Numerical study of structural parameters on the performance of piccolo-tube muti-nozzles supersonic ejector in air-cooled passage

The enhanced performance of aircraft engines has intensified the challenge of improving cooling efficiency. In addressing the issue of inadequate cooling air in the idle and taking-off states, which adversely affects the working environment of the radiator within the air-cooled channel of aircraft engines, an enhanced cooling design method utilizing a piccolo-tube multi-nozzle supersonic ejector is investigated in this study. The structural parameters—including the number of nozzles, the arrangement of multiple nozzles, and the cross-sectional shape of the mixing chamber—are optimized to enhance entrainment performance. Changes to the structure of the ejector can impact its entrainment performance by altering the flow field. The findings indicate that when maintaining a constant total area for the nozzle throat, the entrainment performance of a double-row piccolo-tube ejector (DPE) surpasses that of a single-row piccolo-tube ejector (SPE), with an increase in entrainment ratio ranging from 16% to 20%. There exists an optimal number of nozzles that yield superior entrainment performance. Specifically, compared to the original SPE configuration featuring six nozzles, the optimized DPE demonstrates a 29% improvement in entrainment ratio under identical conditions. In addition, it is observed that variations in mixing chamber cross-section shape significantly impact entrainment performance by influencing vortex behavior near the wall.