Improved flammability for hydrogen fuelled scramjets with preinjection catalytic radical farming

摘要

Scramjet engine flight envelopes are limited to high Mach numbers due to autoignition limitations. Additionally, combustor efficiency is impacted by ignition delay times, as it directly influences the necessary combustor length. Numerical simulations using Cantera and a reduced GRI 3.0 mechanism suggest improvement of both autoignition and ignition delay times by preseeding the flow with radicals. As a nonintrusive way to produce the necessary radicals, a catalytic approach is chosen. Experimental investigations suggest a small but constant decrease in autoignition. The impact on ignition delay times is significant, but additional challenges arise due to changing flow properties with thermally driven boundary layer growth. Both improvements lag behind the numerically suggested potential, as water vapour produced in the catalytic reaction has an inhibiting effect.