| OCR Text |
Show Figure 7 shows a series of schlieren photographs representing the transient flame front deformation under acceleration[ 17] . In this case, the flame propaga tes through a methane-air mixture. The development of a local flame front disturbance could be clearly visualized. Based on this result, the flame front velocity profiles were deduced, and it was shown that the flame front at the center of the disturbance was moving at 7.5 m/ s toward the burned gas, which is much larger than the burning veloci ty[ 17]. Unburned gas must be flowing into the elongating disturbance while burned gas expands at the rim of the disturbance in a direction opposed to the elongation of the disturbance. Temperature and Species Profiles Figure 8 shows the temperature distribution of a diffusion jet flame stabilized on a 1 mm-diameter burner port measured using the system shown in Fig. 2[10]. The fuel used is a mixture of methane 32.2 % and hydrogen 67.8 %. In this case, a very short duration(about 10 ns) pulse was used, so that intrinsically the signal/noise ratio could not be increased to obtain a meaningful image. However, the potentiality of this method seems sufficient to give good quality tomographic images, which are very useful in the future research on flames. Figure 8 Temperature distribution measured using two dimensional Rayleigh thermometry shown in Fig. 2[10]. A typical interferogram representing the temperature and fuel concen tra tion distributions of a horizontal PMMA (polymethylmethacrylate) plate, irradiated by a CO2 laser beam, is shown in Fig. 9[9]. This interferogram was obtained using the system for two-wave length interferometry shown in Fig. 1. The difference between the fringe shifts for the wave length of 4416 (left) and 6328 A(right) is shown. Figure 9(b) shows the radial profiles of the temperature and the gasified fuel (MMA ) concentration near the PMMA surface deduced from the interferogram shown in Fig. 9 (a), where r represents the 8 |
