International Journal of Advancements in Mechanical and Aeronautical Engineering
Author(s) : AHMAD RASHIDI, AZMI AHMAD, CHUN LOU, HAMDAN HASSAN, MOHD. HARIFFIN BOOSROH, MOOK TZENG LIM, NOOR AKMA WATIE MOHD NOOR, SOONG DER CHEN
Flame speeds are important flame characteristics in combustion processes as it determines the stability of the flame. Accurate experimental measurements of flame speeds require optical systems and diagnostic instruments, such as those in schlieren photography. However, these systems are more suitable in laboratory environments. In industrial furnaces, simpler methods are required to determine the flame speeds for comparison. Infrared cameras are used to detect ‘hot spots’ in furnaces, and since the radiation intensity of the flame is indicated by the brightness of the pixels in the images, a sequence of images can be used to determine the difference in the pixels’ brightness, allowing determination of the flame’s movement and subsequently the flame speed. Thus, in this study, a tool to determine the flame speeds using an image processing technique is presented. Preliminary results of the flame speeds from a 150 kWth coal fired combustion test rig were obtained. The combustion test rig contains a moveable block that imparts a swirling flow with a swirl number of 2.0. Infrared images were recorded for liquid petroleum gas (LPG) flames and coal-flames. The approximated flame speeds show that the coal flames are highly fluctuating compared to liquid petroleum gas flames. This may be caused by the inertia of the coal particulates that have increased the turbulence of the gas flow.