Numerical Studies Of Combustion And Flow Characteristics In A Trapped Vortex Combustor

Trapped vortex combustor(TVC)has the advantages of simple structure,light weight,enhanced combustion stabilization capacity,high combustion efficiency,low NOx emission and low total pressure loss.In this work,the combustion performances and flow dynamics of the first generation trapped vortex combustor was studied and analyzed by numerical simulation under different cavity inlet parameters?different operating conditions with methane fuel and additional fuel injection from the front blunt body.1.In order to investigate the influence of inlet parameters on the flow characteristics and combustion performances of the TVC,three-dimensional numerical simulation method was used as the total volume of gas injection of cavity remains unchanged.The inlet parameters include:(1)inlet injection angles of after blunt body,(2)injection apertures of fuel and air,(3)main inlet velocities.The numerical results show that the injection angle and direction of after blunt body have great influence on the structure of the vortex in cavity.When the injection angle is negative,the vortex intensity and combustion performance in the cavity is strengthened.However,as the injection angle is changed to be positive,a multi-vortex structure is generated.In addition,the decrease of fuel and air injection aperture can increase the combustion performance in the cavity.Finally,increasing the main flow inlet velocity is shown to increase intensity and stability of the vortex in the cavity.2.In order to study the combustion performance of the TVC under gas turbine combustor inlet conditions and using methane fuel,the combustion performance and pollutant emission performance of the combustor under different operating conditions were analyzed by using three-dimensional numerical method.The results show that combustor has high combustion efficiency and low total pressure loss under different operating conditions with methane fuel.In addition,the mainstream equivalent ratio increase the Emission Index of Nitrogen Oxides;when the mainstream equivalent ratio of the combustion chamber is fixed,main inlet velocity and cavity equivalent have less influence on EINOx of the combustor.3.In order to study the combustion performance of trapped vortex combustor under the condition of adding fuel injection from the front blunt body,three-dimensional numerical simulation method was used to simulate and analysis the combustion efficiency and the combustion performance of the TVC under the condition of adding front bluff body fuel injection and without the front bluff body fuel injection.The numerical simulation results show that the front bluff body injection coefficient in the range of 0.2-0.7 optimized outlet temperature distribution,improved the combustion efficiency of the combustion chamber under the same axial length and had a little influence on total pressure loss of the TVC.In addition,the results also revealed that variation over a certain range of the pore size of the fuel injection hole at the top of front bluff body has a little influence on combustion efficiency,outlet temperature distribution and total pressure loss of the TVC.