| Moving fire means fire source is in a moving state during combustion time. Domesticand foreign scholars has undertaken extensive research on the diffusion flamestructure,however,they almost all researched stationary diffusion combustion due tostationary source of fire. But in many practical circumstances, the scene of diffusioncombustion fire source is still moving. Research on moving fire is mainly premixedcombustion flame, and the flame affected by volume force such as gravity, centrifugalforce, coriolis force and so on which is mostly in closed or semi-closed environment.Research on the diffusion flame combustion of moving fire is a complement todiffusion combustion theory and it will also promote the development andimprovement of combustion. At the same time, it also has a wide range of value andguiding significance for which about efficient use of combustion or cost-effectivemitigation measures such as a fire caused by moving fire sources.A rotary motion experiment platform has been set up base on constructionrequirements about experimental study of diffusion combustion under circular motioncondition. Modern testing techniques are used in the experiment, such as high-speedvideo camera and flame image processing technology. They are used to obtain the staticand dynamic flame images, and the edge of the flame surface extraction. Experimentalresults show that within the experimental range, with the turntable speed increases,the volume force gradually increases, and the flame resistance caused by air increases,flame angle also increases. Rotating combustion flame in addition is affected by theforce, the changes in the ambient air flow is the important reason for the candle flameburning. As wheel speed increasing slowly, the flame disturbance due to airflow andair-fuel ratio increases so more air is reacted with the fuel and the burning is more andmore intense. At the same time, the flame area increases but attains the peak at thecertain rotational speed. However, when the wheel speed is continued to increase, thedisturbance of the sounding air has a negative impact on the flame burning and theflame is smaller and smaller until to extinguish because the increasing airflow takesmore heat and reduce the degree of combustion. The greater the rotation radius, thegreater impact the airflow has on the flame, the faster the flame extinguishes but thesmaller the rotational speed limitation for extinguishing has.Moving diffusion combustion under linear motion experiment in different conditions was made and the FLUENT software was also used as a numericalsimulation contrast. The research suggest that fire own movement has a greatinfluence on the flame.when wind speed is0m/s, flame form moves to the contrarydirection of fire movement and flame deflection angle will increase as the fire speedincreases. When the speed of the fire source is increased from0.36m/s to0.55m/s,flame angle will be increased from36°to60°. Flame will deflect to the same directionunder the action of wind and under the car movement when moving fire and airrelative speed is0.44m/s, but both flame shape is different, the former combustiontemperature is lower due to it dissipates more heat than the latter. Comparing with theabsolute rest combustion, relative rest combustion flame form moves to the contrarydirection of the movement of fire, and the latter combustion temperature is higher.Because the intrinsic influence and flame shape are all different, relative motionconcept can not be used to simply research the moving diffusion combustion flame.The above study of experiment and numerical simulation give a systematicunderstanding to the diffusion flame characteristics of moving fire,it provides somebasis theory for the follow-up research. |
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