Experimental investigation on separation control by slot jet in highly loaded compressor cascade

Abstract

Separation control in compressor cascade is very significant for modern high efficiency compressor. This paper introduces a separation control approach using self-supplied jet in a highly loaded cascade. A novel arc slot is created into the cascade at the full span range, which connects the flow fields between the pressure and suction side. Because of the pressure difference, the slot enables to induce the jet flow into the suction side separation. Experiments are conducted to evaluate the separation control effects and preliminarily study the mechanism. The results show that the slot cascade acquires more ordered outflow by reducing the suction side separation and suppressing the complex vortices. Due to the great reduction of the separation, the total loss significantly decreases by 21.9% and the flow turning angle increases by 2.1 in average. According to the improvements of the cascade performance, the stable operating margin of the highly loaded cascade is greatly improved at least 3 in terms of the incidence angle.

Numerical and experimental investigations of flow separation control through a linear compressor cascade

“…In this study, for an incident angle of 6 °, the minimum pressure point, and the separation point were found to exist at 50% and 60% of the blade span; respectively. The inlet and outlet angles of the grooved slot were determined to provide an air jet with high outlet velocity to form a diverged-converged passage in accordance with the literature [25,30]. Slot width and height were selected to provide sufficient airflow to affect the separation zone and so can maximize the reduction in pressure loss no matter the tested incidence angles.…”

“…Ramzi et al [28] determined the appropriate slot location numerically and discovered it to be at mid distance between the minimum pressure point and the separation point. In this regard, the slot width should be designed proportional to the separation size; the larger the separation zone, the larger the slot width would be required [25]. The slot outflow angle is designed to produce an angle between the jet and mainstream flows, as studied by [29,30].…”

“…It was concluded that, for the slotted blade, the suppressed vortices in the flow separation zone associated with the re-energized low momentum flow reduce the loss coefficient by 17.7% for an incident angle of 6° with an insignificant reduction for zero-incident angle. Jiaguo et al [25] experimentally and numerically studied the effect of using a curved slot on highly loaded compressor cascade performance. They succeeded in getting a further reduction in the total losses by 21.9% associated with the ordered outflow that reduces the suction side separation.…”