured using a new micro-Cassegrain sensor. The cylinder pressure and injection timing were also acquired simultaneously. We investigated the relationship between the radical intensities and flame characteristics and found that the intensities of the radical spectrum in a cycle changed with the load. We also demonstrated differences in the radical intensity ratios. Copyright © 2008 by the Japan Society of Mechanical Engineers.