Airwake Simulation of Modified TTCP/SFS Ship

摘要

Recent work on airwake simulation based on the steady-state solution to Navier-Stokes equations provides reasonably accurate flow field results that are useful to supplement experimental measurements which otherwise would be more costly and time-consuming. Work on airwake of a special configuration, the Simplified Frigate Shape (SFS), as defined by The Technical Co-operative Program (TTCP) panel, is aimed at validating computational fluid dynamics (CFD) codes. Simulated airwake results based on steady-state solution have been determined by Long et al and Reddy et al. Unfortunately, the SFS configuration has a flat nose that can cause numerical difficulties and lead to discrepancies between the results of CFD simulations and wind tunnel tests. This paper discusses the drawbacks of the SFS ship, proposes a modification to the original configuration, and presents simulated airwake results over the modified ship. The SFS ship configuration is modified by adding a rounded bow section at the front end to avoid complete separation along the side walls. Airwake of the modified configuration, subject to atmospheric wind of 70 feet per second at wind angles of zero and 40 degrees, is simulated by using a multi-zone, thin- layer Navier-Stokes method. The resulting flow contains regions of massive separation along with free vortices, but there is no observed separation along the hull surface. Major flow features, including viscous-vortex interactions, are captured. Large leading-edge separation coupled with leading-edge vortices at the front end of the round bow are detected. The flow then re-attaches over the forward deck. Calculated velocity data in the flight deck region will be made available to TTCP member activities upon request by e-mailing to the author. (20 figures, 17 refs.).