1. Research background and significance
In the field of safety engineering, the speed and characteristics of flame propagation directly affect the spread of fire and the degree of harm. Among them, the propagation dynamics mechanism of blue flames is a core issue in fire safety research because of their full combustion and high temperature. Traditional image acquisition equipment is not sensitive enough in weak light (quantum efficiency <30%), making it difficult to capture the transient behavior of blue flames. With its high quantum efficiency, low readout noise, and high dynamic range, sCMOS scientific cameras can effectively capture subtle changes and transient behaviors of flames, helping to study the propagation mechanism of blue flames.
Recently, engineers from Revealer Technology and researchers from a safety engineering laboratory jointly conducted an observation experiment based on an sCMOS scientific camera .
2. Experimental equipment
1) sCMOS scientific camera : Revealer Gloria 4.2, derived from GSENSE2020BSI chip, with a resolution of 2048×2048 and a quantum efficiency of >70% at 410nm.
2) Combustion experimental device, with a size of 1.2m×0.8m×0.6m, which can ensure the stability and repeatability of combustion by adjusting the oxygen volume fraction in the combustion environment and simulating oxygen-rich conditions. 3) Bandpass filter, with a central wavelength of 410nm and a half-width of 10nm, is used to suppress background spectral interference and improve the signal-to-noise ratio. 4) Scientific imaging analysis software RPC, used to collect and store image data obtained by the sCMOS scientific camera in real time.
3. Experimental process and data
1) Premix methane-oxygen, equivalence ratio Φ=0.9, flow rate 5L/min, oxygen concentration gradient 25%~35%.
2) Set up a sCMOS scientific camera at the side ignition system of the combustion device, with a 50mm C-mount lens, and install the filter in front of the camera lens.
3) Adjust the focus and aperture of the sCMOS scientific camera, increase the exposure time and gain, and ensure that the burning area is clearly captured.
4) LabView is used to control the synchronization of ignition, gas supply and scientific camera, and the synchronization error is less than 50μs.
5) Change the oxygen concentration experimental conditions and obtain image data of blue flame under different conditions.
binarization analysis method, the researchers extracted the edge contour of the blue flame, calculated the displacement of the flame at different time points based on the extracted flame edge position information, and further calculated the propagation speed of the blue flame.
The original image captured in the experiment clearly shows the wrinkle area of the flame. By adjusting the experimental conditions, it was found that under oxygen-rich conditions, the displacement speed of the blue flame was significantly higher than that of the flame under normal air conditions, and flashover was prone to occur during the propagation process.
4. Experimental Conclusions and Prospects
In this experiment, the sCMOS scientific camera has a good response in the ultraviolet and blue light bands, revealing the microscopic dynamic mechanism of oxygen-rich flames and providing intuitive and detailed image data for studying the propagation mechanism of flames. The researchers will subsequently combine AI algorithms to develop a flame semantic segmentation model based on the U-Net model to improve the diagnostic efficiency under complex backgrounds and provide stronger theoretical support and technical guarantee for precise prevention and control in the field of fire safety engineering.
