Effects of pylon geometry on mixing enhancement in a scramjet pylon-cavity flameholder

Abstract

ABSTRACTNumerical investigation of the effect of pylon geometry within a pylon-cavity aided Supersonic Combustion Ramjet (SCRAMJET) combustor on mixing enhancement, flame-holding capability, fuel jet penetration and total pressure loss are conducted in the current study. RANS equations for compressed real gas are solved by coupled, implicit, second-order upwind solver. A two-equation SST model is used for turbulence modelling. Validation of the computational model is performed with the help of experimental data collected using surface pressure taps, Schlieren flow visualisation and particle image velocimetry (PIV). The study uses four distinct pylon geometry cases, which include the baseline geometry. Sonic injection of hydrogen fuel through a 1mm diameter hole at 2mm downstream of the pylon rear face along the axis of the test section floor is performed for every case. A crossflow of Mach number 2.2 at four bar absolute pressure and standard atmospheric temperature is maintained. A comparative study of mixing efficiency, total pressure loss, fuel jet penetration and fuel plume area fraction for the different cases evaluate the mixing performance. The simulations show that the Pylon 2 case gives a significant improvement in the performance parameters compared to the other geometries. It is observed that mixing efficiency and fuel jet penetration capability of the system are highly dependent on the streamwise vortex within the flameholder.