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

Abstract

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 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 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.