Numerical Investigation of Performance of the Air Tab in the Turbofan Nozzle

The air tab is a new technique with better effects on mixing but minimum penalty on thrust. The present numerical investigation aims to study the mixing effect in the turbofan nozzle. Meanwhile, the parametric studies of the air-tab flow rate omega and the tube inner diameter of the air tab d are also carried out. The thermal mixing efficiency eta(T), the total pressure recovery coefficient sigma(air) (tab), and the thrust coefficient C-f are compared to find out the quantitative differences among the models researched. The results reveal that the air-tab technique would increase the thrust a little further rather than create a great penalty on thrust by the jet itself. The thermal mixing efficiency increases greatly from 0.1756 to 0.3425, whereas the high-temperature region (where the temperature is higher than 650 K) is reduced from 29.2 to 5.2% and the thrust coefficient is nearly unchanged, with the air-tab flow rate only about 0.58%. The results also reveal that the depth of penetration cannot determine the thermal mixing efficiency. In addition, there is little difference for total pressure loss among the air-tabbed models at the lobe exit.