Effect of aspect ratio and swirl angle on temperature distribution of double serpentine nozzle for turbofan

The effects of the aspect ratio and the swirl angle on the temperature distributions of the internal flow and external jet fields of the double serpentine nozzle with real lobed mixer configuration were numerically investigated.The results indicated that，under the action of the bending configuration with the circular-to-rectangular transition，the streamwise vortices induced by the lobed mixer and the tail cone entrained the core flow to impact the nozzle wall，and the “hot streak” was formed at the wall surface of the second S passage and the linear section.Under the constraint of the criterion of completely shielding high temperature components，the tempera-ture of the “hot streak” on the nozzle wall first increased and then decreased as the aspect ratio raised gradually.The value of the temperature peak of the “hot streak” was up to maximum when the aspect ratio was 5.It rose by 1.3% compared with that in the benchmark nozzle model.The plume core region downstream the nozzle exit was shortened effectively with the increment of the aspect ratio.The temperature of the “hot streak” on the nozzle lower wall first decreased and then increased as the swirl angle raised sustainedly.The value of the temperature peak of the “hot streak” was up to minimum when the swirl angle was 10°.It dropped by 15.9% compared with that under the condition of 0° swirl angle.The lateral width of the plume core region downstream the nozzle exit was enlarged notably while its axial length was shortened effectively with the increment of the swirl angle.