Marine Propeller Blade Tip Flows.

摘要

A numerical lifting surface method is developed for the prediction of the steady, non-cavitating flow around the tips of marine propeller blades. An inviscid flow model is employed together with a local viscous analysis of the leading edge flow behavior, and the major effects of vorticity shed from swept leading edges are included. The usual propeller analysis problem is solved using a vortex lattice approach, which includes an efficient method for calculating the correct geometry of the trailing vortex wake. The attached flow analysis is broken down into 'global' and 'local' problems to yield high resolution in the tip region without an undue penalty in computation time. A semi-empirical viscous analysis, bases on airfoil and swept wing data, is used to determine the amount of vorticity shed into the fluid due to flow separation at the blade leading edge. A first-order representation of the leading edge vortex sheet is employed to solve the resulting boundary value problem. Comparisons between computed results and available experimental data are generally quite good. The theory qualitatively explains the influence of skew on leading edge sheet cavitation inception, and also predicts a substantial Reynolds number effect. Data at higher Reynolds numbers are required to confirm the scale effects predicted by the current theory. (Author)