Combustion characteristics of supersonic strut-cavity combustor under plasma jet-assisted combustion

Plasma jet has been widely used in supersonic combustor as an effective ignition and combustion assisted method, but currently it is mostly combined with the traditional wall fuel injection method, while the application combined with the central fuel injection method is less. In order to expand the combustion range, the plasma jet was introduced into a strut-cavity combustor with an alternating-wedge. The effects of total pressure of strut fuel injection, total pressure of cavity fuel injection, total pressure of plasma jet injection and plasma jet media on the combustion characteristics were analyzed in supersonic flow by numerical calculations in a three-dimensional domain. The combustion field structure, wall pressure distribution, combustion efficiency and distribution of H2O at the exit of the combustor with different injection conditions were analyzed. The results show that the combustion efficiency decreases with the increase of the strut fuel injection total pressure. However, the combustion area downstream increases when the total pressure of the strut fuel injection increases within the proper range. The combustion range is expanded and the combustion efficiency is improved when the cavity fuel injection total pressure is increased within the range of 0.5-2.0 MPa, but a sharp drop in combustion efficiency can be found due to limited fuel mixing when the total injection pressure of the cavity fuel is excessively increased. With the increased total injection pressure of the plasma jet, the height of the cavity shear layer is raised and the equivalence ratio of the gas mixture in the cavity is improved. When the total pressure of the plasma jet is 1.25 MPa, the combustion efficiency reaches a maximum of 82.1%. The combustion-assisted effect of different plasma jet media is significantly different. When the medium of the plasma jet is O2, the combustion-assisted effect on the combustor is most significant.

Automated summary

The study analyzed the combustion characteristics under different injection conditions, revealing that an increase in total pressure of strut fuel injection leads to a decrease in combustion efficiency. However, increasing the total pressure of strut fuel injection within a proper range can expand the combustion area downstream. Increasing the total pressure of cavity fuel injection within the range of 0.5-2.0 MPa expands the combustion range and improves combustion efficiency, but excessive total injection pressure of cavity fuel can result in a sharp drop in efficiency. Increasing the total injection pressure of the plasma jet raises the height of the cavity shear layer and improves the equivalence ratio of the gas mixture in the cavity, with a maximum combustion efficiency of 82.1% achieved at a total pressure of 1.25 MPa. The combustion-assisted effect of different plasma jet media varies significantly, with O2 having the most significant effect on the combustor.