Experimental study of the three dimensionality of orthogonal blade vortex interaction

Abstract

Wind-tunnel tests were conducted to investigate orthogonalvortex interaction with a stationary blademimicking the main-rotor/tail-rotor interaction. High-quality experimental results with high-temporal resolution for the interaction have been obtained at different wind speeds and blade incidence angles. A vortex generator was specially designed for the experiment and produced stable trailing vortices. These were identified by hot-wire anemometry, with different vortical parameters for different speeds. When the measurement location is aligned with the vortex axis, pressure data reveal a suction peak on the upper blade surface and a pressure peak on the lower surface during the interaction. Significant dependence of the pressure on spanwise distance from the vortex indicates a strong three-dimensional interaction effect. For example, for spanwise positions above the core axis, a pressure pulse on the upper surface and a suction peak on the lower surface have been observed. It is shown that these differences can be attributed to the in fluence of the axial and tangential velocity components of the vortex. Pressure data for the blade at high incidence also show that the interaction can exacerbate and alleviate flow separation, depending on the spanwise position.