Numerical Investigation of Asymmetric Lobe Structure on Aerodynamic Performance of a Lobed S-Shaped Nozzle

摘要

The effect of asymmetric lobed mixer on aerodynamic performances of a lobed S-shaped nozzle was studied by using the validated numerical method. The three-dimensional steady flow fields within the lobed S-shaped nozzle were obtained and the turbulent flows were simulated by solving the Reynolds-averaged Navier-Stokes equations with the realizable k-e turbulence model. Both the mixed flow field and the aerodynamic performances of the lobed S-shaped nozzle were discussed. The flow field downstream of the lobed mixer was significantly influenced by the S-shape of the exhaust nozzle leading to the supersonic flow occurred in the outlet region although the nozzle studied in this paper is a converging nozzle. The baseline case is shown to be the case with the lowest magnitude of total pressure recovery coefficient in all the studied cross sections. Besides, the discrepancies of total pressure recovery coefficient between the baseline case and the asymmetric cases are gradually enhanced as a response to the extended mixing distance for the flow field upstream of the X/D=0.6 cross section. While the discrepancies are observed to be nearly constant for the flow field following the X/D=0.6 cross section due to the dissipations of large scale stream-wise vortexes. The asymmetric case 3 outperforms all the studied cases in the perspective of overall aerodynamic performances in which when comparing with the baseline case the maximum normalized wall temperature and the total pressure recovery coefficient has decreased 14.67% and increased 0.04%, respectively.