Measurement of lift development on rapidly-accelerated wings
Abstract
Current analyses for treating the response of wings in unsteady flow fields are either extremely costly or involve major simplifications to allow calculation. Such simplifications normally include neglecting the effects of viscosity and assuming a simple wake model. The purpose of this investigation was to explore situations where such analyses were expected to fail, as well as work. For one set of tests, a large bore, short stroke air cylinder was used to give models a rapid acceleration to a constant speed. Other tests were performed using models under constant accelerations from rest. Lift as a function of time for various planforms was gathered using combinations of piezoelectric force transducers. The result of the Fast Start test was that the analytical indicial response function, derived for a finite wing, does manifest itself in a real test. Constant Acceleration tests furnished numerous conclusions. Response of a rectangular wing was much higher than expected, due to a finite development time for a laminar separation. Delta wing studies showed lower response than expected for pre-stall tests, possibly as a result of leading edge vortex burst movement under acceleration. Post-stall delta wing tests featured a nonmonotonic response with acceleration. This was attributed to a reformation or destruction of large scale structures in an otherwise "bluff body" wake.
Degree
Ph.D.
Advisors
Sullivan, Purdue University.
Subject Area
Aerospace materials
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