Experimental and numerical investigation of a propeller with three-dimensional inflow

Abstract

The goal is to study the three-dimensional (3-D) flow produced by a propeller operating in a 3-D approach flow representative of pusher-prop arrangements on aircraft or underwater vehicles. The research involves both numerical predictions and wind-tunnel experiments. The specific nonuniform inflow studied is generated by a varying mesh screen disk of one large-diameter mesh, one smaller-diameter mesh, and a 30-deg mesh wedge aligned with the tip of the wedge and the centers of the two circular screens matching. This inflow is similar to the wake behind a slender axisymmetric body with a slender planar appendage. The propeller has three blades, and is self-propell ed with respect to the drag of the screen disk. The testing is divided into two main parts. The first deals with propeller performance and the condition needed to reach a self-propelled mode. The second part is the measurement of the mean and turbulent flow downstream of the propeller for two axial locations, x/D - 0.025 and 0.5. The computational work is part of a step-by-step approach to development of a method for analysis of propeller flowfields with three-dimensional inflows of increasing complexity. The fully elliptic, 3-D, Reynolds-averaged, steady-state, primitive-variables Navier-Stokes equations are solved by a Penalty Finite-Element Method. Turbulence modeling is through the integrated turbulence-kinetic-energy (TKE) model. The length scale is algebraically related to the axial velocity profiles. The propeller is modeled as an actuator disk. The mesh disk is modeled as a distribution of axial-body forces, which are related to the local drag. Generally, the agreement achieved between predictions and experiment is considered excellent for a 3-D, turbulent flow of this complexity.