Computation of Viscous Flow Around Propeller-Body Configurations: Iowa Axisymmetric Body

Abstract

Further validation of a viscous-flow method for predicting propeller-hull interaction is provided through detailed comparisons with recent experimental data for the practical configuration of the Iowa axisymmetric body. Modifications are made to the k-ε turbulence model and wall functions for axisymmetric bodies. Close agreement is demonstrated between the calculations and the data, which supports the conclusion that the present procedures can accurately simulate the steady part of the combined propeller-hull flow field. However, the present extensive comparisons also point out the critical role of turbulence modeling and detailed numerical treatments. Also, comparisons are made with Huang's inviscid-flow method. Although both methods show similar trends, there are some important differences; for example, Huang's method predicts reduced propeller loading and larger axial velocities in the propeller plane near the body surface and propeller tip. Near the propeller tip, the present method exhibits a velocity defect region, which is absent in Huang's method. In consideration of the greater rigor of the present method, such differences imply that viscous effects play an important role in propeller-hull interaction even for the relatively simple case of an axisymmetric body and should be accounted for in the design procedures of wake-adapated propellers. However, part of the differences may be due to some of the present detailed numerical treatments, which indicate the need for continued refinement of comprehensive methods, such as the present one, and more detailed experimental information for validation purposes.