Analysis of a Turbulent Propeller Inflow

Abstract

The unsteady turbulent inflow into a swirl-inducing stator upstream of propeller (SISUP) propeller is presented. The upstream stators and hull boundary layer generate a complex, three-dimensional inflow that was measured using x-wire anemometry. High resolution measurements consisting of 12 locations in the radial direction and 600 in the circumferential direction yielded mean velocity and rms turbulent quantities for a total of 7200 points. The axial, radial, and circumferential velocity fields were thus measured. This enabled the induced velocity due to the stator wakes, the induced velocity due to the propeller, and the turbulent hull boundary layer to be characterized. To assist in decoupling the effects on the velocity field due to the stator and propeller, a potential flow computation of the swirl component was used. Spectra and autocorrelation analysis of the inflow velocity field were used to estimate the integral length scale and lend further insight into the turbulent flow structure. These data can be used to validate computational fluid dynamics codes and assist in developing of turbulent inflow models.