Date of Award
Doctor of Philosophy
Mechanical and Aeronautical Engineering
Dr. Parviz Merati
Dr. William Liou
Dr. Iskender Sahin
The purpose of this dissertation is to investigate the relationship between the flowfield surrounding an iced airfoil and the stall margin instrumentation developed for use in icing conditions. The stall margin system indicates to the pilot the change in available lift due to ice accretions on the leading edge of an airfoil. This system displays the change in the form of a normalized lift coefficient. Four pressure ports are chosen to specifically maintain a constant calibration curve, for pressure versus normalized lift coefficient, regardless of ice shape. This allows these pressures to be used to determine the change in maximum lift coefficient. The instrumentation currently maintains an accuracy of ±10%. There was a need to investigate the relationship between the flowfield and the port locations, and the airfoil shape and the port locations. This allowed further understanding of the placement of these ports. Through this investigation, better port locations have been determined and the accuracy and usefulness of the instrumentation has been increased.
This investigation was conducted using wind tunnel testing techniques. A 2-D NACA 23012 pressure model and a 2-D NACA 23012 force model were constructed and tested to determine initial port locations for the stall margin instrumentation. Simulated ice shapes were produced using the LEWICE software from NASA Glenn. The flowfield around the airfoil was mapped using smoke wire flow visualization and hotwire anemometry. A single wire system was used todetermine a 2-D profile of the turbulence intensity levels surrounding the ice covered wing. The movement of the separation region behind the ice shape, with change in angle of attack, was also investigated. The relationship between this movement and the port locations was documented and its significance determined. Through these observations, better port locations for the stall margin instrumentation were determined thus allowing accuracy of the instrumentation to be increased to +5%.
Pederson, Erik, "Investigation of the Iced Flowfield Characteristics Related to the Stall Margin Instrumentation Used in Icing Conditions" (2003). Dissertations. 1269.