(3-23) Detailed Spectrum Analysis of Chemiluminescent Radicals at Flame Front in an SI Engine((D-3)Diagnostics 3-Applications and Advamced Technolog)

Abstract

Local chemiluminescence emission intensities of OH^*, CH^*, and C_2^* were measured at points within an 125-cc two-stroke optical engine, cassegrain optics device was used to detect the local chemiluminescence intensity at the flame front. Figure 1 shows an example of a instantaneous flame image. Time-resolved optical multi-channel analyzer (OMA) measurements at the flame front, as shown in Fig. 2, indicate that the spectrum intensity profile of the radicals persists when a flame front is passing the measurement volume determined by cassegrain optics. The tendency was similar at different engine speeds, slowing a constant peak radical intensity ratio at the preset engine condition with the throttle 20% open. In addition, a monochrometer was used to investigate the characteristics of flame emission. Spectrum-resolved analyze was applied to the detailed spectra of each chemiluminescent radical. As indicated in Fig. 3, the CH^* spectra at three different engine speeds are the same as that of a CH_4 laminar flame, this information can be used to develop a better chemical kinetics model for SI engine combustion.