Unsteady Simulations of a Fan/Outlet-Guide-Vane System. Part 1: Aerodynamics and Turbulence

摘要

The paper presents the aerodynamic ingredients of a two-part study devoted to creating and validating a high-fidelity CFD-based system for the reliable prediction of the performance and the noise associated with the Fan/Outlet Guide Vane (OGV) configuration typical of modern turbofan aero-engines (the aeroacoustic stage of the study is presented in Part 2). In terms of turbulence representation, the system offers two alternative approaches, namely, the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations and a zonal approach which treats the part of the flowfield located upstream of the fan by URANS and the remaining part (the inter-stage, OGV, and exhaust regions) by Improved Detached Eddy Simulation (IDDES) combined with a Volume Synthetic Turbulence Generator (VSTG) for triggering the scale-resolving capability of IDDES. In this paper we first outline details of the proposed methodology, including a general overview of the simulations, problem statements for a simplified (duct-only) and full (including the whole nacelle and external flow) configurations, and a description of the flow solver and numerics. After that, results are presented of the simulations aimed at demonstrating the capabilities of the methodology and its validation by means of comparison of the predicted mean and unsteady flow characteristics with experimental data for the baseline configuration of the NASA/GE Source Diagnostic Test (SDT) conducted at NASA Glenn Research Center in 1999. The numerical database accumulated in the course of the simulations is then used for investigation of noise-generation/propagation phenomena, for which results are presented in Part 2.