Ignition and Combustion Performance of Scramjet Combustors with Fuel Injection Struts

Ignition and combustion performance of a scramjet combustor with a fuel injection strut was experimentally investigated with Mach 2.5 vitiated air. Five strut models with different leading-edge geometry were tested without fuel injection to select the less flow-disturbing configuration. The nonreacting flowfields were also investigated by computation with a two-dimensional Navier-Stokes code. Using the selected strut, combustion and ignition tests were conducted. A pitot pressure and gas composition survey was carried out to deduce mixing and combustion efficiencies. It was found that mixing and combustion with a less flow-disturbing strut was considerably worse than those with a more flow-disturbing strut. Autoignition and forced ignition with plasma torches were tested for hydrogen. Ignition characteristics of parallel and perpendicular injection were quite different. The plasma igniters could successfully ignite both parallel and perpendicular fuel jets without a noticeable time delay between both sides of the strut.