Active Combustion Instability Control During Scramjet Initiation Stage

摘要

This report was developed under SBIR contract for topic AF00-204. This SBIR Phase I project incorporated experimental and modeling efforts to develop an advanced active control strategy and a robust instrumentation/ actuation system for the suppression of combustion instability inside a scramjet during the initiation stage. The work carried out includes 1) development of micro-opto-mechanical (MOM) pressure sensors for the detection of instantaneous chamber pressure in a harsh environment, 2) development of aerated-liquid actuators capable of enhancing spray atomization and controlling droplet evaporation rate, 3) characterization of scramjet combustion instability, and 4) simulations of time-accurate combustion dynamics. It has been shown that the MOM pressure sensor exhibits a nearly linear response over pressure, with good sensitivity and dynamic response. The aerated-liquid actuator can achieve the desired mixing and, thus, heat release rate for the injected liquid as the liquid jet is aerated with a selected amount of gas. The low-frequency acoustic signatures inside a liquid-fueled scramjet combustor were shown to be manageable. Results from time-accurate calculations have closely mimicked the experimental conditions and operating procedure. This approach to the detection and control of combustion dynamics was proven to be feasible and can be applied to scramjets, as well as other liquid fueled propulsion systems.