Abstract: First, the flow fields of two axisymmetric nozzles and a nozzle with four tabs are simulated using different turbulence models: the standard k-ε model, the realizable k-ε model, the renormalizationgroup (RNG) k-ε model, and the TamThies model. The results are compared with experimental data and it is found that the TamThies model provides the best results that exhibite the closest agreement with the experimental data. Then, the TamThies turbulence model is applied to simulate the flow fields of several nozzles with tabs whose orientation angles varied, and the results are also compared with a nozzle with no tab. The comparison shows that, due to the effect of the tabs, the length of the core zone decreases and the mixing of the shear layer is enhanced. As the orientation angle increases, the length of the core zones decreases first and then increases. A pair of counterrotating streamwise vortices with the same strength is generated downstreams each tab. As the orientation angle rises, the strength of streamwise vortices increases first and then decreases, while both the entrainment gain of the nozzle and the thrust loss coefficient decrease.

Key words: tab, orientation angle, turbulence models, vortex structure, mixing, thrust loss