Combustion Powered Actuators for Separation Control (Invited)

An overview is presented of research involving the development and application of combustion powered actuation (COMPACT) for active control of separated flows. This actuation approach produces high-speed, pulsed actuation jets through the ignition of a mixture of gaseous fuel and air within a cubic-centimeter-scale combustion chamber. The basic characterization of the actuator including several geometric and chemical factors that affect the actuator performance is described. Dynamic pressure measurements and PIV show how these factors alter the dynamic pressure pulse within the combustor and the ensuing actuation jet. Environmental testing performed on the actuator is discussed for several harsh environmental conditions with sample results presented for rain exposure. Aerodynamic applications of COMPACT to mitigate both 2-D and 3-D separated flows are also described for airfoils and fuselage integration into a generic rotorcraft body. Flow field measurements show that reattachment of large-scale flow separation is accomplished for each of these applications with the reattachment taking place over a much larger time scale than that of the actuation pulse or the convective time over the surface, resulting in enhanced transitory aerodynamic performance.