Unsteady Characteristics over Dynamic Delta Wings

Abstract

A study of flow and frequency characteristics of the leading-edge vortices over a delta wing undergoing pitching up-stop motions is presented. The experiments with the dynamic delta wings were conducted in a water channel and a wind tunnel respectively. Among them, the test of the flow visualization was completed in the water channel with the delta wing with pitching up-stop motions. The result shows that in the case of pitching up-stop movement the vortex breakdown position is dependent on the range of incidence at which the wing is subject to pitching up-stop and the reduced frequency k (k=c/2U∞). Analysis of the pressure signal measured in the wind tunnel shows when the delta wing is subject to pitching-up the nondimensional spiral wave frequency at nominal incidence in post-breakdown is higher than that at corresponding static state and the bigger the k is, the higher the nondimensional spiral wave frequency is. The same conclusion is fitted with different sweep delta wing.