Experimental evaluation of a propulsive wing concept

Abstract

The work presented in this thesis was performed in support of a NASA LEARN project which aimed to develop a novel propulsive wing airfoil section which could be applied to a future-generation high-efficiency aircraft in order to further improve gains in efficiency over current aircraft. The designed airfoil section extended the Griffith/Goldschmied airfoil concept to a Mach number of 0.7 for extended runs of laminar flow, pressure thrust, and wake filling. A lowspeed wind tunnel test was performed using a model of the designed propulsive airfoil section in order to validate the tools which were used for design, as well as to verify the pressure thrust concept. Results from the airfoil test indicated that the suction-enabled airfoil was accurately modeled during the design phase. A large reduction of drag was also observed for the suction-enabled airfoil. Lift and drag compared well between computational predictions and experimental measurements for the airfoil test conditions. Experimental testing of a cross-flow fan was also performed in a transonic wind tunnel to characterize the fan power requirements and suction capabilities when embedded in a surface in transonic flow. Results from this test indicated that cross-flow fans are capable of aiding in pressure recovery, as well as producing a discrete pressure rise at the trailing-edge region of an airfoil. This pressure recovery and discrete pressure rise are are both necessary for the operation of the propulsive airfoil. Shaft power measurements were also taken during operation of the cross-flow fan, and results are presented to characterize the requirements of the fan over a variety of Mach number and RPM operating conditions. Finally, data from the cross-flow fan wind tunnel tests were scaled for use in a systems analysis which was also a part of the LEARN project

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