Comparative study on the performance of turbulence models in flow separation of large expansion ratio nozzle

Abstract The asymmetry of flow separation inside the nozzle with large expansion ratio is the main factor for the generation of side-load in the engine, so the accurate prediction of the flow separation is of great significance. The turbulence model is the key to the prediction, but in different scenarios, the performance of the turbulence model can introduce huge uncertainties. In this paper, a typical thrust-optimized nozzle (VOLVO-S1) is simulated and analyzed for three widely used turbulence models: SST k - ω 、 RNG k - ε and Spalart-Allmaras model. The results show that all these models can effectively predict the mode of shock separation phenomenon. The comprehensive performance of SST k - ω is the best; The Spalart-Allmaras model has better prediction performance under low pressure ratio, and the RNG k - ε model has better prediction effect under high pressure ratio.