## 2 Experiment Details  
A schematic representation of the experimental optical set-up is shown in Figure 1a. The laser system consisted of a pulsed Nd: YAG laser pumping a dye laser circulating rhodamine 590 dye in methanol. The dye laser light was frequency doubled to yield about 1.8 mJ/pulse at a frequency of 400 Hz. The laser wavelength, 283.599 nm, was calibrated by wavemeter (WaveMaster, Coherent, CA, USA), corresponding to 283.553 nm; this was used to excite the \(Q_{1}(8)\) line of the (0,1) band of the OH (\(X^{2}\Pi-A^{2}\Sigma^{+}\)) system. The OH transition was confirmed to give off a strong fluorescence signal relative to neighboring transitions, which was particularly suitable for this complex environment [20]. In the experiment, the observation windows were extremely vulnerable to oil contamination, which greatly increased the difficulty of excitation and detection. Laser energy can be seriously affected by the external environment, especially temperature and humidity. The temperature in the factory fluctuated within the range of 25-35 \({}^{\circ}\)C. In addition, factory humidity reached 90%, resulting in fluctuation of laser energy and drift of the laser wavelength. More seriously, the harsh environment will affect the stable operation of the PLIF system. High temperatures can affect the thermal effects of the laser crystal, and reduce frequency-doubling efficiency, while high humidity may cause crystal deliquescence. It is worth mentioning that the pumping source was developed independently for the PLIF system to overcome complex experimental environment. The pumping source was filled with nitrogen to prevent moisture accumulation. Finally, anti-vibration measures were also considered. In order to meet the engineering needs, a large size sheet light is needed. The optics consisted of a concave lens (f = \(-\)8 mm), collimating lens (f = 240 mm), and focus lens (f = 800 mm). The sheet forming optics generated a nearly 10.5 cm laser sheet, and the sheet reaching the observation window was nearly 12.3 cm. The sheet-forming optics system spread the laser beam into a collimated 12.3 cm (width) laser sheet. Subsequently, the distribution of sheet energy was not uniform, as calculated. The fluorescence from part of the illuminated sheet was recorded with an intensified CMOS camera (EoSens(r) CXP, MIKROTRON, Unterschleissheim, Germany). The combination of simrock 315/15 and UG11 mounted in front of the ICMOS camera was used to block flame spontaneous radiation and laser scattered light. In consideration of the signal-to-noise ratio of the images, the exposure time was fixed at a value of 30 ns. The camera has a maximum frame rate of 10 KHz, and the COMS array was 1000 \(\times\) 1000 pixels. In the experiment, the ICMOS camera imaged a 110 \(\times\) 110 mm\({}^{2}\) area of the combustion field, giving a spatial resolution of about 110 um per pixel. In contrast to a laboratory burner, industrial-type burners possess relatively complex control systems. More specifically, the ignition delay and control line delay fluctuation represent obstacles in the detection of the evolution of the flame structure. The experimental timing is controlled by digital delay generator (DG645, Stanford Research Systems, Sunnyvale, CA, USA), with 5 pm accuracy. In the experiment, the trajectory of the wrinkled structure and velocity of the flame surface depend on the pixel positions. In Figure 2, for the trajectory of the wrinkled structure, we chose the top B. For the trajectory of flame surface A, we chose the center of the flame surface A. As the flame surface had a certain thickness, we chose the brightest position of the flame surface center, which represents the most violent combustion. The velocity of the flame surface can be obtained by changing the pixel positions of the same structure of the two images; the time of two images is 2.5 ms. The experiment was repeated many times under specific working conditions. Although only typical images are shown in the paper, the results proved consistent.