Unsteady characteristics of jet combustion in a supersonic combustor with a micro-vortex generator

To clarify the effect of the micro-vortex generator on the unsteady characteristics of jet combustion, a set of experiments had been carried out in a cavity-based supersonic combustor. Based on the advanced combustion diagnosis techniques, the ignition process, initial cavity-stabilized flame and dynamic flame development at the initial equivalence ratio of 0.20 are revealed in detail. Although the ignition processes are identical, the time for the flame propagation process in the cavity can be shortened when an MVG (micro-vortex generator) is located properly upstream of the injection. The initial flame cannot be stabilized in the combustor if the MVG is too close to the injection. After achieving initial stable combustion, the chemical reactions in the flame front are more vigorous and the shear layer can be lifted a little higher in the experiment with an MVG. At the same dynamic fuel adjustment method, the flame can be stabilized in the combustor without an MVG while the flame is blown out with an MVG. Based on numerous experimental results, it is found that the MVG dwindles the adjustment range of the dynamic injection, which makes against the stability of the flame when the engine decreases the thrust.

Effects of segmented layer suction and micro-vortex generator on a high-load compressor cascade performance

The axial location of full-span boundary layer suction is studied to explore the influences of suction slot on the cascade performance. At the design condition, the slot with 50% axial location shows a superior capability to reduce the total pressure loss. At the near stall condition, the more upstream of the suction slot is moved, the more total pressure loss is reduced, and the suction slot with a location of 0.7 axial chord length cannot effectively reduces the total pressure loss in all conditions. Moreover, a rearranged segmented suction slot according to the distribution characteristics of the flow reversal region is developed and compared with full-span boundary layer suction. The segmented suction slot shows significant advantages in delaying the stall occurrence, and the stall point is delayed from 7.9° to 10.0° compared with the baseline. According to a quantitative analysis method selected to measure the performances of flow control technologies, the wake loss is significantly reduced by the segmented suction slot. Finally, a set of micro-vortex generator is introduced in the cascade with a segmented suction slot, and the conclusion indicates that the portion near the end-wall is very effective to reduce the flow loss.