Numerical Predictions of Scarfing on Performance of S-Shaped Nozzle with Asymmetric Lobe

摘要

Numerical predictions of a lobed jet mixing flow within an S-shaped nozzle were conducted with respect to the influence of lobe scarfing on performance of the lobed S-shaped nozzle. The simulation results presented in this paper were all obtained by solving compressible steady three-dimensional Reynolds-averaged Navier-Stokes equations with a realizable k-e turbulence model. The effect of scarfing optimization was mainly addressed by both the flowfield downstream of the lobed mixer and the interested variables characterizing the performance of the lobed S-shaped nozzle. Due to the studied S-shaped nozzle, a sharp decrease of total pressure recovery coefficient, as well as a reduced thermal mixing efficiency, within the flowfield close to the outlet is shown. The model with a bigger scarfing angle is suggested to induce the forced mixing process ahead of schedule, but with less mixing strength as compared with the baseline model. However, the model with a more aggressive scarfing angle is shown to be the case with both a decreased thermal mixing efficiency and an augmented total pressure recovery coefficient within the flowfield downstream of the L/D = 0.2 cross section, except the 20 deg scarfing model. Both the thrust coefficient and thrust mixing efficiency are all found to decrease as a result of the tested model with a bigger scarfing angle.