Chemical Impulse Actuation for Aerodynamic Flow Control

Earlier investigations of active flow control have emphasized the utility of momentum-based fluidic actuation using 2- or 3-D air jets through the aerodynamic surface. Despite remarkable demonstrated control effectiveness of these approaches, their integration on realistic flight platforms has been hampered by the required air flow rates and actuation power (especially at high speeds). Therefore, the current investigations focus on the development of chemically-based impulsive actuation to produce high-speed momentary actuation jets while reducing or obviating the need for auxiliary air supply. To this end several propellant approaches are investigated including spark-ignited gaseous combustion, electrically-controlled fuel/oxidizer gels, and catalytically decomposed monopropellant liquids. The benchtop performance of these actuators is characterized in terms of the dynamic pressure that can be achieved within the reaction chambers, the achievable repetition rates and the structural features of the resulting jets. The control authority of these actuators is investigated in the separated flow over a 2-D wall-mounted NASA Hump in a small-scale transonic tunnel.