Flat-Plate Wings Interacting with Finite Channels: Changes with Approach Distance

The effect of a flat-plate wing at high-incidence translating towards a rectangular channel with varying approach distances is examined in a water towing tank. A reference case shows the lift behavior decays and vortex shedding becomes quasi-periodic after about 20 chords traveled. Cases studied include varying the approach length such that the wing enters the channel during different phases of the leading-edge vortex (LEV) cycle. These cases include near LEV pinch-off, LEV shedding, and LEV formation. The channel lengths and gap-heights (blockage ratio) are also varied, and the wing travels at Reynolds number 6,000. Channel blockage produces a lift deviation from the reference case before the wing reaches the channel, considered a "warning." Consistent with previous results, the blockage causes faster vortex shedding and higher lift. When an LEV forms fully in a channel, this produces the highest in-channel lift peak; entering with LEV formation in progress yields the lowest relative peak, still above the reference. For reduced blockage, the wing experiences a series of increasing lift peaks in the channel, while the opposite occurs for higher blockage. Additional flow information provides insight into the effects of vortex interaction on lift behavior.