Investigation of an Inter-Compressor S-Duct Using the Lattice Boltzmann Method

This article presents the study of a subsonic inter-compressor S-duct. Numerical simulations are performed using large-eddy simulation (LES) based on a compressible hybrid thermal lattice Boltzmann method (LBM) implemented within the ProLB solver. Comparisons are made between the LES–LBM results, Reynolds-averaged Navier–Stokes (RANS) computations, and experimental measurements on a representative S-duct taken from the European project AIDA. Several cases with increasing complexity are addressed where the different rows surrounding the duct are gradually included in the computations. The effects of each row on the flow field development and loss levels are studied. The goal is to evaluate the ability of the LES–LBM to recover the aerodynamic behavior and the total pressure loss evolution within the duct. Results show that the LES–LBM retrieves the correct flow evolution inside the S-duct compared to the experiment and previous RANS results. The case where the upstream stator row or the low-pressure compressor stage is integrated shows an increase in total pressure loss, as previously observed in the literature, and a more developed flow field with complex flow features contributing to the loss generation. To further analyze the loss mechanism, an entropy-based approach is presented and highlights that most losses are generated close to the hub wall due to the migration of the upstream stator wakes.