Loading...
Faculty Mentor Name
Wallace Morris
Format Preference
Poster Presentation with Video
Abstract
As an airfoil’s AOA is increased, a small separation bubble forms on the upper surface, and grows until it bursts. This causes the laminar flow to massively separate from the upper surface. The bursting of the bubble coincides with the onset of stall. Stall hysteresis is the phenomenon where an airfoil produces less lift than expected for a given angle of attack as recovery from stall is attempted. Stall hysteresis is a well-documented phenomenon that has been shown to affect all aircraft and turbo-machinery (wind turbines, jet engines, etc.) This hysteresis poses a problem for aircraft control in the event of a stall, where the lift produced by the wing becomes dependent on the history of its AOA. The present work, as an extension of Morris 2009 and Morris and Rusak 2013, suggests that the flow state around a 2D airfoil is dominated by the circulation parameter, which includes airfoil geometry, angle of attack, and Reynolds number effects. It is proposed that stalled airfoils have a significantly different circulation parameter than that of the attached states for the same airfoil. This variance in circulation parameter has associated stall-circulation parameters for each state (attached vs stalled), and it, therefore, necessary to reduce the angle of attack, or the circulation parameter, below that of the effective body (stalled flow field). The flow field is dominated not by the physical airfoil, but rather by the effective body encompassing both the physical airfoil and its trailing wake.
- POSTER PRESENTATION
Continual Analysis of the Relationship Between Stall Hysteresis and Circulation Parameter
As an airfoil’s AOA is increased, a small separation bubble forms on the upper surface, and grows until it bursts. This causes the laminar flow to massively separate from the upper surface. The bursting of the bubble coincides with the onset of stall. Stall hysteresis is the phenomenon where an airfoil produces less lift than expected for a given angle of attack as recovery from stall is attempted. Stall hysteresis is a well-documented phenomenon that has been shown to affect all aircraft and turbo-machinery (wind turbines, jet engines, etc.) This hysteresis poses a problem for aircraft control in the event of a stall, where the lift produced by the wing becomes dependent on the history of its AOA. The present work, as an extension of Morris 2009 and Morris and Rusak 2013, suggests that the flow state around a 2D airfoil is dominated by the circulation parameter, which includes airfoil geometry, angle of attack, and Reynolds number effects. It is proposed that stalled airfoils have a significantly different circulation parameter than that of the attached states for the same airfoil. This variance in circulation parameter has associated stall-circulation parameters for each state (attached vs stalled), and it, therefore, necessary to reduce the angle of attack, or the circulation parameter, below that of the effective body (stalled flow field). The flow field is dominated not by the physical airfoil, but rather by the effective body encompassing both the physical airfoil and its trailing wake.
- POSTER PRESENTATION