Broadening the ignition boundary and enhancing combustion efficiency in a ramjet combustor with a plasma-type flameholder

The TBCC engine encounters challenges, including a notable decrease in thrust and inadequate acceleration during the mode transition phase. Leveraging plasma technology to expand the ignition boundary and enhance combustion stability is anticipated to address these issues effectively. Without altering the original structure of the flameholder, a plasma-type flameholder (PTF) capable of continuous actuation, disturbance, and possessing a large influence area was designed. Additionally, investigations into its electrical characteristics as well as its ignition and assisted combustion properties were conducted. The research reveals that as the total pressure (P∗) decreases, the output power of the PTF increases accordingly. Specifically, when P∗ is reduced from 97 kPa to 40 kPa, the output power increases by 25.4 %. The ignition and combustion experiments demonstrate that enabling the PTF effectively broadens the ignition boundary, reduces ignition delay time, enhances combustion stability, improves combustion efficiency, and optimizes the uniformity of the outlet temperature field. In the ignition experiment, as P∗ decreased from 97 kPa to 40 kPa, PTF actuation results in a maximal expansion of the ignition boundary by 35.6 % and a maximal reduction in ignition delay time by 36.0 %. Similarly, when the total temperature (T∗) increased from 320 K to 410 K, the ignition boundary is expanded by up to 51.2 %, and the ignition delay time is reduced by up to 56.7 %. In the combustion experiment, as P∗ decreases from 97 kPa to 40 kPa and the PTF is activated, the combustion efficiency increases by up to 8.5 %, while the overall temperature distribution factor (OTDF) and radial temperature distribution factor (RTDF) are reduced by up to 19.6 % and 15.4 %, respectively.