Rotor inflow variability with advance ratio

A comparative study is conducted for the results of inflow calculations based on several analytical wake methods and laser-velocimeter rotor inflow measurements near a rectangular four-bladed rotor system operating in forward flight. The induced-flow characteristics at all advance ratios were found to be unsymmetrical about the longitudinal centerline, with maximum downwash in the rear portion of the disk, and skewed toward the advancing blade-side. Comparisons among analytical methods show that the region of induced upflow over the rotor disk was effectively modeled only at an advance ratio value of 0.15.