Effect of rear blunt body structure and inlet conditions on the flow and combustion characteristics of an advanced vortex combustor for a gas turbine

The rear blunt body plays a crucial role in the total performance of an advanced vortex combustor. This paper presents a numerical simulation study on the flow and combustion characteristics of an advanced vortex combustor fueled by liquid aviation kerosene under atmospheric pressure conditions, with inlet velocities of 0-100 m/s and inlet temperatures of 300-800 K. Different structural and aerodynamic parameters, including cavity length, rear blunt body height, rear blunt body width and inlet conditions are studied to determine the variation trends of the velocity field, total pressure recovery coefficient, fuel concentration field, combustion efficiency, outlet temperature distribution and pollutant emissions. The results indicate that the presence of the rear blunt body facilitates the formation of a dual vortex structure within the cavity, leading to an increased total pressure recovery coefficient, an improved fuel concentration distribution, an enhanced combustion efficiency, and a more uniform outlet temperature distribution. At an inlet velocity of 100 m/s, the total pressure recovery coefficient increases from 97.01 % to 97.29 %. However, as the cavity length, the rear blunt body height and width increase, the total pressure recovery coefficient and the CO emission increases, and the combustion efficiency, outlet temperature distribution and NO emission decrease to different degrees. In addition, an increase in inlet temperature enhances the fuel concentration distribution, leading to improved combustion efficiency, better outlet temperature distribution, and an increase in NO emission. Additionally, it results in a reduction in CO emission. As the inlet temperature increases from 500 K to 800 K, the combustion efficiency increases from 86.57% to 92.81 %, representing a growth rate of 7.21 %. In summary, when the cavity length is 24 mm, the rear blunt body height is 24 mm, the rear blunt body width is 5 mm, and the inlet temperature is 800 K, the overall combustion performance of the advanced vortex combustor is optimal, which is conducive to providing an important theoretical basis for the design and optimization of advanced vortex combustors.