Performance of a novel mixed-flow trapped vortex combustor for turboshaft engine

Abstract

This paper describes a novel compact combustor that utilizes trapped vortex in a single cavity to provide flame stability. This novel combustor combines the characteristics of the reverse-flow combustor and the straight-through combustor, named mixed-flow trapped vortex combustor (TVC). All the liquid RP-3 kerosene is injected directly into the cavity. Combustion performances such as pressure drop, lean blowout (LBO) limits, temperature profiles, combustion efficiency and emissions were examined experimentally using a sector test rig under ambient pressure with a temperature of 300, 433 and 500 K, respectively. Experiment results showed that the pressure loss varied as the square of the inlet velocity and not exceeded 5%. The overall fuel to air ratio (FAR) of LBO limits was less than 0.0043, and the lowest LBO limits was achieved at the lowest inlet air velocity and highest temperature. The effect of cavity equivalent ratio on the temperature profiles was greater than the inlet air velocity. There was an optimal cavity equivalent ratio for a given inlet air velocity to make the temperature profile closer to the desired temperature profile. Combustion efficiency was above 96% under all operating conditions. The lowest combustion efficiency occurred at the highest inlet velocity. An increase in the inlet velocity results in an increase of the concentration of unburned hydrocarbons (UHC) and carbon monoxide (CO). The emission index of oxides of nitrogen (EINOx) was less than 2.1 under all operating conditions.