Simultaneous CH planar laser-induced fluorescence and particle imaging velocimetry in permanently blue nonpremixed turbulent jet flames

We report simultaneous measurement of the flamefront location, using CH planar laser induced fluorescence (PLIF), and the velocity field, using two-color digital particle imaging velocimetry (PIV), in nonsooting, permanently blue nonpremixed turbulent jet flames. To minimize the influence of particle scattering on the CH PLIF images, we pumped a CH B-X(0,0) transition at 390 nm and detected A-X fluorescence at 420-440 nm, employing colored glass to filter out the strong particle scattering. The PIV image was recorded on a high-resolution (2036x3060 pixels) color CCD camera, and the velocities were derived from 64- or 128-pixel-square interrogation regions. PLIF images reveal a CH layer thickness that is less than or equal to 1 mm from flame base to tip. Furthermore, in these permanently blue flames, we observe instantaneous flamefront strain rates in excess of +/-10,000 s(-1) without flame extinction.