Investigating the effect of changing the length of the blades of a low-swirl burner on the flow field in a premixed flame

In this research, the objective was to investigate the impact of altering the length of low-swirl burner blades within a premixed flame. To achieve this, two types of swirler, one with four blades and another with eight blades, both featuring a radius of 7 mm and a perforated plate radius of 4.5 mm, were utilized. Five different operational modes were considered, while maintaining a blockage ratio of 0.88. The computational simulations were conducted using Fluent software, involving the solution of the three-dimensional Navier-Stokes equations and the k-ε turbulence model. Air served as the oxidizer, and methane was used as the fuel with an equivalence ratio of 0.65. The results indicate that modifying the length of the low-swirl burner blades exerts a substantial influence on the overall flow characteristics. As the blade length increases, the maximum velocity within the channel, corresponding to the four-bladed and eight-bladed burner, increased from 14 m/s to 20 m/s and from 19 m/s to 26 m/s, respectively. Additionally, concerning flame behavior, it was observed that in two instances with the four-blade burner, the flame failed to form a V-shape due to insufficient rotational motion. The findings revealed that in the specific geometric configuration of this research, a minimum rotational rate of 140 units/second was required to achieve a V-shaped flame. It is noteworthy that as the length of the rotating blades increased, the flame descended to a lower position, resulting in a maximum displacement of 4.7% and 7.8% for the four-bladed and eight-bladed burner, respectively