Measurements of Loading and Tip Vortex Due to High-Reynolds Number Flow Over a Rigid Lifting Surface

Abstract

An experimental study of high-Reynolds number flow over a rigid hydrofoil (David Taylor model basin (DTMB) modified NACA66-009, rectangular planform, aspect ratio (AR = 4, square tip) is presented. The measurements were performed in the Garfield Thomas Water Tunnel at Applied Research Laboratory (ARL) Penn State. Load measurements were performed at ReC = 1.5 × 106 and 2.4 × 106, for angles of attack between −8 deg and +8 deg. Measurements of three components of velocity were performed using stereo particle image velocimetry (SPIV) on a cross-flow plane to resolve the tip vortex flow 0.42 chord lengths downstream of the trailing edge, for four angles of attack ranging from 0.5 deg to 3.5 deg. Nondimensional tip vortex circulation varied weakly with angle of attack. Vortex location in the plane of measurement, relative to the trailing edge, was unchanged for the ranges studied, though the vortex core grew in size with angle of attack. These results are consistent with the finding that the net lift force acts between 45% and 46% span, measured from the root, in that any angle of attack variations in tip vortex strength or radius result in minimal changes in spanwise loading distribution.