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

We report the simultaneous measurement of the flamefront location, using single-shot CH planar laser-induced fluorescence (PLIF), and the velocity field, using two-color digital particle imaging velocimetry (PIV), in nonpremixed turbulent flames. To minimize the influence of particle scattering on the CH PLIF images, we pump a CH B-X(0,0) transition at 390 nm and detect A-X fluorescence at 420-440 nm, employing Schott glass filters to reject the strong particle scattering. The PIV images are recorded on a high-resolution (2036 x 3060 pixels) color CCD camera, and the velocities are derived from 64- or 128-pixel-square interrogation regions. We demonstrate this technique in a non-sooting, permanently blue nonpremixed turbulent jet flame (Re-jet = 18600). Here, PLIF images reveal a CH layer of thickness typically < 1 mm from flame base to tip. Furthermore, in these permanently blue flames, we observe instantaneous flamefront strain rates - derived from the PIV data - in excess of +/-10(4) s(-1) without flame extinction.