出口宽高比对双涵道S弯喷管流动特性的影响

In order to clarify the influence mechanism of aspect ratio on flow characteristic of serpentine nozzle on the basis of real exhaust mixer configuration in the turbofan engine, the internal flow and external jet characteristic of double serpentine nozzle under the conditions of different aspect ratios had been simulated numerically. Results are obtained as follows: The flow features around exhaust mixer were changed hardly on the conditions of different aspect ratios. The stretching of streamwise vortices was more serious at the transversal inflections meanwhile the vorticities decreased at the longitudinal inflections as aspect ratio increased constantly. The vorticities loss and mixing loss were enlarged in the former directly while it diminished in the later. The shear stress at the wall surface of two inflections and linear section regions decreased gradually with increment of aspect ratio, where the friction loss and local loss were weakened effectively. However, the curved extents of limiting streamlines on the upper and lower wall surface were strengthened apparently which expanded toward outside firstly and then contracted toward innerside along the flow direction. Correspondingly, the aforementioned friction loss in the serpentine nozzle were enlarged remarkably. The axial velocity of plume potential core near nozzle exit increased gradually as the aspect ratio rose while its axial length was shortened dramatically. As a result of coupling effects between exhaust mixer and different nozzle geometric configurations, there appeared the opposite variety trends of multiple flow losses. Generally, the aerodynamic performance of double serpentine nozzle was almost unchanged.