Investigation of Helicopter Rotor-Blade-Tip-Vortex Alleviation Using a Slotted Tip

Abstract

A slotted tip was developed to modify the characteristics of the strong vortex trailed from the tip of a small-scale helicopter blade. Forward-facing slots directed a slight amount of the incident flow in the spanwise direction, which was vented at the side edge of the blade tip. This caused the tip vortex to detach from the blade tip face, and also introduced turbulent vortlets into the laminar core of the developing vortex. The resulting wake flowfield was investigated using flow visualization and laser Doppler velocimetry. Measurements were conducted to quantify the vortex swirl velocity components, the inner core development, and the overall vortical flow inside the vortex trails. The results were then compared to a baseline blade with a standard unmodified rectangular tip