Pylon-Aided Fuel Injection into Supersonic Flow

Abstract

A thin wedge-shaped blade, sometimes known as pylon, was used to enhance transverse fuel mixing in Mach 2 airflow. Supersonic mixing experiments were conducted using 45° and 90° fuel injections from the wall in the immediate wake of the pylon blade, and the results were compared with a baseline case using 90° transverse fuel injection without any pylon assistance. All the injectors had a same-size diameter, and the injector diameter matched the maximum blade thickness at the pylon base. For both qualitative and quantitative comparison, wall-pressure measurements, planar Mie-scattering of smokeseeded fuel streams, and instantaneous and time-averaged schlieren visualization were employed. Fuel penetration height was measured as a function of axial distance from the schlieren images, while flow losses associated with pylon and jet-induced shocks were assessed from the wall pressure measurements. Also, the wake flow extending downstream from the pylon base was characterized by planar Mie-scattering images. Substantial improvement in mixing performance was observed with the use of pylon as the fuel penetration height was increased by 100~120% and the flow losses associated with jetinduced shock were reduced by 13~30%. The 90° injection achieved greater fuel penetration heights, while the 45° injection incurred greater savings in flow losses. The results open up the possibility of further increasing the performance by optimizing the fuel injection angle behind the pylon.