Numerical Simulation On The Flow Characteristics Of Trapped Vortex Combustor With Guide Vane And Bluff Body

The trapped vortex combustor(TVC) has gained many advantages relative to the conventional combustor. With the characteristics like simple construction, light weight, unique way to flame stabilization, strong ability of reigniting and low pollutant emission, TVC has been paid attention widely. A new aerodynamic structure was put forward and numerical simulation of turbulent flow about the TVC was carried out.In order to make sure the superiority of the combustor with bluff body, two kinds of TVC of which one with bluff body and the other without were contrastive analysis by the steady and unsteady simulation. The results show that under the unsteady simulation, the double vortex of the flow field in the cavity changes according to the process like shaping initially—breaking—regrouping—tending to be stable gradually. The value and distribution area of the turbulence energy rise and the heat and mass transfer of the combustor increases with the set of the bluff body. The total pressure loss of the combustor without bluff body is 1.8% compared to the combustor with bluff body is 3.3%, and the combustion efficiency of the combustor without bluff body is 73.58% while the combustor with bluff body is 99.59% under the steady simulation. The recirculation zone behind bluff body can increase the combustion efficiency greatly and improve the temperature distribution of the exit.In order to optimize the structure of trapped-vortex combustor with guide vane and bluff body, numerical simulation of combustion turbulence flow was performed by changing size and location of guide vanes and bluff bodies. The results show that the longer the length of blunt body and the distance between guide vane and imported wall is, the higher the combustion efficiency gets. The highest combustion efficiency is up to 99.99%. There exists a relatively optimal structure of the bluff body and guide vane under comprehensive consideration. In this configuration, the total pressure loss is 6.66% and the combustion efficiency is 99.79%.In order to study the flow characteristics about the optimal structure of TVC, numerical simulation of combustion turbulence flow was conducted by changing different influence factors. The results show that high inlet temperature and low inlet velocity can reduce the total pressure loss, while the change of equivalence ratio has little impact on total pressure loss. Combustor’s performance under lean oil condition is better than rich oil condition, and when the equivalence ratio is less than 1, the combustion efficiency will reach over 99.8%. The distributaries’ velocity perpendicular to the main flow direction which caused by streamline bluff body is low, and the same with the total pressure loss. In all cases, the total pressure loss in circular bluff body is the lowest, and both the combustion efficiency and total pressure loss of the rectangle bluff body are the highest. It should be considered comprehensively when choosing the shape of the bluff body in practice.