Analysis of flame characteristics of low calorific value gas diffusion combustion under the action of thermal dynamics

In this paper, the flame characteristics of co-axial concomitant flow diffusion combustion of low calorific value gas under the action of thermal dynamics are studied. Based on Fluent software, the combustion process of low calorific value gas is simulated by a finite element volume method. According to different air preheating temperatures Ta-in, by analyzing the changes of temperature field, velocity field and concentration field during combustion and solving the curve fitting equation of velocity field, the changing trend of the flame core, inner flame and outer flame with air preheating temperature is obtained. The results show that the flame front temperature decreases with the increase of Ta-in when low calorific value gas is burned; the flame core and the inner flame length shorten with the increase of Ta-in. When Ta-in rises from 300 K to 500 K, the flame core and the inner flame shorten by 0.05584 and 0.05867 m respectively, with the increase of Ta-in, the length of the flame outer flame increases first and then decreases. when Ta-in = 350K, the flame outer flame is the longest with the maximum value of 0.78865 m m. When Ta-in = 350K, The Y-max value corresponding to the zero-boundary point position of the equivalence ratio of combustion reaction is the largest, and the maximum value is Y-max = 0.0328m. Therefore, when Ta-in = 350K, the flame outer flame length is the longest, the mixing area of combustible gas and air is the largest, the flame front temperature is higher during combustion, and the combustion effect is the best.