Numerical investigation of mixing length on performance of lobed forced mixer nozzles

Abstract

Geometric models of a lobed mixer nozzle with variation of mixing length are created and corresponding flow fields are simulated using a steady Reynolds Averaged Navier-Stokes (RANS) equation with realizable k-ε turbulence model. The numerical simulation results show that the mixing length of the nozzle has a relatively great influence on the development of streamwise vortices and the effective range for streamwise vortices to intensify mixing is about 0.5D distance from the lobe trailing edge. The change of mixing length has little effect on the thermal mixing efficiency. As for the total pressure recovery coefficient, the shorter the mixing length, the sharper the total pressure recovery coefficient curve. On the nozzle exit section, the thermal mixing efficiency increases at first and then slightly declines, and the total pressure recovery efficiency changes little as the mixing length increases. In addition, the thrust coefficient has some small relationship with the mixing length. The thrust coefficient increases in waves as the mixing length increases and the difference between the maximum and the minimum values is slightly less than 1% when the mixing length increases from 0.4D to D.

Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

“…Except for the investigations above, Liu and Xie have also conducted a series of meaningful studies concerning the effect of detailed lobe geometrical parameters on the aerodynamic performance of the life-sized lobed nozzle, i.e. lobe number [11], lobe width [12] and forced mixing length [13].…”