Characterization of the Internal Flow Dynamics of Combustion Powered Actuators

The internal flow properties of small-scale combustion-powered fluidic actuator for flow control applications are characterized over a range of combustion chamber geometries and gas mixture flow conditions. Momentary (pulsed) actuation jets are produced by the ignition of a mixture of gaseous fuel and oxidizer within a cubic-centimeter-scale chamber. The combustion process yields a high pressure burst and the ejection of a high-speed exhaust jet. Modular chambers were constructed specifically to allow optical access to the chamber for phase-locked Particle Image Velocimetry (PIV) measurements over both the baseline and combusting flows as well as dynamic pressure measurements. It was observed that for low flow inlet velocities (in both remixed and non-premixed actuator configurations) an essentially laminar flame propagation process is observed. At increased mean inlet flow velocities for the non-premixed geometry, a transition quickly occurs to produce significant wrinkling of the flame front and an apparently irregular flame propagation process through the chamber. Information obtained during this and future similar studies will be used to create actuator designs with improved refill and combustion processes.

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