Turbulence control and thrust augmentation in a ramjet combustor using transverse slot jets

The high velocity flow in a ramjet requires a flame stabilization scheme to prevent blowout. Normally, this was done using a rapid cross-sectional area change like a backward facing step (BFS). From the sudden expansion, a recirculation zone forms that acts as a flame anchor. Although the sudden expansion facilitates combustion stabilization, a drag penalty is incurred. For the present text, flame stabilization was attempted using a confined transverse slot jet that formed a recirculation zone. Flow control was explored by changing the mass and momentum flux of the transverse slot jet under nonreacting conditions. It was found that momentum ratio (MR) was the dominant scaling parameter for the lengthscales of the recirculation zone. For a transverse slot jet that does not extend the full span of the channel (wslot/W<1) the flow was found to be highly three dimensional with secondary rotation and counter rotating vortex pairs (CVP). A secondary jet, downstream of the first and within the recirculation zone was also installed and used to explore another means of flow control. Dominant turbulent frequencies at various operation conditions were also explored. Measurement of the flow was done using digital particle image velocimetry (DPIV). It was found that the transverse slot jet has potential to act as a flame anchor.