LES of Combustion Flow Field in a Practical Aeroengine Combustor with Two-Stage Counter-Rotating Swirler

Abstract

To improve knowledge of the reacting flow in real aeroengines, large eddy simulation (LES) with dynamic Smagorinsky subgrid model is used to explore the complex unsteady flowfield in a single burner of a typical aeroengine combustor with radial two-stage counter-rotating swirler. Three combustion models namely fast chemistry model (FC), flamelet model (FLM) and progress-variable model (FPV) are applied. The complex geometric configuration including all film cooling holes is fully simulated without any conventional simplification in order to essentially reduce the modeling errors. Based on the non-reacting flowfield which has been advanced to the statistically stationary state in early work, unsteady process of fuel injection is first simulated without reaction. It cost about 2.6ms for adequate fuel reaching the real ignition location, then pseudo ignition is numerically conducted using FPV model in the given sphere region with a radius of 3mm. The process that initial flame propagates along the isoline of stoichiometric mixture and fills the whole chamber under the effect of transverse flow is simulated. It costs about 6~7ms for the flame arriving at the outlet. Compared to coherent anti-Stokes Raman scattering (CARS) measurement of mean temperature on central profile, mean error of LES-FPV, RANS-FPV, LES-FLM and RANS-FLM in the reference are 3.47%, 4.17%, 7.76% and 11.22% respectively, indicating that LES improves the accuracy and FPV performs better than FLM. Due to the severe hot spot at the outlet, RANS-FPV gives the poorest outlet temperature distribution factor (OTDF) and maximum radial temperature distribution factor (RTDF) as 0.593 and 0.313 respectively. Corresponding values predicted by LES-FPV are 0.284 and 0.193, presenting the best uniformity among all cases.