Numerical Investigation of Lobe Length on Performance of Lobed Forced Mixer Nozzles

摘要

Geometric models of lobed mixer nozzle with variation of lobe length are created and corresponding flow fields are simulated using a steady Reynolds Averaged Navier-Stokes equation with Realizable k-ε turbulence model. The numerical simulation results show that the lobe length has great influence on the streamwise vortices at the lobed mixer exit. Therefore, at beginning of mixing, change of lobe length has great influence on the thermal mixing efficiency and the total pressure recovery coefficient. The thermal mixing efficiency increases sharply at the beginning, then gradually, approaches some constants along the flow axial direction, while it is the same trend for the total pressure recovery coefficient with the reverse changing trend. At the mixing nozzle exit cross-section, the thermal mixing efficiency rises and the total pressure recovery efficient reduces as lobe length increases. In addition, the thrust coefficient has change little, when the lobe length increases from 0.12 D to 0.24 D.